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  • rsyslogd not monitoring all files

    - by Tom O'Connor
    So.. I've installed Logstash, and instead of using the logstash shipper (because it needs the JVM and is generally massive), I'm using rsyslogd with the following configuration. # Use traditional timestamp format $ActionFileDefaultTemplate RSYSLOG_TraditionalFileFormat $IncludeConfig /etc/rsyslog.d/*.conf # Provides kernel logging support (previously done by rklogd) $ModLoad imklog # Provides support for local system logging (e.g. via logger command) $ModLoad imuxsock # Log all kernel messages to the console. # Logging much else clutters up the screen. #kern.* /dev/console # Log anything (except mail) of level info or higher. # Don't log private authentication messages! *.info;mail.none;authpriv.none;cron.none;local6.none /var/log/messages # The authpriv file has restricted access. authpriv.* /var/log/secure # Log all the mail messages in one place. mail.* -/var/log/maillog # Log cron stuff cron.* /var/log/cron # Everybody gets emergency messages *.emerg * # Save news errors of level crit and higher in a special file. uucp,news.crit /var/log/spooler # Save boot messages also to boot.log local7.* /var/log/boot.log In /etc/rsyslog.d/logstash.conf there are 28 file monitor blocks using imfile $ModLoad imfile # Load the imfile input module $ModLoad imklog # for reading kernel log messages $ModLoad imuxsock # for reading local syslog messages $InputFileName /var/log/rabbitmq/startup_err $InputFileTag rmq-err: $InputFileStateFile state-rmq-err $InputFileFacility local6 $InputRunFileMonitor .... $InputFileName /var/log/some.other.custom.log $InputFileTag cust-log: $InputFileStateFile state-cust-log $InputFileFacility local6 $InputRunFileMonitor .... *.* @@10.90.0.110:5514 There are 28 InputFileMonitor blocks, each monitoring a different custom application logfile.. If I run [root@secret-gm02 ~]# lsof|grep rsyslog rsyslogd 5380 root cwd DIR 253,0 4096 2 / rsyslogd 5380 root rtd DIR 253,0 4096 2 / rsyslogd 5380 root txt REG 253,0 278976 1015955 /sbin/rsyslogd rsyslogd 5380 root mem REG 253,0 58400 1868123 /lib64/libgcc_s-4.1.2-20080825.so.1 rsyslogd 5380 root mem REG 253,0 144776 1867778 /lib64/ld-2.5.so rsyslogd 5380 root mem REG 253,0 1718232 1867780 /lib64/libc-2.5.so rsyslogd 5380 root mem REG 253,0 23360 1867787 /lib64/libdl-2.5.so rsyslogd 5380 root mem REG 253,0 145872 1867797 /lib64/libpthread-2.5.so rsyslogd 5380 root mem REG 253,0 85544 1867815 /lib64/libz.so.1.2.3 rsyslogd 5380 root mem REG 253,0 53448 1867801 /lib64/librt-2.5.so rsyslogd 5380 root mem REG 253,0 92816 1868016 /lib64/libresolv-2.5.so rsyslogd 5380 root mem REG 253,0 20384 1867990 /lib64/rsyslog/lmnsd_ptcp.so rsyslogd 5380 root mem REG 253,0 53880 1867802 /lib64/libnss_files-2.5.so rsyslogd 5380 root mem REG 253,0 23736 1867800 /lib64/libnss_dns-2.5.so rsyslogd 5380 root mem REG 253,0 20768 1867988 /lib64/rsyslog/lmnet.so rsyslogd 5380 root mem REG 253,0 11488 1867982 /lib64/rsyslog/imfile.so rsyslogd 5380 root mem REG 253,0 24040 1867983 /lib64/rsyslog/imklog.so rsyslogd 5380 root mem REG 253,0 11536 1867987 /lib64/rsyslog/imuxsock.so rsyslogd 5380 root mem REG 253,0 13152 1867989 /lib64/rsyslog/lmnetstrms.so rsyslogd 5380 root mem REG 253,0 8400 1867992 /lib64/rsyslog/lmtcpclt.so rsyslogd 5380 root 0r REG 0,3 0 4026531848 /proc/kmsg rsyslogd 5380 root 1u IPv4 1200589517 0t0 TCP 10.10.10.90 t:40629->10.10.10.90:5514 (ESTABLISHED) rsyslogd 5380 root 2u IPv4 1200589527 0t0 UDP *:45801 rsyslogd 5380 root 3w REG 253,3 17999744 2621483 /var/log/messages rsyslogd 5380 root 4w REG 253,3 13383 2621484 /var/log/secure rsyslogd 5380 root 5w REG 253,3 7180 2621493 /var/log/maillog rsyslogd 5380 root 6w REG 253,3 43321 2621529 /var/log/cron rsyslogd 5380 root 7w REG 253,3 0 2621494 /var/log/spooler rsyslogd 5380 root 8w REG 253,3 0 2621495 /var/log/boot.log rsyslogd 5380 root 9r REG 253,3 1064271998 2621464 /var/log/custom-application.monolog.log rsyslogd 5380 root 10u unix 0xffff81081fad2e40 0t0 1200589511 /dev/log You can see that there are nowhere near 28 logfiles actually being read. I really had to get one file monitored, so I moved it to the top, and it picked it up, but I'd like to be able to monitor all 28+ files, and not have to worry. OS is Centos 5.5 Kernel 2.6.18-308.el5 rsyslogd 3.22.1, compiled with: FEATURE_REGEXP: Yes FEATURE_LARGEFILE: Yes FEATURE_NETZIP (message compression): Yes GSSAPI Kerberos 5 support: Yes FEATURE_DEBUG (debug build, slow code): No Atomic operations supported: Yes Runtime Instrumentation (slow code): No Questions: Why is rsyslogd only monitoring a very small subset of the files? How can I fix this so that all the files are monitored?

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  • An error occured synchronizing windows with time.windows.com

    - by Killrawr
    Okay so I've tried stopping/registering the win32tm service on this Windows Server 2008 Enterprise Computer. C:\Users\Administrator>net stop w32time The Windows Time service is stopping. The Windows Time service was stopped successfully. C:\Users\Administrator>w32tm /unregister The following error occurred: Access is denied. (0x80070005) C:\Users\Administrator>w32tm /unregister W32Time successfully unregistered. C:\Users\Administrator>w32tm /register W32Time successfully registered. C:\Users\Administrator>net start w32time The Windows Time service is starting. The Windows Time service was started successfully. (Source : http://social.technet.microsoft.com/Forums/en-US/winserverDS/thread/9bdfc2cc-4775-4435-8868-57d214e1e3ba/) And I get this error from the Date and Time, Internet Time tab (After also following the steps here). I've even tried the Atomic Time Clock Worldtimeserver and I get the error The following error occurred: The specified module could not be found. (0x8007007E). I've also disabled the Windows Firewall, that might of been blocking the synchronization. I've done a file scan with sfc /scannow that came back with no errors. C:\Users\Administrator>sfc /scannow Beginning system scan. This process will take some time. Beginning verification phase of system scan. Verification 100% complete. Windows Resource Protection did not find any integrity violations. C:\Users\Administrator> But I'm not having much luck. Is there anyway lo possibly solve this? or is the time.windows.com servers unsupported? because the software is from 2008? (I really don't know :/), My ping result to time.windows.com C:\Users\Administrator>ping time.windows.com Pinging time.microsoft.akadns.net [65.55.21.22] with 32 bytes of data: Request timed out. Request timed out. Request timed out. Request timed out. Ping statistics for 65.55.21.22: Packets: Sent = 4, Received = 0, Lost = 4 (100% loss), And tracert result C:\Users\Administratortracert time.windows.com Tracing route to time.microsoft.akadns.net [65.55.21.24] over a maximum of 30 hops: 1 1 ms <1 ms <1 ms 192.168.1.1 2 32 ms 31 ms 32 ms be2-100.bras1wtc.wlg.vf.net.nz [203.109.129.113] 3 31 ms 32 ms 31 ms be5-100.ppnzwtc01.wlg.vf.net.nz.129.109.203.in-a ddr.arpa [203.109.129.114] 4 31 ms 31 ms 31 ms gi0-2-0-3.ppnzwtc01.wlg.vf.net.nz.180.109.203.in -addr.arpa [203.109.180.210] 5 31 ms 31 ms 30 ms gi0-2-0-3.ppnzwtc02.wlg.vf.net.nz [203.109.180.2 09] 6 167 ms 166 ms 166 ms ip-141.199.31.114.VOCUS.net.au [114.31.199.141] 7 175 ms 175 ms 175 ms microsoft.com.any2ix.coresite.com [206.223.143.1 43] 8 177 ms 180 ms 176 ms xe-7-0-2-0.by2-96c-1a.ntwk.msn.net [207.46.42.17 6] 9 205 ms 205 ms 204 ms xe-10-0-2-0.co1-96c-1b.ntwk.msn.net [207.46.45.3 1] 10 * * * Request timed out. 11 * * * Request timed out. 12 * * * Request timed out. 13 * * * Request timed out. 14 * * * Request timed out. 15 * * * Request timed out. 16 ^C And nslookup C:\Users\Administrator>nslookup time.windows.com Server: UnKnown Address: 192.168.1.1 Non-authoritative answer: Name: time.microsoft.akadns.net Address: 65.55.21.22 Aliases: time.windows.com

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  • Amazon EC2 Instance - m1.medium Ubuntu 12.04 - Started to crash three days ago

    - by Joy
    The environment: Amazon EC2 Instance - m1.medium Ubuntu 12.04 Apache 2.2.22 - Running a Drupal Site Using MySQL DB Server RAM info: ~$ free -gt total used free shared buffers cached Mem: 3 1 2 0 0 0 -/+ buffers/cache: 0 2 Swap: 0 0 0 Total: 3 1 2 Hard drive info: Filesystem Size Used Avail Use% Mounted on /dev/xvda1 7.9G 4.7G 2.9G 62% / udev 1.9G 8.0K 1.9G 1% /dev tmpfs 751M 180K 750M 1% /run none 5.0M 0 5.0M 0% /run/lock none 1.9G 0 1.9G 0% /run/shm /dev/xvdb 394G 199M 374G 1% /mnt The problem About two days ago the site started failing becaue the MySQL server was shut down by Apache with the following message: kernel: [2963685.664359] [31716] 106 31716 226946 22748 0 0 0 mysqld kernel: [2963685.664730] Out of memory: Kill process 31716 (mysqld) score 23 or sacrifice child kernel: [2963685.664764] Killed process 31716 (mysqld) total-vm:907784kB, anon-rss:90992kB, file-rss:0kB kernel: [2963686.153608] init: mysql main process (31716) killed by KILL signal kernel: [2963686.169294] init: mysql main process ended, respawning That states that the VM was occupying 0.9GB, but my Ram has 2GB free, so 1GB was still left free. I understand that in Linux applications can allocate more memory than physically available. I don't know if this is the problme, it's the first time that it has started to happen. Obviously, the MySQL server tries to restart, but there's no memory for it apparently and it won't restart. Here is its error log: Plugin 'FEDERATED' is disabled. The InnoDB memory heap is disabled Mutexes and rw_locks use GCC atomic builtins Compressed tables use zlib 1.2.3.4 Initializing buffer pool, size = 128.0M InnoDB: mmap(137363456 bytes) failed; errno 12 Completed initialization of buffer pool Fatal error: cannot allocate memory for the buffer pool Plugin 'InnoDB' init function returned error. Plugin 'InnoDB' registration as a STORAGE ENGINE failed. Unknown/unsupported storage engine: InnoDB [ERROR] Aborting [Note] /usr/sbin/mysqld: Shutdown complete I simply restarted the Mysql service. About two hours later it happened again. I restarted it. Then it happened again 9 hours later. So then I thought of the MaxClients parameter of apache.conf, so I went to check it out. It was set at 150. I decided to drop it down to 60. As so: <IfModule mpm_prefork_module> ... MaxClients 60 </IfModule> <IfModule mpm_worker_module> ... MaxClients 60 </IfModule> <IfModule mpm_event_module> ... MaxClients 60 </IfModule> Once I did that, I had the apache2 service restart and it all went smoothly for 3/4 of a day. Since at night the MySQL service shut down once again, but this time it wasn't killed by the Apache2 service. Instead it called the OOM-Killer with the following message: kernel: [3104680.005312] mysqld invoked oom-killer: gfp_mask=0x201da, order=0, oom_adj=0, oom_score_adj=0 kernel: [3104680.005351] [<ffffffff81119795>] oom_kill_process+0x85/0xb0 kernel: [3104680.548860] init: mysql main process (30821) killed by KILL signal Now I'm out of ideas. Some articles state that the ideal thing to do is change the kernel behaviour with the following (include it to the file /etc/sysctl.conf ) vm.overcommit_memory = 2 vm.overcommit_ratio = 80 So no overcommits will take place. I'm wondering if this is the way to go? Keep in mind I'm no server administrator, I have basic knowldege. Thanks a bunch in advance.

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  • MySQL InnoDB disappeared, all InnoDB data cant be accessed

    - by dogmatic69
    Mysql (including InnoDB) was working fine, after a restart the other day when mysql starts it says in the logs: 140604 23:36:07 [Note] Plugin 'FEDERATED' is disabled. 140604 23:36:07 [Note] Plugin 'InnoDB' is disabled. In the app it says: SQLSTATE[42000]: Syntax error or access violation: 1286 Unknown storage engine 'InnoDB' Now, according to google this is a very simple fix, just remove the ib_logfile[0|1] files, which I have done and does not do anything. I started by making a full copy of the data dir for testing various 'fixes'. I have also uninstalled mysql and reinstalled it with no change, I just cant get it to run with innodb working anymore :/ # mysql --version mysql Ver 14.14 Distrib 5.5.37, for debian-linux-gnu (x86_64) using readline 6.3 I have also tried the innodb_force_recovery setting, 0 - 6, Any time I run a command on an InnoDB table it says innodb_force_recovery LOGS (from around the time it died) was working here Version: '5.5.37-0ubuntu0.14.04.1' socket: '/var/run/mysqld/mysqld.sock' port: 3306 (Ubuntu) 140530 1:24:22 [Note] /usr/sbin/mysqld: Normal shutdown 140530 1:24:22 [Note] Event Scheduler: Purging the queue. 0 events 140530 1:24:22 InnoDB: Starting shutdown... 140530 1:24:24 InnoDB: Shutdown completed; log sequence number 3345857316 140530 1:24:24 [Note] /usr/sbin/mysqld: Shutdown complete 140530 22:03:12 [Warning] Using unique option prefix myisam-recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead. 140530 22:03:12 [Note] Plugin 'FEDERATED' is disabled. 140530 22:03:12 InnoDB: The InnoDB memory heap is disabled 140530 22:03:12 InnoDB: Mutexes and rw_locks use GCC atomic builtins 140530 22:03:12 InnoDB: Compressed tables use zlib 1.2.8 140530 22:03:12 InnoDB: Using Linux native AIO 140530 22:03:12 InnoDB: Initializing buffer pool, size = 128.0M 140530 22:03:12 InnoDB: Completed initialization of buffer pool 140530 22:03:12 InnoDB: highest supported file format is Barracuda. 140530 22:03:15 InnoDB: Waiting for the background threads to start 140530 22:03:16 InnoDB: 5.5.37 started; log sequence number 3345857316 140530 22:03:16 [Note] Server hostname (bind-address): '192.168.1.20'; port: 3306 140530 22:03:16 [Note] - '192.168.1.20' resolves to '192.168.1.20'; 140530 22:03:16 [Note] Server socket created on IP: '192.168.1.20'. 140530 22:03:16 [Note] Event Scheduler: Loaded 0 events 140530 22:03:16 [Note] /usr/sbin/mysqld: ready for connections. 140602 0:58:39 [Note] Event Scheduler: Purging the queue. 0 events 140602 0:58:39 InnoDB: Starting shutdown... 140602 0:58:41 InnoDB: Shutdown completed; log sequence number 3345954467 140602 0:58:41 [Note] /usr/sbin/mysqld: Shutdown complete does not work anymore 140602 21:45:19 [Warning] Using unique option prefix myisam-recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead. 140602 21:45:19 [Note] Plugin 'FEDERATED' is disabled. 140602 21:45:19 [Note] Plugin 'InnoDB' is disabled. 140602 21:45:19 [Note] Server hostname (bind-address): '192.168.1.20'; port: 3306 140602 21:45:19 [Note] - '192.168.1.20' resolves to '192.168.1.20'; 140602 21:45:19 [Note] Server socket created on IP: '192.168.1.20'. 140602 21:45:19 [Note] Event Scheduler: Loaded 0 events 140602 21:45:19 [Note] /usr/sbin/mysqld: ready for connections.

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  • MySQL crash. Unknown cause. Signal 11

    - by fortmac
    This is a database that I installed ~6 months ago and had been running fine. This is currently running in Ubuntu 12.04. Attempting to connect to MySQL causes this error: ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (111) Then theres: $ sudo mysqld which returns: 130702 15:38:54 [Note] Plugin 'FEDERATED' is disabled. 130702 15:38:54 InnoDB: The InnoDB memory heap is disabled 130702 15:38:54 InnoDB: Mutexes and rw_locks use GCC atomic builtins 130702 15:38:54 InnoDB: Compressed tables use zlib 1.2.3.4 130702 15:38:54 InnoDB: Initializing buffer pool, size = 128.0M 130702 15:38:54 InnoDB: Completed initialization of buffer pool 130702 15:38:54 InnoDB: highest supported file format is Barracuda. InnoDB: The log sequence number in ibdata files does not match InnoDB: the log sequence number in the ib_logfiles! 130702 15:38:54 InnoDB: Database was not shut down normally! InnoDB: Starting crash recovery. InnoDB: Reading tablespace information from the .ibd files... InnoDB: Restoring possible half-written data pages from the doublewrite InnoDB: buffer... 130702 15:38:55 InnoDB: Waiting for the background threads to start 130702 15:38:56 InnoDB: 1.1.8 started; log sequence number 5201901917 130702 15:38:56 [Note] Server hostname (bind-address): '127.0.0.1'; port: 3306 130702 15:38:56 [Note] - '127.0.0.1' resolves to '127.0.0.1'; 130702 15:38:56 [Note] Server socket created on IP: '127.0.0.1'. 130702 15:38:56 [Note] Event Scheduler: Loaded 0 events 130702 15:38:56 [Note] mysqld: ready for connections. Version: '5.5.28-0ubuntu0.12.04.3' socket: '/var/run/mysqld/mysqld.sock' port: 3306 (Ubuntu) 19:39:02 UTC - mysqld got signal 11 ; This could be because you hit a bug. It is also possible that this binary or one of the libraries it was linked against is corrupt, improperly built, or misconfigured. This error can also be caused by malfunctioning hardware. We will try our best to scrape up some info that will hopefully help diagnose the problem, but since we have already crashed, something is definitely wrong and this may fail. key_buffer_size=16777216 read_buffer_size=131072 max_used_connections=1 max_threads=151 thread_count=1 connection_count=1 It is possible that mysqld could use up to key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 346681 K bytes of memory Hope that's ok; if not, decrease some variables in the equation. Thread pointer: 0x7f9509e51530 Attempting backtrace. You can use the following information to find out where mysqld died. If you see no messages after this, something went terribly wrong... stack_bottom = 7f94f1d3de60 thread_stack 0x30000 mysqld(my_print_stacktrace+0x29)[0x7f95083427b9] mysqld(handle_fatal_signal+0x483)[0x7f9508209b43] /lib/x86_64-linux-gnu/libpthread.so.0(+0xfcb0)[0x7f9506f5bcb0] mysqld(+0x320e1c)[0x7f9508113e1c] mysqld(_ZN4JOIN15alloc_func_listEv+0x9c)[0x7f950812391c] mysqld(_ZN4JOIN7prepareEPPP4ItemP10TABLE_LISTjS1_jP8st_orderS7_S1_S7_P13st_select_lexP18st_select_lex_unit+0x918)[0x7f9508124658] mysqld(_Z12mysql_selectP3THDPPP4ItemP10TABLE_LISTjR4ListIS1_ES2_jP8st_orderSB_S2_SB_yP13select_resultP18st_select_lex_unitP13st_select_lex+0x130)[0x7f950812d060] mysqld(_Z13handle_selectP3THDP3LEXP13select_resultm+0x17c)[0x7f9508132fbc] mysqld(+0x2f6714)[0x7f95080e9714] mysqld(_Z21mysql_execute_commandP3THD+0x16d8)[0x7f95080f1178] mysqld(_Z11mysql_parseP3THDPcjP12Parser_state+0x10f)[0x7f95080f5e0f] mysqld(_Z16dispatch_command19enum_server_commandP3THDPcj+0x1380)[0x7f95080f7260] mysqld(_Z24do_handle_one_connectionP3THD+0x1bd)[0x7f950819b80d] mysqld(handle_one_connection+0x50)[0x7f950819b870] /lib/x86_64-linux-gnu/libpthread.so.0(+0x7e9a)[0x7f9506f53e9a] /lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f9506684cbd] Trying to get some variables. Some pointers may be invalid and cause the dump to abort. Query (7f94e0004b80): is an invalid pointer Connection ID (thread ID): 1 Status: NOT_KILLED The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains information that should help you find out what is causing the crash. I'm at a loss. What other reports would be useful in diagnosing this? /var/log/mysql.err & /var/log/mysql.log are empty.

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  • T4 Performance Counters explained

    - by user13346607
    Now that T4 is out for a few month some people might have wondered what details of the new pipeline you can monitor. A "cpustat -h" lists a lot of events that can be monitored, and only very few are self-explanatory. I will try to give some insight on all of them, some of these "PIC events" require an in-depth knowledge of T4 pipeline. Over time I will try to explain these, for the time being these events should simply be ignored. (Side note: some counters changed from tape-out 1.1 (*only* used in the T4 beta program) to tape-out 1.2 (used in the systems shipping today) The table only lists the tape-out 1.2 counters) 0 0 1 1058 6033 Oracle Microelectronics 50 14 7077 14.0 Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:Cambria; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} pic name (cpustat) Prose Comment Sel-pipe-drain-cycles, Sel-0-[wait|ready], Sel-[1,2] Sel-0-wait counts cycles a strand waits to be selected. Some reasons can be counted in detail; these are: Sel-0-ready: Cycles a strand was ready but not selected, that can signal pipeline oversubscription Sel-1: Cycles only one instruction or µop was selected Sel-2: Cycles two instructions or µops were selected Sel-pipe-drain-cycles: cf. PRM footnote 8 to table 10.2 Pick-any, Pick-[0|1|2|3] Cycles one, two, three, no or at least one instruction or µop is picked Instr_FGU_crypto Number of FGU or crypto instructions executed on that vcpu Instr_ld dto. for load Instr_st dto. for store SPR_ring_ops dto. for SPR ring ops Instr_other dto. for all other instructions not listed above, PRM footnote 7 to table 10.2 lists the instructions Instr_all total number of instructions executed on that vcpu Sw_count_intr Nr of S/W count instructions on that vcpu (sethi %hi(fc000),%g0 (whatever that is))  Atomics nr of atomic ops, which are LDSTUB/a, CASA/XA, and SWAP/A SW_prefetch Nr of PREFETCH or PREFETCHA instructions Block_ld_st Block loads or store on that vcpu IC_miss_nospec, IC_miss_[L2_or_L3|local|remote]\ _hit_nospec Various I$ misses, distinguished by where they hit. All of these count per thread, but only primary events: T4 counts only the first occurence of an I$ miss on a core for a certain instruction. If one strand misses in I$ this miss is counted, but if a second strand on the same core misses while the first miss is being resolved, that second miss is not counted This flavour of I$ misses counts only misses that are caused by instruction that really commit (note the "_nospec") BTC_miss Branch target cache miss ITLB_miss ITLB misses (synchronously counted) ITLB_miss_asynch dto. but asynchronously [I|D]TLB_fill_\ [8KB|64KB|4MB|256MB|2GB|trap] H/W tablewalk events that fill ITLB or DTLB with translation for the corresponding page size. The “_trap” event occurs if the HWTW was not able to fill the corresponding TLB IC_mtag_miss, IC_mtag_miss_\ [ptag_hit|ptag_miss|\ ptag_hit_way_mismatch] I$ micro tag misses, with some options for drill down Fetch-0, Fetch-0-all fetch-0 counts nr of cycles nothing was fetched for this particular strand, fetch-0-all counts cycles nothing was fetched for all strands on a core Instr_buffer_full Cycles the instruction buffer for a strand was full, thereby preventing any fetch BTC_targ_incorrect Counts all occurences of wrongly predicted branch targets from the BTC [PQ|ROB|LB|ROB_LB|SB|\ ROB_SB|LB_SB|RB_LB_SB|\ DTLB_miss]\ _tag_wait ST_q_tag_wait is listed under sl=20. These counters monitor pipeline behaviour therefore they are not strand specific: PQ_...: cycles Rename stage waits for a Pick Queue tag (might signal memory bound workload for single thread mode, cf. Mail from Richard Smith) ROB_...: cycles Select stage waits for a ROB (ReOrderBuffer) tag LB_...: cycles Select stage waits for a Load Buffer tag SB_...: cycles Select stage waits for Store Buffer tag combinations of the above are allowed, although some of these events can overlap, the counter will only be incremented once per cycle if any of these occur DTLB_...: cycles load or store instructions wait at Pick stage for a DTLB miss tag [ID]TLB_HWTW_\ [L2_hit|L3_hit|L3_miss|all] Counters for HWTW accesses caused by either DTLB or ITLB misses. Canbe further detailed by where they hit IC_miss_L2_L3_hit, IC_miss_local_remote_remL3_hit, IC_miss I$ prefetches that were dropped because they either miss in L2$ or L3$ This variant counts misses regardless if the causing instruction commits or not DC_miss_nospec, DC_miss_[L2_L3|local|remote_L3]\ _hit_nospec D$ misses either in general or detailed by where they hit cf. the explanation for the IC_miss in two flavours for an explanation of _nospec and the reasoning for two DC_miss counters DTLB_miss_asynch counts all DTLB misses asynchronously, there is no way to count them synchronously DC_pref_drop_DC_hit, SW_pref_drop_[DC_hit|buffer_full] L1-D$ h/w prefetches that were dropped because of a D$ hit, counted per core. The others count software prefetches per strand [Full|Partial]_RAW_hit_st_[buf|q] Count events where a load wants to get data that has not yet been stored, i. e. it is still inside the pipeline. The data might be either still in the store buffer or in the store queue. If the load's data matches in the SB and in the store queue the data in buffer takes precedence of course since it is younger [IC|DC]_evict_invalid, [IC|DC|L1]_snoop_invalid, [IC|DC|L1]_invalid_all Counter for invalidated cache evictions per core St_q_tag_wait Number of cycles pipeline waits for a store queue tag, of course counted per core Data_pref_[drop_L2|drop_L3|\ hit_L2|hit_L3|\ hit_local|hit_remote] Data prefetches that can be further detailed by either why they were dropped or where they did hit St_hit_[L2|L3], St_L2_[local|remote]_C2C, St_local, St_remote Store events distinguished by where they hit or where they cause a L2 cache-to-cache transfer, i.e. either a transfer from another L2$ on the same die or from a different die DC_miss, DC_miss_\ [L2_L3|local|remote]_hit D$ misses either in general or detailed by where they hit cf. the explanation for the IC_miss in two flavours for an explanation of _nospec and the reasoning for two DC_miss counters L2_[clean|dirty]_evict Per core clean or dirty L2$ evictions L2_fill_buf_full, L2_wb_buf_full, L2_miss_buf_full Per core L2$ buffer events, all count number of cycles that this state was present L2_pipe_stall Per core cycles pipeline stalled because of L2$ Branches Count branches (Tcc, DONE, RETRY, and SIT are not counted as branches) Br_taken Counts taken branches (Tcc, DONE, RETRY, and SIT are not counted as branches) Br_mispred, Br_dir_mispred, Br_trg_mispred, Br_trg_mispred_\ [far_tbl|indir_tbl|ret_stk] Counter for various branch misprediction events.  Cycles_user counts cycles, attribute setting hpriv, nouser, sys controls addess space to count in Commit-[0|1|2], Commit-0-all, Commit-1-or-2 Number of times either no, one, or two µops commit for a strand. Commit-0-all counts number of times no µop commits for the whole core, cf. footnote 11 to table 10.2 in PRM for a more detailed explanation on how this counters interacts with the privilege levels

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  • Task scheduler ran a task twice

    - by Ross Buggins
    Update: This has now happened two days in a row. Update: XML of scheduled tasks and images now included. Two servers located in London, both Windows 2012, have a scheduled task set to run at 3pm Monday to Friday. This has been set up for the last 5 months without a problem. However, on Monday the 28th of August they both ran the scheduled task at 3pm and then again at 4pm. When it was first reported, I thought it was too much of a coincidence to be the day after the clocks had gone back an hour. However, I’m failing in being able to explain why it has happened and if it is related to the clock change at all. The relevant logs from one server (the logs for the other follow this pattern as well): Event 129 15:00:20 Task Scheduler launch task "\3pm", instance "C:\Program Files (x86)\PHP\v5.4\php.exe" with process ID 2388. Event 100 15:00:20 Task Scheduler started "{75a3590f-dec1-4dee-bd27-73d63a50a9d7}" instance of the "\3pm" task for user "x\y". Event 200 15:00:20 Task Scheduler launched action "C:\Program Files (x86)\PHP\v5.4\php.exe" in instance "{75a3590f-dec1-4dee-bd27-73d63a50a9d7}" of task "\3pm". Event 201 15:00:23 Task Scheduler successfully completed task "\3pm" , instance "{75a3590f-dec1-4dee-bd27-73d63a50a9d7}" , action "C:\Program Files (x86)\PHP\v5.4\php.exe" with return code 0. Event 129 16:00:20 Task Scheduler launch task "\3pm", instance "C:\Program Files (x86)\PHP\v5.4\php.exe" with process ID 1224. Event 100 16:00:20 Task Scheduler started "{3dd46ca9-c525-4796-86b5-5e513fd45f26}" instance of the "\3pm" task for user "x\y". Event 200 16:00:20 Task Scheduler launched action "C:\Program Files (x86)\PHP\v5.4\php.exe" in instance "{3dd46ca9-c525-4796-86b5-5e513fd45f26}" of task "\3pm". Event 201 16:00:23 Task Scheduler successfully completed task "\3pm" , instance "{3dd46ca9-c525-4796-86b5-5e513fd45f26}" , action "C:\Program Files (x86)\PHP\v5.4\php.exe" with return code 0. I've seen this question Scheduled task running twice from time to time which points to a bug at http://support.microsoft.com/kb/2461249 being the cause. However, this doesn't include Server 2012 in it's list of problem operating systems. I’m struggling to explain this, can anyone else? The XML export for the scheduled task is: <?xml version="1.0" encoding="UTF-16"?> <Task version="1.2" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task"> <RegistrationInfo> <Date>2013-04-16T14:04:17.4897806</Date> <Author>x\y</Author> </RegistrationInfo> <Triggers> <CalendarTrigger> <StartBoundary>2013-04-17T15:00:20</StartBoundary> <Enabled>true</Enabled> <ScheduleByWeek> <DaysOfWeek> <Monday /> <Tuesday /> <Wednesday /> <Thursday /> <Friday /> </DaysOfWeek> <WeeksInterval>1</WeeksInterval> </ScheduleByWeek> </CalendarTrigger> </Triggers> <Principals> <Principal id="Author"> <UserId>x\y</UserId> <LogonType>Password</LogonType> <RunLevel>LeastPrivilege</RunLevel> </Principal> </Principals> <Settings> <MultipleInstancesPolicy>IgnoreNew</MultipleInstancesPolicy> <DisallowStartIfOnBatteries>true</DisallowStartIfOnBatteries> <StopIfGoingOnBatteries>true</StopIfGoingOnBatteries> <AllowHardTerminate>true</AllowHardTerminate> <StartWhenAvailable>false</StartWhenAvailable> <RunOnlyIfNetworkAvailable>false</RunOnlyIfNetworkAvailable> <IdleSettings> <StopOnIdleEnd>true</StopOnIdleEnd> <RestartOnIdle>false</RestartOnIdle> </IdleSettings> <AllowStartOnDemand>true</AllowStartOnDemand> <Enabled>true</Enabled> <Hidden>false</Hidden> <RunOnlyIfIdle>false</RunOnlyIfIdle> <WakeToRun>false</WakeToRun> <ExecutionTimeLimit>P3D</ExecutionTimeLimit> <Priority>7</Priority> </Settings> <Actions Context="Author"> <Exec> <Command>"C:\Program Files (x86)\PHP\v5.4\php.exe"</Command> <Arguments>-f "c:\a.php"</Arguments> </Exec> </Actions> </Task> 29 October 17:00 - Update - Both servers have again run the scheduled task at 15:00 and 16:00. I've now updated the php file that is run by the scheduler to not actually do anything whilst I'm going through trying to solve this. I'm planning on restarting one server to see if this changes anything tomorrow. 30 October 08:25 - Update - When exporting the task XML I remembered that I hadn't included the fact that the scheduled task on second server was created by importing the XML of the task created on the first. The only difference between the two tasks is the path of the php file they are executing and the user account that they are running as.

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  • Another Marketing Conference, part one – the best morning sessions.

    - by Roger Hart
    Yesterday I went to Another Marketing Conference. I honestly can’t tell if the title is just tipping over into smug, but in the balance of things that doesn’t matter, because it was a good conference. There was an enjoyable blend of theoretical and practical, and enough inter-disciplinary spread to keep my inner dilettante grinning from ear to ear. Sure, there was a bumpy bit in the middle, with two back-to-back sales pitches and a rather thin overview of the state of the web. But the signal:noise ratio at AMC2012 was impressively high. Here’s the first part of my write-up of the sessions. It’s a bit of a mammoth. It’s also a bit of a mash-up of what was said and what I thought about it. I’ll add links to the videos and slides from the sessions as they become available. Although it was in the morning session, I’ve not included Vanessa Northam’s session on the power of internal comms to build brand ambassadors. It’ll be in the next roundup, as this is already pushing 2.5k words. First, the important stuff. I was keeping a tally, and nobody said “synergy” or “leverage”. I did, however, hear the term “marketeers” six times. Shame on you – you know who you are. 1 – Branding in a post-digital world, Graham Hales This initially looked like being a sales presentation for Interbrand, but Graham pulled it out of the bag a few minutes in. He introduced a model for brand management that was essentially Plan >> Do >> Check >> Act, with Do and Check rolled up together, and went on to stress that this looks like on overall business management model for a reason. Brand has to be part of your overall business strategy and metrics if you’re going to care about it at all. This was the first iteration of what proved to be one of the event’s emergent themes: do it throughout the stack or don’t bother. Graham went on to remind us that brands, in so far as they are owned at all, are owned by and co-created with our customers. Advertising can offer a message to customers, but they provide the expression of a brand. This was a preface to talking about an increasingly chaotic marketplace, with increasingly hard-to-manage purchase processes. Services like Amazon reviews and TripAdvisor (four presenters would make this point) saturate customers with information, and give them a kind of vigilante power to comment on and define brands. Consequentially, they experience a number of “moments of deflection” in our sales funnels. Our control is lessened, and failure to engage can negatively-impact buying decisions increasingly poorly. The clearest example given was the failure of NatWest’s “caring bank” campaign, where staff in branches, customer support, and online presences didn’t align. A discontinuity of experience basically made the campaign worthless, and disgruntled customers talked about it loudly on social media. This in turn presented an opportunity to engage and show caring, but that wasn’t taken. What I took away was that brand (co)creation is ongoing and needs monitoring and metrics. But reciprocally, given you get what you measure, strategy and metrics must include brand if any kind of branding is to work at all. Campaigns and messages must permeate product and service design. What that doesn’t mean (and Graham didn’t say it did) is putting Marketing at the top of the pyramid, and having them bawl demands at Product Management, Support, and Development like an entitled toddler. It’s going to have to be collaborative, and session 6 on internal comms handled this really well. The main thing missing here was substantiating data, and the main question I found myself chewing on was: if we’re building brands collaboratively and in the open, what about the cultural politics of trolling? 2 – Challenging our core beliefs about human behaviour, Mark Earls This was definitely the best show of the day. It was also some of the best content. Mark talked us through nudging, behavioural economics, and some key misconceptions around decision making. Basically, people aren’t rational, they’re petty, reactive, emotional sacks of meat, and they’ll go where they’re led. Comforting stuff. Examples given were the spread of the London Riots and the “discovery” of the mountains of Kong, and the popularity of Susan Boyle, which, in turn made me think about Per Mollerup’s concept of “social wayshowing”. Mark boiled his thoughts down into four key points which I completely failed to write down word for word: People do, then think – Changing minds to change behaviour doesn’t work. Post-rationalization rules the day. See also: mere exposure effects. Spock < Kirk - Emotional/intuitive comes first, then we rationalize impulses. The non-thinking, emotive, reactive processes run much faster than the deliberative ones. People are not really rational decision makers, so  intervening with information may not be appropriate. Maximisers or satisficers? – Related to the last point. People do not consistently, rationally, maximise. When faced with an abundance of choice, they prefer to satisfice than evaluate, and will often follow social leads rather than think. Things tend to converge – Behaviour trends to a consensus normal. When faced with choices people overwhelmingly just do what they see others doing. Humans are extraordinarily good at mirroring behaviours and receiving influence. People “outsource the cognitive load” of choices to the crowd. Mark’s headline quote was probably “the real influence happens at the table next to you”. Reference examples, word of mouth, and social influence are tremendously important, and so talking about product experiences may be more important than talking about products. This reminded me of Kathy Sierra’s “creating bad-ass users” concept of designing to make people more awesome rather than products they like. If we can expose user-awesome, and make sharing easy, we can normalise the behaviours we want. If we normalize the behaviours we want, people should make and post-rationalize the buying decisions we want.  Where we need to be: “A bigger boy made me do it” Where we are: “a wizard did it and ran away” However, it’s worth bearing in mind that some purchasing decisions are personal and informed rather than social and reactive. There’s a quadrant diagram, in fact. What was really interesting, though, towards the end of the talk, was some advice for working out how social your products might be. The standard technology adoption lifecycle graph is essentially about social product diffusion. So this idea isn’t really new. Geoffrey Moore’s “chasm” idea may not strictly apply. However, his concepts of beachheads and reference segments are exactly what is required to normalize and thus enable purchase decisions (behaviour change). The final thing is that in only very few categories does a better product actually affect purchase decision. Where the choice is personal and informed, this is true. But where it’s personal and impulsive, or in any way social, “better” is trumped by popularity, endorsement, or “point of sale salience”. UX, UCD, and e-commerce know this to be true. A better (and easier) experience will always beat “more features”. Easy to use, and easy to observe being used will beat “what the user says they want”. This made me think about the astounding stickiness of rational fallacies, “common sense” and the pathological willful simplifications of the media. Rational fallacies seem like they’re basically the heuristics we use for post-rationalization. If I were profoundly grimy and cynical, I’d suggest deploying a boat-load in our messaging, to see if they’re really as sticky and appealing as they look. 4 – Changing behaviour through communication, Stephen Donajgrodzki This was a fantastic follow up to Mark’s session. Stephen basically talked us through some tactics used in public information/health comms that implement the kind of behavioural theory Mark introduced. The session was largely about how to get people to do (good) things they’re predisposed not to do, and how communication can (and can’t) make positive interventions. A couple of things stood out, in particular “implementation intentions” and how they can be linked to goals. For example, in order to get people to check and test their smoke alarms (a goal intention, rarely actualized  an information campaign will attempt to link this activity to the clocks going back or forward (a strong implementation intention, well-actualized). The talk reinforced the idea that making behaviour changes easy and visible normalizes them and makes them more likely to succeed. To do this, they have to be embodied throughout a product and service cycle. Experiential disconnects undermine the normalization. So campaigns, products, and customer interactions must be aligned. This is underscored by the second section of the presentation, which talked about interventions and pre-conditions for change. Taking the examples of drug addiction and stopping smoking, Stephen showed us a framework for attempting (and succeeding or failing in) behaviour change. He noted that when the change is something people fundamentally want to do, and that is easy, this gets a to simpler. Coordinated, easily-observed environmental pressures create preconditions for change and build motivation. (price, pub smoking ban, ad campaigns, friend quitting, declining social acceptability) A triggering even leads to a change attempt. (getting a cold and panicking about how bad the cough is) Interventions can be made to enable an attempt (NHS services, public information, nicotine patches) If it succeeds – yay. If it fails, there’s strong negative enforcement. Triggering events seem largely personal, but messaging can intervene in the creation of preconditions and in supporting decisions. Stephen talked more about systems of thinking and “bounded rationality”. The idea being that to enable change you need to break through “automatic” thinking into “reflective” thinking. Disruption and emotion are great tools for this, but that is only the start of the process. It occurs to me that a great deal of market research is focused on determining triggers rather than analysing necessary preconditions. Although they are presumably related. The final section talked about setting goals. Marketing goals are often seen as deriving directly from business goals. However, marketing may be unable to deliver on these directly where decision and behaviour-change processes are involved. In those cases, marketing and communication goals should be to create preconditions. They should also consider priming and norms. Content marketing and brand awareness are good first steps here, as brands can be heuristics in decision making for choice-saturated consumers, or those seeking education. 5 – The power of engaged communities and how to build them, Harriet Minter (the Guardian) The meat of this was that you need to let communities define and establish themselves, and be quick to react to their needs. Harriet had been in charge of building the Guardian’s community sites, and learned a lot about how they come together, stabilize  grow, and react. Crucially, they can’t be about sales or push messaging. A community is not just an audience. It’s essential to start with what this particular segment or tribe are interested in, then what they want to hear. Eventually you can consider – in light of this – what they might want to buy, but you can’t start with the product. A community won’t cohere around one you’re pushing. Her tips for community building were (again, sorry, not verbatim): Set goals Have some targets. Community building sounds vague and fluffy, but you can have (and adjust) concrete goals. Think like a start-up This is the “lean” stuff. Try things, fail quickly, respond. Don’t restrict platforms Let the audience choose them, and be aware of their differences. For example, LinkedIn is very different to Twitter. Track your stats Related to the first point. Keeping an eye on the numbers lets you respond. They should be qualified, however. If you want a community of enterprise decision makers, headcount alone may be a bad metric – have you got CIOs, or just people who want to get jobs by mingling with CIOs? Build brand advocates Do things to involve people and make them awesome, and they’ll cheer-lead for you. The last part really got my attention. Little bits of drive-by kindness go a long way. But more than that, genuinely helping people turns them into powerful advocates. Harriet gave an example of the Guardian engaging with an aspiring journalist on its Q&A forums. Through a series of serendipitous encounters he became a BBC producer, and now enthusiastically speaks up for the Guardian community sites. Cultivating many small, authentic, influential voices may have a better pay-off than schmoozing the big guys. This could be particularly important in the context of Mark and Stephen’s models of social, endorsement-led, and example-led decision making. There’s a lot here I haven’t covered, and it may be worth some follow-up on community building. Thoughts I was quite sceptical of nudge theory and behavioural economics. First off it sounds too good to be true, and second it sounds too sinister to permit. But I haven’t done the background reading. So I’m going to, and if it seems to hold real water, and if it’s possible to do it ethically (Stephen’s presentations suggests it may be) then it’s probably worth exploring. The message seemed to be: change what people do, and they’ll work out why afterwards. Moreover, the people around them will do it too. Make the things you want them to do extraordinarily easy and very, very visible. Normalize and support the decisions you want them to make, and they’ll make them. In practice this means not talking about the thing, but showing the user-awesome. Glib? Perhaps. But it feels worth considering. Also, if I ever run a marketing conference, I’m going to ban speakers from using examples from Apple. Quite apart from not being consistently generalizable, it’s becoming an irritating cliché.

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  • CodePlex Daily Summary for Friday, June 17, 2011

    CodePlex Daily Summary for Friday, June 17, 2011Popular ReleasesPowerGUI Visual Studio Extension: PowerGUI VSX 1.3.5: Changes - VS SDK no longer required to be installed (a bug in v. 1.3.4).EnhSim: EnhSim 2.4.7 BETA: 2.4.7 BETAThis release supports WoW patch 4.1 at level 85 To use this release, you must have the Microsoft Visual C++ 2010 Redistributable Package installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=A7B7A05E-6DE6-4D3A-A423-37BF0912DB84 To use the GUI you must have the .NET 4.0 Framework installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=9cfb2d51-5ff4-4491-b0e5-b386f32c0992 - Updated the Stormst...Media Companion: MC 3.407b Weekly: Important! A movie rebuild & restart is required after installing this update. Fixes Movie Actor cache path settings should now be created correctly after rescrape or recrape specific TV 'The' will be moved to the end of TVShow titles when renaming if the 'ignore article' preference is enabled Improved the TVDB log details for the stream type returned by TVDB Right Clicking on a TVShow now gives the option to display episodes in a new window in aired date order - ideal to see where special...Gendering Add-In for Microsoft Office Word 2010: Gendering Add-In: This is the first stable Version of the Gendering Add-In. Unzip the package and start "setup.exe". The .reg file shows how to config an alternate path for suggestion table.TerrariViewer: TerrariViewer v3.1 [Terraria Inventory Editor]: This version adds tool tips. Almost every picture box you mouse over will tell you what item is in that box. I have also cleaned up the GUI a little more to make things easier on my end. There are various bug fixes including ones associated with opening different characters in the same instance of the program. As always, please bring any bugs you find to my attention.Kinect Paint: KinectPaint V1.0: This is version 1.0 of Kinect Paint. To run it, follow the steps: Install the Kinect SDK for Windows (available at http://research.microsoft.com/en-us/um/redmond/projects/kinectsdk/download.aspx) Connect your Kinect device to the computer and to the power. Download the Zip file. Unblock the Zip file by right clicking on it, and pressing the Unblock button in the file properties (if available). Extract the content of the Zip file. Run KinectPaint.exe.CommonLibrary.NET: CommonLibrary.NET - 0.9.7 Beta: A collection of very reusable code and components in C# 3.5 ranging from ActiveRecord, Csv, Command Line Parsing, Configuration, Holiday Calendars, Logging, Authentication, and much more. Samples in <root>\src\Lib\CommonLibrary.NET\Samples CommonLibrary.NET 0.9.7Documentation 6738 6503 New 6535 Enhancements 6583 6737DropBox Linker: DropBox Linker 1.2: Public sub-folders are now monitored for changes as well (thanks to mcm69) Automatic public sync folder detection (thanks to mcm69) Non-Latin and special characters encoded correctly in URLs Pop-ups are now slot-based (use first free slot and will never be overlapped — test it while previewing timeout) Public sync folder setting is hidden when auto-detected Timeout interval is displayed in popup previews A lot of major and minor code refactoring performed .NET Framework 4.0 Client...Terraria World Viewer: Version 1.3: Update June 15th Removed "Draw Markers" checkbox from main window because of redundancy/confusing. (Select all or no items from the Settings tab for the same effect.) Fixed Marker preferences not being saved. It is now possible to render more than one map without having to restart the application. World file will not be locked while the world is being rendered. Note: The World Viewer might render an inaccurate map or even crash if Terraria decides to modify the World file during the pro...MVC Controls Toolkit: Mvc Controls Toolkit 1.1.5 RC: Added Extended Dropdown allows a prompt item to be inserted as first element. RequiredAttribute, if present, trggers if no element is chosen Client side javascript function to set/get the values of DateTimeInput, TypedTextBox, TypedEditDisplay, and to bind/unbind a "change" handler The selected page in the pager is applied the attribute selected-page="selected" that can be used in the definition of CSS rules to style the selected page items controls now interpret a null value as an empr...Umbraco CMS: Umbraco CMS 5.0 CTP 1: Umbraco 5 Community Technology Preview Umbraco 5 will be the next version of everyone's favourite, friendly ASP.NET CMS that already powers over 100,000 websites worldwide. Try out our first CTP of version 5 today! If you're new to Umbraco and would like to get a quick low-down on our popular and easy-to-learn approach to content management, check out our intro video here. What's in the v5 CTP box? This is a preview version of version 5 and includes support for the following familiar Umbr...Coding4Fun Kinect Toolkit: Coding4Fun.Kinect Toolkit: Version 1.0Kinect Mouse Cursor: Kinect Mouse Cursor v1.0: The initial release of the Kinect Mouse Cursor project!patterns & practices: Project Silk: Project Silk Community Drop 11 - June 14, 2011: Changes from previous drop: Many code changes: please see the readme.mht for details. New "Client Data Management and Caching" chapter. Updated "Application Notifications" chapter. Updated "Architecture" chapter. Updated "jQuery UI Widget" chapter. Updated "Widget QuickStart" appendix and code. Guidance Chapters Ready for Review The Word documents for the chapters are included with the source code in addition to the CHM to help you provide feedback. The PDF is provided as a separat...Orchard Project: Orchard 1.2: Build: 1.2.41 Published: 6/14/2010 How to Install Orchard To install Orchard using Web PI, follow these instructions: http://www.orchardproject.net/docs/Installing-Orchard.ashx. Web PI will detect your hardware environment and install the application. Alternatively, to install the release manually, download the Orchard.Web.1.2.41.zip file. http://orchardproject.net/docs/Manually-installing-Orchard-zip-file.ashx The zip contents are pre-built and ready-to-run. Simply extract the contents o...Snippet Designer: Snippet Designer 1.4.0: Snippet Designer 1.4.0 for Visual Studio 2010 Change logSnippet Explorer ChangesReworked language filter UI to work better in the side bar. Added result count drop down which lets you choose how many results to see. Language filter and result count choices are persisted after Visual Studio is closed. Added file name to search criteria. Search is now case insensitive. Snippet Editor Changes Snippet Editor ChangesAdded menu option for the $end$ symbol which indicates where the c...Mobile Device Detection and Redirection: 1.0.4.1: Stable Release 51 Degrees.mobi Foundation is the best way to detect and redirect mobile devices and their capabilities on ASP.NET and is being used on thousands of websites worldwide. We’re highly confident in our software and we recommend all users update to this version. Changes to Version 1.0.4.1Changed the BlackberryHandler and BlackberryVersion6Handler to have equal CONFIDENCE values to ensure they both get a chance at detecting BlackBerry version 4&5 and version 6 devices. Prior to thi...Rawr: Rawr 4.1.06: This is the Downloadable WPF version of Rawr!For web-based version see http://elitistjerks.com/rawr.php You can find the version notes at: http://rawr.codeplex.com/wikipage?title=VersionNotes Rawr AddonWe now have a Rawr Official Addon for in-game exporting and importing of character data hosted on Curse. The Addon does not perform calculations like Rawr, it simply shows your exported Rawr data in wow tooltips and lets you export your character to Rawr (including bag and bank items) like Char...AcDown????? - Anime&Comic Downloader: AcDown????? v3.0 Beta6: ??AcDown?????????????,?????????????,????、????。?????Acfun????? ????32??64? Windows XP/Vista/7 ????????????? ??:????????Windows XP???,?????????.NET Framework 2.0???(x86)?.NET Framework 2.0???(x64),?????"?????????"??? ??v3.0 Beta6 ?????(imanhua.com)????? ???? ?? ??"????","?????","?????","????"?????? "????"?????"????????"?? ??????????? ?????????????? ?????????????/???? ?? ????Windows 7???????????? ????????? ?? ????????????? ???????/??????????? ???????????? ?? ?? ?????(imanh...Pulse: Pulse Beta 2: - Added new wallpapers provider http://wallbase.cc. Supports english search, multiple keywords* - Improved font rendering in Options window - Added "Set wallpaper as logon background" option* - Fixed crashes if there is no internet connection - Fixed: Rewalls downloads empty images sometimes - Added filters* Note 1: wallbase provider supports only english search. Rewalls provider supports only russian search but Pulse automatically translates your english keyword into russian using Google Tr...New ProjectsASP.NET Menu Extender for Unordered List ( UL ) HTML: The MenuExtender is an ASP.NET extender which will turn hierarchial HTML lists (rendered with UL and LI) into a multi-level dynamic cascading menu. Azure Proxy Handler: This project helps you to provide access onto your azure development application throught direct address like http://azureproxy.com (without port number). Even your application on unknown port. Also this application allows use HTTPS protocol.BD Simple Status: BD Simple Status is a straight-forward server up/down indication website. Cmic Reader: Cmic Reader is a reader allows you to download txt files form SkyDrive and read the txt files on windows phone 7. It support to read txt files in English and east Asia languages for example Chinese or Japanese in UTF 8 encoding. Coding4Fun Kinect Toolkit: kinect!EeRePeSIA: Esta si funciona....EIGHT.one - Tile-Based Browser Start Page: Windows-8-inspired, tile-based browser start pageEntityGraph: EntityGraph is a technology to separate generic structural operations from your data model. Examples are: copying/cloning, querying, and data validation. These operations can be applied to parts of your data model as defined by graph shapes. EventController: A control an event serviceInterceptor: Interceptor is an open source library used to intercept managed methods. The library can be used whenever an hook of a managed method is necessary. Currently Interceptor works only on 32 bit machine.Interval Tree: Interval Tree implementation for C# This is the data structure you need to store a lot of temporal data and retrieve it super fast by point in time or time range.Kinect Mouse Cursor: Kinect Mouse Cursor is a demo application that uses the Kinect for Windows SDK and its skeletal tracking features to allow a user to use their hands to control the Windows mouse cursor.Kinect Paint: Kinect Paint is a skeleton tracking application that allows you to become the paint brush!Learning: get more fun. :)lendlesscms: lendlesscmslendlesstools: lendlesstoolsLittle Wiki Plugins: Little wiki plugins is a small project for developing plugins for two popular wikis i.e. Dokuwiki and Tiddlywiki Mapas do Google: Estudando a API do Google Maps.MetroBackUp: MetroBackUp is an application for synchronization of directories. Thereby several pairs of directories, that shall be synchronized, can be grouped in jobs and updated together.mvcblogengine: ??ASP.NET MVC?BlogEngine???????????。MvcPipe: Facebook Bigpipe implementation for ASP.NET MVC. Allows to execute asynchronous actions to update the visible client UI at different times, improving perceived client latency.My Task List Rollup: Here I am again with a new utility for your SharePoint deployment – “My Task List Rollup”.NIntegra: NIntegra: Continuous Integration ServerPlusForum MSDN: A happy way to browse MSDN ForumsPopup Multi-Time Zone Clock: MultiClock provides a display of multiple analog clocks in various time zones. The application hides along the right side of the user's screen, and appears on mouse-over. It's developed in C# and uses components from http://www.codeproject.com/KB/miscctrl/yaac.aspxProject Jellybean, a kinect drivable lounge chair: Jellybean is a kinect drivable lounge chairRoboPowerCopy: A PowerShell "clone" of the famous "ROBOCOPY" tool. In fact I've adapted the funcionality of "robocopy" in PowerShell to provide you and myself a "robust file copy" tool.Silverlight TreeGrid: Silverlight TreeGrid is a component, that inherits DataGrid and adds the ability to display hierarchical data.simplemock-dot-net: SimpleMock is a mocking framework that is designed to be lightweight, simplistic, minimalistic, strongly typed and generally very easy to use via a Fluent API.SQL Server Replication Explorer: SQL Server Replication Explorer is a client tool for browsing through Microsoft SQL Server replication topology. It can also be used for troubleshooting and monitoring of the Microsoft SQL Server replication. System.Media.SoundPlayer example with ThreadPool: Play audio file (.wav, .mp3) with SoundPlayer class. I have already wrap it with ThreadPool, won't freeze your GUI. Grab it and see how .Net play an audio file.The Dot Net Download Manager: A fast and user friendly download manager that aims to keep it simple. The aim is to provide all the important features of commercial download managers while keeping it simple, functional and user friendly. The application is written in C# WPFTibiaPingFixer: TibiaPingFixer will reduce your online gaming latency significantly by increasing the frequency of TCP acknowledgements sent to the game server. For the technically minded, this is a script which will modify TCPAckFrequency. TimeOffManager: Time Off ManagerWeatherUS: WeatherUS

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  • Installing nGinX Reverse Proxy on CentOS 5

    - by heavymark
    I'm trying to install nGinX as a reverse proxy on CentOS 5 with apache. The instructions to do this are here: http://wiki.mediatemple.net/w/(dv):Configure_nginx_as_reverse_proxy_web_server Note- in the instructions, for the url to get nginx I'm using the following: http://nginx.org/download/nginx-1.0.10.tar.gz Now here is my problem. After installing the required packages and running .configure I get the following: checking for OS + Linux 2.6.18-028stab094.3 x86_64 checking for C compiler ... found + using GNU C compiler + gcc version: 4.1.2 20080704 (Red Hat 4.1.2-51) checking for gcc -pipe switch ... found checking for gcc builtin atomic operations ... found checking for C99 variadic macros ... found checking for gcc variadic macros ... found checking for unistd.h ... found checking for inttypes.h ... found checking for limits.h ... found checking for sys/filio.h ... not found checking for sys/param.h ... found checking for sys/mount.h ... found checking for sys/statvfs.h ... found checking for crypt.h ... found checking for Linux specific features checking for epoll ... found checking for sendfile() ... found checking for sendfile64() ... found checking for sys/prctl.h ... found checking for prctl(PR_SET_DUMPABLE) ... found checking for sched_setaffinity() ... found checking for crypt_r() ... found checking for sys/vfs.h ... found checking for nobody group ... found checking for poll() ... found checking for /dev/poll ... not found checking for kqueue ... not found checking for crypt() ... not found checking for crypt() in libcrypt ... found checking for F_READAHEAD ... not found checking for posix_fadvise() ... found checking for O_DIRECT ... found checking for F_NOCACHE ... not found checking for directio() ... not found checking for statfs() ... found checking for statvfs() ... found checking for dlopen() ... not found checking for dlopen() in libdl ... found checking for sched_yield() ... found checking for SO_SETFIB ... not found checking for SO_ACCEPTFILTER ... not found checking for TCP_DEFER_ACCEPT ... found checking for accept4() ... not found checking for int size ... 4 bytes checking for long size ... 8 bytes checking for long long size ... 8 bytes checking for void * size ... 8 bytes checking for uint64_t ... found checking for sig_atomic_t ... found checking for sig_atomic_t size ... 4 bytes checking for socklen_t ... found checking for in_addr_t ... found checking for in_port_t ... found checking for rlim_t ... found checking for uintptr_t ... uintptr_t found checking for system endianess ... little endianess checking for size_t size ... 8 bytes checking for off_t size ... 8 bytes checking for time_t size ... 8 bytes checking for setproctitle() ... not found checking for pread() ... found checking for pwrite() ... found checking for sys_nerr ... found checking for localtime_r() ... found checking for posix_memalign() ... found checking for memalign() ... found checking for mmap(MAP_ANON|MAP_SHARED) ... found checking for mmap("/dev/zero", MAP_SHARED) ... found checking for System V shared memory ... found checking for POSIX semaphores ... not found checking for POSIX semaphores in libpthread ... found checking for struct msghdr.msg_control ... found checking for ioctl(FIONBIO) ... found checking for struct tm.tm_gmtoff ... found checking for struct dirent.d_namlen ... not found checking for struct dirent.d_type ... found checking for PCRE library ... found checking for system md library ... not found checking for system md5 library ... not found checking for OpenSSL md5 crypto library ... found checking for sha1 in system md library ... not found checking for OpenSSL sha1 crypto library ... found checking for zlib library ... found creating objs/Makefile Configuration summary + using system PCRE library + OpenSSL library is not used + md5: using system crypto library + sha1: using system crypto library + using system zlib library nginx path prefix: "/usr/local/nginx" nginx binary file: "/usr/local/nginx/sbin/nginx" nginx configuration prefix: "/usr/local/nginx/conf" nginx configuration file: "/usr/local/nginx/conf/nginx.conf" nginx pid file: "/usr/local/nginx/logs/nginx.pid" nginx error log file: "/usr/local/nginx/logs/error.log" nginx http access log file: "/usr/local/nginx/logs/access.log" nginx http client request body temporary files: "client_body_temp" nginx http proxy temporary files: "proxy_temp" nginx http fastcgi temporary files: "fastcgi_temp" nginx http uwsgi temporary files: "uwsgi_temp" nginx http scgi temporary files: "scgi_temp" It says if you get errors to stop and make sure packages are installed. I didn't get errors but as you can see I got several "not founds". Are those considered errors? If so how do I resolve that. And as noted in the link, I cannot install through yum, because it wont work with plesk then. Thanks!

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  • DEV C ++ Error: expected declaration before '}' token

    - by Francesca
    What does this mean? My program goes like this: (NOTE: The line that has the error was the line coming before case 2.) case 1: { cout<< "C * H * E * M * I * S * T * R * Y \n\n"; cout<< "1) What is the valence electron configuration of Selenium (Se)?\n\n"; cout<< "\na) 1s2 2s2 2p6 3s2\n\n"; cout<< "\nb) 1s2 2s2 2p2\n\n"; cout<< "\nc)4s2 4p4\n\n"; cout<< "\nd) 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p5\n\n"; cout<< "Enter your answer:\n"; cin>> answer; if (answer == 'c') { cout<<"Your answer is correct. Please press the enter key to proceed to the next question.\n\n"; } else cout<< "The correct answer is C. Please press the enter key to proceed to the next question.\n\n"; getch (); } getch (); cout<< "2) Which element yields the biggest atomic radius?\n\n"; cout<< "\na) Ca\n\n"; cout<< "\nb) Xe\n\n"; cout<< "\nc) B\n\n"; cout<< "\nd) Cs\n\n"; cout<< "Enter your answer:\n"; cin>> answer; if (answer == 'd') { cout<< "Your answer is correct. Please press the enter key to proceed to the next question.\n\n"; } else cout<< "The correct answer is D. Please press the enter key to proceed to the next question.\n\n"; getch (); } cout<< "3) Name the ionic compound K2 Cr2 O7\n\n"; cout<< "\na) potassium chloride\n\n"; cout<< "\nb) potassium carbonate\n\n"; cout<< "\nc) potassium chromite\n\n"; cout<< "\nd) potassium chromate\n\n"; cout<< "Enter your answer:\n"; cin>> answer; if (answer == 'd') { cout<< "Your answer is correct. Please press the enter key to proceed to the next question.\n\n"; } else cout<< "The correct answer is D. Please press the enter key to proceed to the next question.\n\n"; getch (); } } case 2: { cout<< "G * E * O * M * E * T * R * Y \n\n"; The error, as noted in the title is expected declaration before '}' token at the line noted in my opening paragraph.

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  • I don't understand how work call_once

    - by SABROG
    Please help me understand how work call_once Here is thread-safe code. I don't understand why this need Thread Local Storage and global_epoch variables. Variable _fast_pthread_once_per_thread_epoch can be changed to constant/enum like {FAST_PTHREAD_ONCE_INIT, BEING_INITIALIZED, FINISH_INITIALIZED}. Why needed count calls in global_epoch? I think this code can be rewriting with logc: if flag FINISH_INITIALIZED do nothing, else go to block with mutexes and this all. #ifndef FAST_PTHREAD_ONCE_H #define FAST_PTHREAD_ONCE_H #include #include typedef sig_atomic_t fast_pthread_once_t; #define FAST_PTHREAD_ONCE_INIT SIG_ATOMIC_MAX extern __thread fast_pthread_once_t _fast_pthread_once_per_thread_epoch; #ifdef __cplusplus extern "C" { #endif extern void fast_pthread_once( pthread_once_t *once, void (*func)(void) ); inline static void fast_pthread_once_inline( fast_pthread_once_t *once, void (*func)(void) ) { fast_pthread_once_t x = *once; /* unprotected access */ if ( x _fast_pthread_once_per_thread_epoch ) { fast_pthread_once( once, func ); } } #ifdef __cplusplus } #endif #endif FAST_PTHREAD_ONCE_H Source fast_pthread_once.c The source is written in C. The lines of the primary function are numbered for reference in the subsequent correctness argument. #include "fast_pthread_once.h" #include static pthread_mutex_t mu = PTHREAD_MUTEX_INITIALIZER; /* protects global_epoch and all fast_pthread_once_t writes */ static pthread_cond_t cv = PTHREAD_COND_INITIALIZER; /* signalled whenever a fast_pthread_once_t is finalized */ #define BEING_INITIALIZED (FAST_PTHREAD_ONCE_INIT - 1) static fast_pthread_once_t global_epoch = 0; /* under mu */ __thread fast_pthread_once_t _fast_pthread_once_per_thread_epoch; static void check( int x ) { if ( x == 0 ) abort(); } void fast_pthread_once( fast_pthread_once_t *once, void (*func)(void) ) { /*01*/ fast_pthread_once_t x = *once; /* unprotected access */ /*02*/ if ( x _fast_pthread_once_per_thread_epoch ) { /*03*/ check( pthread_mutex_lock(µ) == 0 ); /*04*/ if ( *once == FAST_PTHREAD_ONCE_INIT ) { /*05*/ *once = BEING_INITIALIZED; /*06*/ check( pthread_mutex_unlock(µ) == 0 ); /*07*/ (*func)(); /*08*/ check( pthread_mutex_lock(µ) == 0 ); /*09*/ global_epoch++; /*10*/ *once = global_epoch; /*11*/ check( pthread_cond_broadcast(&cv;) == 0 ); /*12*/ } else { /*13*/ while ( *once == BEING_INITIALIZED ) { /*14*/ check( pthread_cond_wait(&cv;, µ) == 0 ); /*15*/ } /*16*/ } /*17*/ _fast_pthread_once_per_thread_epoch = global_epoch; /*18*/ check (pthread_mutex_unlock(µ) == 0); } } This code from BOOST: #ifndef BOOST_THREAD_PTHREAD_ONCE_HPP #define BOOST_THREAD_PTHREAD_ONCE_HPP // once.hpp // // (C) Copyright 2007-8 Anthony Williams // // Distributed under the Boost Software License, Version 1.0. (See // accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) #include #include #include #include "pthread_mutex_scoped_lock.hpp" #include #include #include namespace boost { struct once_flag { boost::uintmax_t epoch; }; namespace detail { BOOST_THREAD_DECL boost::uintmax_t& get_once_per_thread_epoch(); BOOST_THREAD_DECL extern boost::uintmax_t once_global_epoch; BOOST_THREAD_DECL extern pthread_mutex_t once_epoch_mutex; BOOST_THREAD_DECL extern pthread_cond_t once_epoch_cv; } #define BOOST_ONCE_INITIAL_FLAG_VALUE 0 #define BOOST_ONCE_INIT {BOOST_ONCE_INITIAL_FLAG_VALUE} // Based on Mike Burrows fast_pthread_once algorithm as described in // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2444.html template void call_once(once_flag& flag,Function f) { static boost::uintmax_t const uninitialized_flag=BOOST_ONCE_INITIAL_FLAG_VALUE; static boost::uintmax_t const being_initialized=uninitialized_flag+1; boost::uintmax_t const epoch=flag.epoch; boost::uintmax_t& this_thread_epoch=detail::get_once_per_thread_epoch(); if(epoch #endif I right understand, boost don't use atomic operation, so code from boost not thread-safe?

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  • Function calls not working in my page

    - by Vivek Dragon
    I made an select menu that works with the google-font-Api. I made to function in JSBIN here is my work http://jsbin.com/ocutuk/18/ But when i made the copy of my code in a html page its not even loading the font names in page. i tried to make it work but still it is in dead end. This is my html code <!DOCTYPE html> <html> <head> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"> </script> <meta charset=utf-8 /> <title>FONT API</title> <script> function SetFonts(fonts) { for (var i = 0; i < fonts.items.length; i++) { $('#styleFont') .append($("<option></option>") .attr("value", fonts.items[i].family) .text(fonts.items[i].family)); } } var script = document.createElement('script'); script.src = 'https://www.googleapis.com/webfonts/v1/webfonts?key=AIzaSyB8Ua6XIfe-gqbkE8P3XL4spd0x8Ft7eWo&callback=SetFonts'; document.body.appendChild(script); WebFontConfig = { google: { families: ['ABeeZee', 'Abel', 'Abril Fatface', 'Aclonica', 'Acme', 'Actor', 'Adamina', 'Advent Pro', 'Aguafina Script', 'Akronim', 'Aladin', 'Aldrich', 'Alegreya', 'Alegreya SC', 'Alex Brush', 'Alfa Slab One', 'Alice', 'Alike', 'Alike Angular', 'Allan', 'Allerta', 'Allerta Stencil', 'Allura', 'Almendra', 'Almendra Display', 'Almendra SC', 'Amarante', 'Amaranth', 'Amatic SC', 'Amethysta', 'Anaheim', 'Andada', 'Andika', 'Angkor', 'Annie Use Your Telescope', 'Anonymous Pro', 'Antic', 'Antic Didone', 'Antic Slab', 'Anton', 'Arapey', 'Arbutus', 'Arbutus Slab', 'Architects Daughter', 'Archivo Black', 'Archivo Narrow', 'Arimo', 'Arizonia', 'Armata', 'Artifika', 'Arvo', 'Asap', 'Asset', 'Astloch', 'Asul', 'Atomic Age', 'Aubrey', 'Audiowide', 'Autour One', 'Average', 'Average Sans', 'Averia Gruesa Libre', 'Averia Libre', 'Averia Sans Libre', 'Averia Serif Libre', 'Bad Script', 'Balthazar', 'Bangers', 'Basic', 'Battambang', 'Baumans', 'Bayon', 'Belgrano', 'Belleza', 'BenchNine', 'Bentham', 'Berkshire Swash', 'Bevan', 'Bigelow Rules', 'Bigshot One', 'Bilbo', 'Bilbo Swash Caps', 'Bitter', 'Black Ops One', 'Bokor', 'Bonbon', 'Boogaloo', 'Bowlby One', 'Bowlby One SC', 'Brawler', 'Bree Serif', 'Bubblegum Sans', 'Bubbler One', 'Buda', 'Buenard', 'Butcherman', 'Butterfly Kids', 'Cabin', 'Cabin Condensed', 'Cabin Sketch', 'Caesar Dressing', 'Cagliostro', 'Calligraffitti', 'Cambo', 'Candal', 'Cantarell', 'Cantata One', 'Cantora One', 'Capriola', 'Cardo', 'Carme', 'Carrois Gothic', 'Carrois Gothic SC', 'Carter One', 'Caudex', 'Cedarville Cursive', 'Ceviche One', 'Changa One', 'Chango', 'Chau Philomene One', 'Chela One', 'Chelsea Market', 'Chenla', 'Cherry Cream Soda', 'Cherry Swash', 'Chewy', 'Chicle', 'Chivo', 'Cinzel', 'Cinzel Decorative', 'Clicker Script', 'Coda', 'Coda Caption', 'Codystar', 'Combo', 'Comfortaa', 'Coming Soon', 'Concert One', 'Condiment', 'Content', 'Contrail One', 'Convergence', 'Cookie', 'Copse', 'Corben', 'Courgette', 'Cousine', 'Coustard', 'Covered By Your Grace', 'Crafty Girls', 'Creepster', 'Crete Round', 'Crimson Text', 'Croissant One', 'Crushed', 'Cuprum', 'Cutive', 'Cutive Mono']} }; (function() { var wf = document.createElement('script'); wf.src = ('https:' == document.location.protocol ? 'https' : 'http') + '://ajax.googleapis.com/ajax/libs/webfont/1/webfont.js'; wf.type = 'text/javascript'; wf.async = 'true'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(wf, s); })(); $("#styleFont").change(function (){ var id =$('#styleFont option' +':selected').val(); $("#custom_text").css('font-family',id); }); </script> <style> #custom_text { font-family: Arial; resize: none; margin-top: 20px; width: 500px; } #styleFont { width: 100px; } </style> </head> <body> <select id="styleFont"> </select><br> <textarea id="custom_text"></textarea> </body> </html> How can i make it work. Whats the mistake i am making here.

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  • Why might a System.String object not cache its hash code?

    - by Dan Tao
    A glance at the source code for string.GetHashCode using Reflector reveals the following (for mscorlib.dll version 4.0): public override unsafe int GetHashCode() { fixed (char* str = ((char*) this)) { char* chPtr = str; int num = 0x15051505; int num2 = num; int* numPtr = (int*) chPtr; for (int i = this.Length; i > 0; i -= 4) { num = (((num << 5) + num) + (num >> 0x1b)) ^ numPtr[0]; if (i <= 2) { break; } num2 = (((num2 << 5) + num2) + (num2 >> 0x1b)) ^ numPtr[1]; numPtr += 2; } return (num + (num2 * 0x5d588b65)); } } Now, I realize that the implementation of GetHashCode is not specified and is implementation-dependent, so the question "is GetHashCode implemented in the form of X or Y?" is not really answerable. I'm just curious about a few things: If Reflector has disassembled the DLL correctly and this is the implementation of GetHashCode (in my environment), am I correct in interpreting this code to indicate that a string object, based on this particular implementation, would not cache its hash code? Assuming the answer is yes, why would this be? It seems to me that the memory cost would be minimal (one more 32-bit integer, a drop in the pond compared to the size of the string itself) whereas the savings would be significant, especially in cases where, e.g., strings are used as keys in a hashtable-based collection like a Dictionary<string, [...]>. And since the string class is immutable, it isn't like the value returned by GetHashCode will ever even change. What could I be missing? UPDATE: In response to Andras Zoltan's closing remark: There's also the point made in Tim's answer(+1 there). If he's right, and I think he is, then there's no guarantee that a string is actually immutable after construction, therefore to cache the result would be wrong. Whoa, whoa there! This is an interesting point to make (and yes it's very true), but I really doubt that this was taken into consideration in the implementation of GetHashCode. The statement "therefore to cache the result would be wrong" implies to me that the framework's attitude regarding strings is "Well, they're supposed to be immutable, but really if developers want to get sneaky they're mutable so we'll treat them as such." This is definitely not how the framework views strings. It fully relies on their immutability in so many ways (interning of string literals, assignment of all zero-length strings to string.Empty, etc.) that, basically, if you mutate a string, you're writing code whose behavior is entirely undefined and unpredictable. I guess my point is that for the author(s) of this implementation to worry, "What if this string instance is modified between calls, even though the class as it is publicly exposed is immutable?" would be like for someone planning a casual outdoor BBQ to think to him-/herself, "What if someone brings an atomic bomb to the party?" Look, if someone brings an atom bomb, party's over.

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  • How to design a high-level application protocol for metadata syncing between devices and server?

    - by Jaanus
    I am looking for guidance on how to best think about designing a high-level application protocol to sync metadata between end-user devices and a server. My goal: the user can interact with the application data on any device, or on the web. The purpose of this protocol is to communicate changes made on one endpoint to other endpoints through the server, and ensure all devices maintain a consistent picture of the application data. If user makes changes on one device or on the web, the protocol will push data to the central repository, from where other devices can pull it. Some other design thoughts: I call it "metadata syncing" because the payloads will be quite small, in the form of object IDs and small metadata about those ID-s. When client endpoints retrieve new metadata over this protocol, they will fetch actual object data from an external source based on this metadata. Fetching the "real" object data is out of scope, I'm only talking about metadata syncing here. Using HTTP for transport and JSON for payload container. The question is basically about how to best design the JSON payload schema. I want this to be easy to implement and maintain on the web and across desktop and mobile devices. The best approach feels to be simple timer- or event-based HTTP request/response without any persistent channels. Also, you should not have a PhD to read it, and I want my spec to fit on 2 pages, not 200. Authentication and security are out of scope for this question: assume that the requests are secure and authenticated. The goal is eventual consistency of data on devices, it is not entirely realtime. For example, user can make changes on one device while being offline. When going online again, user would perform "sync" operation to push local changes and retrieve remote changes. Having said that, the protocol should support both of these modes of operation: Starting from scratch on a device, should be able to pull the whole metadata picture "sync as you go". When looking at the data on two devices side by side and making changes, should be easy to push those changes as short individual messages which the other device can receive near-realtime (subject to when it decides to contact server for sync). As a concrete example, you can think of Dropbox (it is not what I'm working on, but it helps to understand the model): on a range of devices, the user can manage a files and folders—move them around, create new ones, remove old ones etc. And in my context the "metadata" would be the file and folder structure, but not the actual file contents. And metadata fields would be something like file/folder name and time of modification (all devices should see the same time of modification). Another example is IMAP. I have not read the protocol, but my goals (minus actual message bodies) are the same. Feels like there are two grand approaches how this is done: transactional messages. Each change in the system is expressed as delta and endpoints communicate with those deltas. Example: DVCS changesets. REST: communicating the object graph as a whole or in part, without worrying so much about the individual atomic changes. What I would like in the answers: Is there anything important I left out above? Constraints, goals? What is some good background reading on this? (I realize this is what many computer science courses talk about at great length and detail... I am hoping to short-circuit it by looking at some crash course or nuggets.) What are some good examples of such protocols that I could model after, or even use out of box? (I mention Dropbox and IMAP above... I should probably read the IMAP RFC.)

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  • xts error - order.by requires an appropriate time-based object

    - by Samo
    I can not resolve why error in simple creation of xts object xts(rep(0, NROW(TICK.NYSE)), order.by = index(TICK.NYSE)) Error in xts(rep(0, NROW(TICK.NYSE)), order.by = index(TICK.NYSE)) : order.by requires an appropriate time-based object appeared while this was working perfectly 14 days ago when I last used the same code (since then the only difference is that TICK.NYSE grow in length since data was added since then). More details below: > Sys.getenv("TZ") [1] "EST" > tail(xts(rep(0, NROW(TICK.NYSE)), order.by = index(TICK.NYSE))) Error in xts(rep(0, NROW(TICK.NYSE)), order.by = index(TICK.NYSE)) : order.by requires an appropriate time-based object > class(index(TICK.NYSE["T09:30/T09:31"])) [1] "POSIXct" > tail(xts(rep(0, NROW(tail(TICK.NYSE))), order.by = index(tail(TICK.NYSE)))) Error in xts(rep(0, NROW(tail(TICK.NYSE))), order.by = index(tail(TICK.NYSE))) : order.by requires an appropriate time-based object > tail(TICK.NYSE) TICK-NYSE.Open TICK-NYSE.High TICK-NYSE.Low TICK-NYSE.Close 2012-03-15 14:54:00 -278 -89 -299 -89 2012-03-15 14:55:00 -89 427 -89 201 2012-03-15 14:56:00 201 318 30 234 2012-03-15 14:57:00 234 242 -222 -64 2012-03-15 14:58:00 -64 346 -82 346 2012-03-15 14:59:00 346 525 36 525 TICK-NYSE.Volume TICK-NYSE.WAP TICK-NYSE.hasGaps 2012-03-15 14:54:00 0 0 0 2012-03-15 14:55:00 0 0 0 2012-03-15 14:56:00 0 0 0 2012-03-15 14:57:00 0 0 0 2012-03-15 14:58:00 0 0 0 2012-03-15 14:59:00 0 0 0 TICK-NYSE.Count 2012-03-15 14:54:00 31 2012-03-15 14:55:00 31 2012-03-15 14:56:00 31 2012-03-15 14:57:00 31 2012-03-15 14:58:00 29 2012-03-15 14:59:00 30 > str(TICK.NYSE) An ‘xts’ object from 2011-01-18 09:30:00 to 2012-03-15 14:59:00 containing: Data: num [1:114090, 1:8] -5 -144 24 -148 -184 -77 20 121 111 -60 ... - attr(*, "dimnames")=List of 2 ..$ : NULL ..$ : chr [1:8] "TICK-NYSE.Open" "TICK-NYSE.High" "TICK-NYSE.Low" "TICK-NYSE.Close" ... Indexed by objects of class: [POSIXct,POSIXt] TZ: xts Attributes: List of 4 $ from : chr "20110119 23:59:59" $ to : chr "20110124 23:59:59" $ src : chr "IB" $ updated: POSIXct[1:1], format: "2012-01-19 02:34:52" > str(index(TICK.NYSE)) Class 'POSIXct' atomic [1:114090] 1.3e+09 1.3e+09 1.3e+09 1.3e+09 1.3e+09 ... ..- attr(*, "tzone")= chr "" ..- attr(*, "tclass")= chr [1:2] "POSIXct" "POSIXt" > Sys.getenv("TZ") [1] "EST" > tail(index(TICK.NYSE)) [1] "2012-03-15 14:54:00 EST" "2012-03-15 14:55:00 EST" [3] "2012-03-15 14:56:00 EST" "2012-03-15 14:57:00 EST" [5] "2012-03-15 14:58:00 EST" "2012-03-15 14:59:00 EST" > head(index(TICK.NYSE)) [1] "2011-01-18 09:30:00 EST" "2011-01-18 09:31:00 EST" [3] "2011-01-18 09:32:00 EST" "2011-01-18 09:33:00 EST" [5] "2011-01-18 09:34:00 EST" "2011-01-18 09:35:00 EST" > Sys.info() sysname "Linux" release "3.0.0-16-generic" version "#28-Ubuntu SMP Fri Jan 27 17:44:39 UTC 2012" > sessionInfo() R version 2.14.1 (2011-12-22) Platform: x86_64-pc-linux-gnu (64-bit) locale: [1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C [3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8 [5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8 [7] LC_PAPER=en_US.UTF-8 LC_NAME=en_US.UTF-8 [9] LC_ADDRESS=en_US.UTF-8 LC_TELEPHONE=en_US.UTF-8 [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=en_US.UTF-8 attached base packages: [1] stats graphics grDevices utils datasets methods base other attached packages: [1] lattice_0.20-0 multicore_0.1-7 [3] doSNOW_1.0.5 snow_0.3-8 [5] doRedis_1.0.4 rredis_1.6.3 [7] foreach_1.3.2 codetools_0.2-8 [9] iterators_1.0.5 PerformanceAnalytics_1.0.3.3 [11] quantstrat_0.6.1 blotter_0.8.4 [13] twsInstrument_1.3-3 FinancialInstrument_0.10.6 [15] IBrokers_0.9-6 quantmod_0.3-18 [17] TTR_0.21-0 xts_0.8-4 [19] Defaults_1.1-1 strucchange_1.4-6 [21] sandwich_2.2-8 zoo_1.7-7 [23] rj_1.0.2-5 loaded via a namespace (and not attached): [1] grid_2.14.1 tools_2.14.1 > dput(tail(TICK.NYSE)) structure(c(-385, -213, -42, -334, -233, -111, -121, 20, -14, -125, -73, 265, -583, -269, -426, -520, -443, -440, -213, -42, -334, -233, -111, 119, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 31, 31, 30, 30, 31, 31), class = c("xts", "zoo" ), .indexCLASS = c("POSIXct", "POSIXt"), .indexTZ = "", from = "20110119 23:59:59", to = "20110124 23:59:59", src = "IB", updated = structure(1326958492.96405, class = c("POSIXct", "POSIXt")), index = structure(c(1331927640, 1331927700, 1331927760, 1331927820, 1331927880, 1331927940), tzone = "", tclass = c("POSIXct", "POSIXt")), .Dim = c(6L, 8L), .Dimnames = list(NULL, c("TICK-NYSE.Open", "TICK-NYSE.High", "TICK-NYSE.Low", "TICK-NYSE.Close", "TICK-NYSE.Volume", "TICK-NYSE.WAP", "TICK-NYSE.hasGaps", "TICK-NYSE.Count")))

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  • Testing for Adjacent Cells In a Multi-level Grid

    - by Steve
    I'm designing an algorithm to test whether cells on a grid are adjacent or not. The catch is that the cells are not on a flat grid. They are on a multi-level grid such as the one drawn below. Level 1 (Top Level) | - - - - - | | A | B | C | | - - - - - | | D | E | F | | - - - - - | | G | H | I | | - - - - - | Level 2 | -Block A- | -Block B- | | 1 | 2 | 3 | 1 | 2 | 3 | | - - - - - | - - - - - | | 4 | 5 | 6 | 4 | 5 | 6 | ... | - - - - - | - - - - - | | 7 | 8 | 9 | 7 | 8 | 9 | | - - - - - | - - - - - | | -Block D- | -Block E- | | 1 | 2 | 3 | 1 | 2 | 3 | | - - - - - | - - - - - | | 4 | 5 | 6 | 4 | 5 | 6 | ... | - - - - - | - - - - - | | 7 | 8 | 9 | 7 | 8 | 9 | | - - - - - | - - - - - | . . . . . . This diagram is simplified from my actual need but the concept is the same. There is a top level block with many cells within it (level 1). Each block is further subdivided into many more cells (level 2). Those cells are further subdivided into level 3, 4 and 5 for my project but let's just stick to two levels for this question. I'm receiving inputs for my function in the form of "A8, A9, B7, D3". That's a list of cell Ids where each cell Id has the format (level 1 id)(level 2 id). Let's start by comparing just 2 cells, A8 and A9. That's easy because they are in the same block. private static RelativePosition getRelativePositionInTheSameBlock(String v1, String v2) { RelativePosition relativePosition; if( v1-v2 == -1 ) { relativePosition = RelativePosition.LEFT_OF; } else if (v1-v2 == 1) { relativePosition = RelativePosition.RIGHT_OF; } else if (v1-v2 == -BLOCK_WIDTH) { relativePosition = RelativePosition.TOP_OF; } else if (v1-v2 == BLOCK_WIDTH) { relativePosition = RelativePosition.BOTTOM_OF; } else { relativePosition = RelativePosition.NOT_ADJACENT; } return relativePosition; } An A9 - B7 comparison could be done by checking if A is a multiple of BLOCK_WIDTH and whether B is (A-BLOCK_WIDTH+1). Either that or just check naively if the A/B pair is 3-1, 6-4 or 9-7 for better readability. For B7 - D3, they are not adjacent but D3 is adjacent to A9 so I can do a similar adjacency test as above. So getting away from the little details and focusing on the big picture. Is this really the best way to do it? Keeping in mind the following points: I actually have 5 levels not 2, so I could potentially get a list like "A8A1A, A8A1B, B1A2A, B1A2B". Adding a new cell to compare still requires me to compare all the other cells before it (seems like the best I could do for this step is O(n)) The cells aren't all 3x3 blocks, they're just that way for my example. They could be MxN blocks with different M and N for different levels. In my current implementation above, I have separate functions to check adjacency if the cells are in the same blocks, if they are in separate horizontally adjacent blocks or if they are in separate vertically adjacent blocks. That means I have to know the position of the two blocks at the current level before I call one of those functions for the layer below. Judging by the complexity of having to deal with mulitple functions for different edge cases at different levels and having 5 levels of nested if statements. I'm wondering if another design is more suitable. Perhaps a more recursive solution, use of other data structures, or perhaps map the entire multi-level grid to a single-level grid (my quick calculations gives me about 700,000+ atomic cell ids). Even if I go that route, mapping from multi-level to single level is a non-trivial task in itself.

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  • Mapping UrlEncoded POST Values in ASP.NET Web API

    - by Rick Strahl
    If there's one thing that's a bit unexpected in ASP.NET Web API, it's the limited support for mapping url encoded POST data values to simple parameters of ApiController methods. When I first looked at this I thought I was doing something wrong, because it seems mighty odd that you can bind query string values to parameters by name, but can't bind POST values to parameters in the same way. To demonstrate here's a simple example. If you have a Web API method like this:[HttpGet] public HttpResponseMessage Authenticate(string username, string password) { …} and then hit with a URL like this: http://localhost:88/samples/authenticate?Username=ricks&Password=sekrit it works just fine. The query string values are mapped to the username and password parameters of our API method. But if you now change the method to work with [HttpPost] instead like this:[HttpPost] public HttpResponseMessage Authenticate(string username, string password) { …} and hit it with a POST HTTP Request like this: POST http://localhost:88/samples/authenticate HTTP/1.1 Host: localhost:88 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Content-type: application/x-www-form-urlencoded Content-Length: 30 Username=ricks&Password=sekrit you'll find that while the request works, it doesn't actually receive the two string parameters. The username and password parameters are null and so the method is definitely going to fail. When I mentioned this over Twitter a few days ago I got a lot of responses back of why I'd want to do this in the first place - after all HTML Form submissions are the domain of MVC and not WebAPI which is a valid point. However, the more common use case is using POST Variables with AJAX calls. The following is quite common for passing simple values:$.post(url,{ Username: "Rick", Password: "sekrit" },function(result) {…}); but alas that doesn't work. How ASP.NET Web API handles Content Bodies Web API supports parsing content data in a variety of ways, but it does not deal with multiple posted content values. In effect you can only post a single content value to a Web API Action method. That one parameter can be very complex and you can bind it in a variety of ways, but ultimately you're tied to a single POST content value in your parameter definition. While it's possible to support multiple parameters on a POST/PUT operation, only one parameter can be mapped to the actual content - the rest have to be mapped to route values or the query string. Web API treats the whole request body as one big chunk of data that is sent to a Media Type Formatter that's responsible for de-serializing the content into whatever value the method requires. The restriction comes from async nature of Web API where the request data is read only once inside of the formatter that retrieves and deserializes it. Because it's read once, checking for content (like individual POST variables) first is not possible. However, Web API does provide a couple of ways to access the form POST data: Model Binding - object property mapping to bind POST values FormDataCollection - collection of POST keys/values ModelBinding POST Values - Binding POST data to Object Properties The recommended way to handle POST values in Web API is to use Model Binding, which maps individual urlencoded POST values to properties of a model object provided as the parameter. Model binding requires a single object as input to be bound to the POST data, with each POST key that matches a property name (including nested properties like Address.Street) being mapped and updated including automatic type conversion of simple types. This is a very nice feature - and a familiar one from MVC - that makes it very easy to have model objects mapped directly from inbound data. The obvious drawback with Model Binding is that you need a model for it to work: You have to provide a strongly typed object that can receive the data and this object has to map the inbound data. To rewrite the example above to use ModelBinding I have to create a class maps the properties that I need as parameters:public class LoginData { public string Username { get; set; } public string Password { get; set; } } and then accept the data like this in the API method:[HttpPost] public HttpResponseMessage Authenticate(LoginData login) { string username = login.Username; string password = login.Password; … } This works fine mapping the POST values to the properties of the login object. As a side benefit of this method definition, the method now also allows posting of JSON or XML to the same endpoint. If I change my request to send JSON like this: POST http://localhost:88/samples/authenticate HTTP/1.1 Host: localhost:88 Accept: application/jsonContent-type: application/json Content-Length: 40 {"Username":"ricks","Password":"sekrit"} it works as well and transparently, courtesy of the nice Content Negotiation features of Web API. There's nothing wrong with using Model binding and in fact it's a common practice to use (view) model object for inputs coming back from the client and mapping them into these models. But it can be  kind of a hassle if you have AJAX applications with a ton of backend hits, especially if many methods are very atomic and focused and don't effectively require a model or view. Not always do you have to pass structured data, but sometimes there are just a couple of simple response values that need to be sent back. If all you need is to pass a couple operational parameters, creating a view model object just for parameter purposes seems like overkill. Maybe you can use the query string instead (if that makes sense), but if you can't then you can often end up with a plethora of 'message objects' that serve no further  purpose than to make Model Binding work. Note that you can accept multiple parameters with ModelBinding so the following would still work:[HttpPost] public HttpResponseMessage Authenticate(LoginData login, string loginDomain) but only the object will be bound to POST data. As long as loginDomain comes from the querystring or route data this will work. Collecting POST values with FormDataCollection Another more dynamic approach to handle POST values is to collect POST data into a FormDataCollection. FormDataCollection is a very basic key/value collection (like FormCollection in MVC and Request.Form in ASP.NET in general) and then read the values out individually by querying each. [HttpPost] public HttpResponseMessage Authenticate(FormDataCollection form) { var username = form.Get("Username"); var password = form.Get("Password"); …} The downside to this approach is that it's not strongly typed, you have to handle type conversions on non-string parameters, and it gets a bit more complicated to test such as setup as you have to seed a FormDataCollection with data. On the other hand it's flexible and easy to use and especially with string parameters is easy to deal with. It's also dynamic, so if the client sends you a variety of combinations of values on which you make operating decisions, this is much easier to work with than a strongly typed object that would have to account for all possible values up front. The downside is that the code looks old school and isn't as self-documenting as a parameter list or object parameter would be. Nevertheless it's totally functionality and a viable choice for collecting POST values. What about [FromBody]? Web API also has a [FromBody] attribute that can be assigned to parameters. If you have multiple parameters on a Web API method signature you can use [FromBody] to specify which one will be parsed from the POST content. Unfortunately it's not terribly useful as it only returns content in raw format and requires a totally non-standard format ("=content") to specify your content. For more info in how FromBody works and several related issues to how POST data is mapped, you can check out Mike Stalls post: How WebAPI does Parameter Binding Not really sure where the Web API team thought [FromBody] would really be a good fit other than a down and dirty way to send a full string buffer. Extending Web API to make multiple POST Vars work? Don't think so Clearly there's no native support for multiple POST variables being mapped to parameters, which is a bit of a bummer. I know in my own work on one project my customer actually found this to be a real sticking point in their AJAX backend work, and we ended up not using Web API and using MVC JSON features instead. That's kind of sad because Web API is supposed to be the proper solution for AJAX backends. With all of ASP.NET Web API's extensibility you'd think there would be some way to build this functionality on our own, but after spending a bit of time digging and asking some of the experts from the team and Web API community I didn't hear anything that even suggests that this is possible. From what I could find I'd say it's not possible primarily because Web API's Routing engine does not account for the POST variable mapping. This means [HttpPost] methods with url encoded POST buffers are not mapped to the parameters of the endpoint, and so the routes would never even trigger a request that could be intercepted. Once the routing doesn't work there's not much that can be done. If somebody has an idea how this could be accomplished I would love to hear about it. Do we really need multi-value POST mapping? I think that that POST value mapping is a feature that one would expect of any API tool to have. If you look at common APIs out there like Flicker and Google Maps etc. they all work with POST data. POST data is very prominent much more so than JSON inputs and so supporting as many options that enable would seem to be crucial. All that aside, Web API does provide very nice features with Model Binding that allows you to capture many POST variables easily enough, and logistically this will let you build whatever you need with POST data of all shapes as long as you map objects. But having to have an object for every operation that receives a data input is going to take its toll in heavy AJAX applications, with a lot of types created that do nothing more than act as parameter containers. I also think that POST variable mapping is an expected behavior and Web APIs non-support will likely result in many, many questions like this one: How do I bind a simple POST value in ASP.NET WebAPI RC? with no clear answer to this question. I hope for V.next of WebAPI Microsoft will consider this a feature that's worth adding. Related Articles Passing multiple POST parameters to Web API Controller Methods Mike Stall's post: How Web API does Parameter Binding Where does ASP.NET Web API Fit?© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Parallelism in .NET – Part 4, Imperative Data Parallelism: Aggregation

    - by Reed
    In the article on simple data parallelism, I described how to perform an operation on an entire collection of elements in parallel.  Often, this is not adequate, as the parallel operation is going to be performing some form of aggregation. Simple examples of this might include taking the sum of the results of processing a function on each element in the collection, or finding the minimum of the collection given some criteria.  This can be done using the techniques described in simple data parallelism, however, special care needs to be taken into account to synchronize the shared data appropriately.  The Task Parallel Library has tools to assist in this synchronization. The main issue with aggregation when parallelizing a routine is that you need to handle synchronization of data.  Since multiple threads will need to write to a shared portion of data.  Suppose, for example, that we wanted to parallelize a simple loop that looked for the minimum value within a dataset: double min = double.MaxValue; foreach(var item in collection) { double value = item.PerformComputation(); min = System.Math.Min(min, value); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This seems like a good candidate for parallelization, but there is a problem here.  If we just wrap this into a call to Parallel.ForEach, we’ll introduce a critical race condition, and get the wrong answer.  Let’s look at what happens here: // Buggy code! Do not use! double min = double.MaxValue; Parallel.ForEach(collection, item => { double value = item.PerformComputation(); min = System.Math.Min(min, value); }); This code has a fatal flaw: min will be checked, then set, by multiple threads simultaneously.  Two threads may perform the check at the same time, and set the wrong value for min.  Say we get a value of 1 in thread 1, and a value of 2 in thread 2, and these two elements are the first two to run.  If both hit the min check line at the same time, both will determine that min should change, to 1 and 2 respectively.  If element 1 happens to set the variable first, then element 2 sets the min variable, we’ll detect a min value of 2 instead of 1.  This can lead to wrong answers. Unfortunately, fixing this, with the Parallel.ForEach call we’re using, would require adding locking.  We would need to rewrite this like: // Safe, but slow double min = double.MaxValue; // Make a "lock" object object syncObject = new object(); Parallel.ForEach(collection, item => { double value = item.PerformComputation(); lock(syncObject) min = System.Math.Min(min, value); }); This will potentially add a huge amount of overhead to our calculation.  Since we can potentially block while waiting on the lock for every single iteration, we will most likely slow this down to where it is actually quite a bit slower than our serial implementation.  The problem is the lock statement – any time you use lock(object), you’re almost assuring reduced performance in a parallel situation.  This leads to two observations I’ll make: When parallelizing a routine, try to avoid locks. That being said: Always add any and all required synchronization to avoid race conditions. These two observations tend to be opposing forces – we often need to synchronize our algorithms, but we also want to avoid the synchronization when possible.  Looking at our routine, there is no way to directly avoid this lock, since each element is potentially being run on a separate thread, and this lock is necessary in order for our routine to function correctly every time. However, this isn’t the only way to design this routine to implement this algorithm.  Realize that, although our collection may have thousands or even millions of elements, we have a limited number of Processing Elements (PE).  Processing Element is the standard term for a hardware element which can process and execute instructions.  This typically is a core in your processor, but many modern systems have multiple hardware execution threads per core.  The Task Parallel Library will not execute the work for each item in the collection as a separate work item. Instead, when Parallel.ForEach executes, it will partition the collection into larger “chunks” which get processed on different threads via the ThreadPool.  This helps reduce the threading overhead, and help the overall speed.  In general, the Parallel class will only use one thread per PE in the system. Given the fact that there are typically fewer threads than work items, we can rethink our algorithm design.  We can parallelize our algorithm more effectively by approaching it differently.  Because the basic aggregation we are doing here (Min) is communitive, we do not need to perform this in a given order.  We knew this to be true already – otherwise, we wouldn’t have been able to parallelize this routine in the first place.  With this in mind, we can treat each thread’s work independently, allowing each thread to serially process many elements with no locking, then, after all the threads are complete, “merge” together the results. This can be accomplished via a different set of overloads in the Parallel class: Parallel.ForEach<TSource,TLocal>.  The idea behind these overloads is to allow each thread to begin by initializing some local state (TLocal).  The thread will then process an entire set of items in the source collection, providing that state to the delegate which processes an individual item.  Finally, at the end, a separate delegate is run which allows you to handle merging that local state into your final results. To rewriting our routine using Parallel.ForEach<TSource,TLocal>, we need to provide three delegates instead of one.  The most basic version of this function is declared as: public static ParallelLoopResult ForEach<TSource, TLocal>( IEnumerable<TSource> source, Func<TLocal> localInit, Func<TSource, ParallelLoopState, TLocal, TLocal> body, Action<TLocal> localFinally ) The first delegate (the localInit argument) is defined as Func<TLocal>.  This delegate initializes our local state.  It should return some object we can use to track the results of a single thread’s operations. The second delegate (the body argument) is where our main processing occurs, although now, instead of being an Action<T>, we actually provide a Func<TSource, ParallelLoopState, TLocal, TLocal> delegate.  This delegate will receive three arguments: our original element from the collection (TSource), a ParallelLoopState which we can use for early termination, and the instance of our local state we created (TLocal).  It should do whatever processing you wish to occur per element, then return the value of the local state after processing is completed. The third delegate (the localFinally argument) is defined as Action<TLocal>.  This delegate is passed our local state after it’s been processed by all of the elements this thread will handle.  This is where you can merge your final results together.  This may require synchronization, but now, instead of synchronizing once per element (potentially millions of times), you’ll only have to synchronize once per thread, which is an ideal situation. Now that I’ve explained how this works, lets look at the code: // Safe, and fast! double min = double.MaxValue; // Make a "lock" object object syncObject = new object(); Parallel.ForEach( collection, // First, we provide a local state initialization delegate. () => double.MaxValue, // Next, we supply the body, which takes the original item, loop state, // and local state, and returns a new local state (item, loopState, localState) => { double value = item.PerformComputation(); return System.Math.Min(localState, value); }, // Finally, we provide an Action<TLocal>, to "merge" results together localState => { // This requires locking, but it's only once per used thread lock(syncObj) min = System.Math.Min(min, localState); } ); Although this is a bit more complicated than the previous version, it is now both thread-safe, and has minimal locking.  This same approach can be used by Parallel.For, although now, it’s Parallel.For<TLocal>.  When working with Parallel.For<TLocal>, you use the same triplet of delegates, with the same purpose and results. Also, many times, you can completely avoid locking by using a method of the Interlocked class to perform the final aggregation in an atomic operation.  The MSDN example demonstrating this same technique using Parallel.For uses the Interlocked class instead of a lock, since they are doing a sum operation on a long variable, which is possible via Interlocked.Add. By taking advantage of local state, we can use the Parallel class methods to parallelize algorithms such as aggregation, which, at first, may seem like poor candidates for parallelization.  Doing so requires careful consideration, and often requires a slight redesign of the algorithm, but the performance gains can be significant if handled in a way to avoid excessive synchronization.

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  • C#/.NET Little Wonders: The EventHandler and EventHandler&lt;TEventArgs&gt; delegates

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the last two weeks, we examined the Action family of delegates (and delegates in general), and the Func family of delegates and how they can be used to support generic, reusable algorithms and classes. So this week, we are going to look at a handy pair of delegates that can be used to eliminate the need for defining custom delegates when creating events: the EventHandler and EventHandler<TEventArgs> delegates. Events and delegates Before we begin, let’s quickly consider events in .NET.  According to the MSDN: An event in C# is a way for a class to provide notifications to clients of that class when some interesting thing happens to an object. So, basically, you can create an event in a type so that users of that type can subscribe to notifications of things of interest.  How is this different than some of the delegate programming that we talked about in the last two weeks?  Well, you can think of an event as a special access modifier on a delegate.  Some differences between the two are: Events are a special access case of delegates They behave much like delegates instances inside the type they are declared in, but outside of that type they can only be (un)subscribed to. Events can specify add/remove behavior explicitly If you want to do additional work when someone subscribes or unsubscribes to an event, you can specify the add and remove actions explicitly. Events have access modifiers, but these only specify the access level of those who can (un)subscribe A public event, for example, means anyone can (un)subscribe, but it does not mean that anyone can raise (invoke) the event directly.  Events can only be raised by the type that contains them In contrast, if a delegate is visible, it can be invoked outside of the object (not even in a sub-class!). Events tend to be for notifications only, and should be treated as optional Semantically speaking, events typically don’t perform work on the the class directly, but tend to just notify subscribers when something of note occurs. My basic rule-of-thumb is that if you are just wanting to notify any listeners (who may or may not care) that something has happened, use an event.  However, if you want the caller to provide some function to perform to direct the class about how it should perform work, make it a delegate. Declaring events using custom delegates To declare an event in a type, we simply use the event keyword and specify its delegate type.  For example, let’s say you wanted to create a new TimeOfDayTimer that triggers at a given time of the day (as opposed to on an interval).  We could write something like this: 1: public delegate void TimeOfDayHandler(object source, ElapsedEventArgs e); 2:  3: // A timer that will fire at time of day each day. 4: public class TimeOfDayTimer : IDisposable 5: { 6: // Event that is triggered at time of day. 7: public event TimeOfDayHandler Elapsed; 8:  9: // ... 10: } The first thing to note is that the event is a delegate type, which tells us what types of methods may subscribe to it.  The second thing to note is the signature of the event handler delegate, according to the MSDN: The standard signature of an event handler delegate defines a method that does not return a value, whose first parameter is of type Object and refers to the instance that raises the event, and whose second parameter is derived from type EventArgs and holds the event data. If the event does not generate event data, the second parameter is simply an instance of EventArgs. Otherwise, the second parameter is a custom type derived from EventArgs and supplies any fields or properties needed to hold the event data. So, in a nutshell, the event handler delegates should return void and take two parameters: An object reference to the object that raised the event. An EventArgs (or a subclass of EventArgs) reference to event specific information. Even if your event has no additional information to provide, you are still expected to provide an EventArgs instance.  In this case, feel free to pass the EventArgs.Empty singleton instead of creating new instances of EventArgs (to avoid generating unneeded memory garbage). The EventHandler delegate Because many events have no additional information to pass, and thus do not require custom EventArgs, the signature of the delegates for subscribing to these events is typically: 1: // always takes an object and an EventArgs reference 2: public delegate void EventHandler(object sender, EventArgs e) It would be insane to recreate this delegate for every class that had a basic event with no additional event data, so there already exists a delegate for you called EventHandler that has this very definition!  Feel free to use it to define any events which supply no additional event information: 1: public class Cache 2: { 3: // event that is raised whenever the cache performs a cleanup 4: public event EventHandler OnCleanup; 5:  6: // ... 7: } This will handle any event with the standard EventArgs (no additional information).  But what of events that do need to supply additional information?  Does that mean we’re out of luck for subclasses of EventArgs?  That’s where the generic for of EventHandler comes into play… The generic EventHandler<TEventArgs> delegate Starting with the introduction of generics in .NET 2.0, we have a generic delegate called EventHandler<TEventArgs>.  Its signature is as follows: 1: public delegate void EventHandler<TEventArgs>(object sender, TEventArgs e) 2: where TEventArgs : EventArgs This is similar to EventHandler except it has been made generic to support the more general case.  Thus, it will work for any delegate where the first argument is an object (the sender) and the second argument is a class derived from EventArgs (the event data). For example, let’s say we wanted to create a message receiver, and we wanted it to have a few events such as OnConnected that will tell us when a connection is established (probably with no additional information) and OnMessageReceived that will tell us when a new message arrives (probably with a string for the new message text). So for OnMessageReceived, our MessageReceivedEventArgs might look like this: 1: public sealed class MessageReceivedEventArgs : EventArgs 2: { 3: public string Message { get; set; } 4: } And since OnConnected needs no event argument type defined, our class might look something like this: 1: public class MessageReceiver 2: { 3: // event that is called when the receiver connects with sender 4: public event EventHandler OnConnected; 5:  6: // event that is called when a new message is received. 7: public event EventHandler<MessageReceivedEventArgs> OnMessageReceived; 8:  9: // ... 10: } Notice, nowhere did we have to define a delegate to fit our event definition, the EventHandler and generic EventHandler<TEventArgs> delegates fit almost anything we’d need to do with events. Sidebar: Thread-safety and raising an event When the time comes to raise an event, we should always check to make sure there are subscribers, and then only raise the event if anyone is subscribed.  This is important because if no one is subscribed to the event, then the instance will be null and we will get a NullReferenceException if we attempt to raise the event. 1: // This protects against NullReferenceException... or does it? 2: if (OnMessageReceived != null) 3: { 4: OnMessageReceived(this, new MessageReceivedEventArgs(aMessage)); 5: } The above code seems to handle the null reference if no one is subscribed, but there’s a problem if this is being used in multi-threaded environments.  For example, assume we have thread A which is about to raise the event, and it checks and clears the null check and is about to raise the event.  However, before it can do that thread B unsubscribes to the event, which sets the delegate to null.  Now, when thread A attempts to raise the event, this causes the NullReferenceException that we were hoping to avoid! To counter this, the simplest best-practice method is to copy the event (just a multicast delegate) to a temporary local variable just before we raise it.  Since we are inside the class where this event is being raised, we can copy it to a local variable like this, and it will protect us from multi-threading since multicast delegates are immutable and assignments are atomic: 1: // always make copy of the event multi-cast delegate before checking 2: // for null to avoid race-condition between the null-check and raising it. 3: var handler = OnMessageReceived; 4: 5: if (handler != null) 6: { 7: handler(this, new MessageReceivedEventArgs(aMessage)); 8: } The very slight trade-off is that it’s possible a class may get an event after it unsubscribes in a multi-threaded environment, but this is a small risk and classes should be prepared for this possibility anyway.  For a more detailed discussion on this, check out this excellent Eric Lippert blog post on Events and Races. Summary Generic delegates give us a lot of power to make generic algorithms and classes, and the EventHandler delegate family gives us the flexibility to create events easily, without needing to redefine delegates over and over.  Use them whenever you need to define events with or without specialized EventArgs.   Tweet Technorati Tags: .NET, C#, CSharp, Little Wonders, Generics, Delegates, EventHandler

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  • Book Review - Programming Windows Azure by Siriram Krishnan

    - by BuckWoody
    As part of my professional development, I’ve created a list of books to read throughout the year, starting in June of 2011. This a review of the first one, called Programming Windows Azure by Siriram Krishnan. You can find my entire list of books I’m reading for my career here: http://blogs.msdn.com/b/buckwoody/archive/2011/06/07/head-in-the-clouds-eyes-on-the-books.aspx  Why I Chose This Book: As part of my learning style, I try to read multiple books about a single subject. I’ve found that at least 3 books are necessary to get the right amount of information to me. This is a “technical” work, meaning that it deals with technology and not business, writing or other facets of my career. I’ll have a mix of all of those as I read along. I chose this work in addition to others I’ve read since it covers everything from an introduction to more advanced topics in a single book. It also has some practical examples of actually working with the product, particularly on storage. Although it’s dated, many examples normally translate. I also saw that it had pretty good reviews. What I learned: I learned a great deal about storage, and many useful code snippets. I do think that there could have been more of a focus on the application fabric - but of course that wasn’t as mature a feature when this book was written. I learned some great architecture examples, and in one section I learned more about encryption. In that example, however, I would rather have seen the examples go the other way - the book focused on moving data from on-premise to Azure storage in an encrypted fashion. Using the Application Fabric I would rather see sensitive data left in a hybrid fashion on premise, and connect to for the Azure application. Even so, the examples were very useful. If you’re looking for a good “starter” Azure book, this is a good choice. I also recommend the last chapter as a quick read for a DBA, or Database Administrator. It’s not very long, but useful. Note that the limits described are incorrect - which is one of the dangers of reading a book about any cloud offering. The services offered are updated so quickly that the information is in constant danger of being “stale”. Even so, I found this a useful book, which I believe will help me work with Azure better. Raw Notes: I take notes as I read, calling that process “reading with a pencil”. I find that when I do that I pay attention better, and record some things that I need to know later. I’ll take these notes, categorize them into a OneNote notebook that I synchronize in my Live.com account, and that way I can search them from anywhere. I can even read them on the web, since the Live.com has a OneNote program built in. Note that these are the raw notes, so they might not make a lot of sense out of context - I include them here so you can watch my though process. Programming Windows Azure by Siriram Krishnan: Learning about how to select applications suitable for Distributed Technology. Application Fabric gets the least attention; probably because it was newer at the time. Very clear (Chapter One) Good foundation Background and history, but not too much I normally arrange my descriptions differently, starting with the use-cases and moving to physicality, but this difference helps me. Interesting that I am reading this using Safari Books Online, which uses many of these concepts. Taught me some new aspects of a Hypervisor – very low-level information about the Azure Fabric (not to be confused with the Application Fabric feature) (Chapter Two) Good detail of what is included in the SDK. Even more is available now. CS = Cloud Service (Chapter 3) Place Storage info in the configuration file, since it can be streamed in-line with a running app. Ditto for logging, and keep separated configs for staging and testing. Easy-switch in and switch out.  (Chapter 4) There are two Runtime API’s, one of external and one for internal. Realizing how powerful this paradigm really is. Some places seem light, and to drop off but perhaps that’s best. Managing API is not charged, which is nice. I don’t often think about the price, until it comes to an actual deployment (Chapter 5) Csmanage is something I want to dig into deeper. API requires package moves to Blob storage first, so it needs a URL. Csmanage equivalent can be written in Unix scripting using openssl. Upgrades are possible, and you use the upgradeDomainCount attribute in the Service-Definition.csdef file  Always use a low-privileged account to test on the dev fabric, since Windows Azure runs in partial trust. Full trust is available, but can be dangerous and must be well-thought out. (Chapter 6) Learned how to run full CMD commands in a web window – not that you would ever do that, but it was an interesting view into those links. This leads to a discussion on hosting other runtimes (such as Java or PHP) in Windows Azure. I got an expanded view on this process, although this is where the book shows its age a little. Books can be a problem for Cloud Computing for this reason – things just change too quickly. Windows Azure storage is not eventually consistent – it is instantly consistent with multi-phase commit. Plumbing for this is internal, not required to code that. (Chapter 7) REST API makes the service interoperable, hybrid, and consistent across code architectures. Nicely done. Use affinity groups to keep data and code together. Side note: e-book readers need a common “notes” feature. There’s a decent quick description of REST in this chapter. Learned about CloudDrive code – PowerShell sample that mounts Blob storage as a local provider. Works against Dev fabric by default, can be switched to Account. Good treatment in the storage chapters on the differences between using Dev storage and Azure storage. These can be mitigated. No, blobs are not of any size or number. Not a good statement (Chapter 8) Blob storage is probably Azure’s closest play to Infrastructure as a Service (Iaas). Blob change operations must be authenticated, even when public. Chapters on storage are pretty in-depth. Queue Messages are base-64 encoded (Chapter 9) The visibility timeout ensures processing of message in a disconnected system. Order is not guaranteed for a message, so if you need that set an increasing number in the queue mechanism. While Queues are accessible via REST, they are not public and are secured by default. Interesting – the header for a queue request includes an estimated count. This can be useful to create more worker roles in a dynamic system. Each Entity (row) in the Azure Table service is atomic – all or nothing. (Chapter 10) An entity can have up to 255 Properties  Use “ID” for the class to indicate the key value, or use the [DataServiceKey] Attribute.  LINQ makes working with the Azure Table Service much easier, although Interop is certainly possible. Good description on the process of selecting the Partition and Row Key.  When checking for continuation tokens for pagination, include logic that falls out of the check in case you are at the last page.  On deleting a storage object, it is instantly unavailable, however a background process is dispatched to perform the physical deletion. So if you want to re-create a storage object with the same name, add retry logic into the code. Interesting approach to deleting an index entity without having to read it first – create a local entity with the same keys and apply it to the Azure system regardless of change-state.  Although the “Indexes” description is a little vague, it’s interesting to see a Folding and Stemming discussion a-la the Porter Stemming Algorithm. (Chapter 11)  Presents a better discussion of indexes (at least inverted indexes) later in the chapter. Great treatment for DBA’s in Chapter 11. We need to work on getting secondary indexes in Table storage. There is a limited form of transactions called “Entity Group Transactions” that, although they have conditions, makes a transactional system more possible. Concurrency also becomes an issue, but is handled well if you’re using Data Services in .NET. It watches the Etag and allows you to take action appropriately. I do not recommend using Azure as a location for secure backups. In fact, I would rather have seen the examples in (Chapter 12) go the other way, showing how data could be brought back to a local store as a DR or HA strategy. Good information on cryptography and so on even so. Chapter seems out of place, and should be combined with the Blob chapter.  (Chapter 13) on SQL Azure is dated, although the base concepts are OK.  Nice example of simple ADO.NET access to a SQL Azure (or any SQL Server Really) database.  

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  • Commit in SQL

    - by PRajkumar
    SQL Transaction Control Language Commands (TCL)                                           (COMMIT) Commit Transaction As a SQL language we use transaction control language very frequently. Committing a transaction means making permanent the changes performed by the SQL statements within the transaction. A transaction is a sequence of SQL statements that Oracle Database treats as a single unit. This statement also erases all save points in the transaction and releases transaction locks. Oracle Database issues an implicit COMMIT before and after any data definition language (DDL) statement. Oracle recommends that you explicitly end every transaction in your application programs with a COMMIT or ROLLBACK statement, including the last transaction, before disconnecting from Oracle Database. If you do not explicitly commit the transaction and the program terminates abnormally, then the last uncommitted transaction is automatically rolled back.   Until you commit a transaction: ·         You can see any changes you have made during the transaction by querying the modified tables, but other users cannot see the changes. After you commit the transaction, the changes are visible to other users' statements that execute after the commit ·         You can roll back (undo) any changes made during the transaction with the ROLLBACK statement   Note: Most of the people think that when we type commit data or changes of what you have made has been written to data files, but this is wrong when you type commit it means that you are saying that your job has been completed and respective verification will be done by oracle engine that means it checks whether your transaction achieved consistency when it finds ok it sends a commit message to the user from log buffer but not from data buffer, so after writing data in log buffer it insists data buffer to write data in to data files, this is how it works.   Before a transaction that modifies data is committed, the following has occurred: ·         Oracle has generated undo information. The undo information contains the old data values changed by the SQL statements of the transaction ·         Oracle has generated redo log entries in the redo log buffer of the System Global Area (SGA). The redo log record contains the change to the data block and the change to the rollback block. These changes may go to disk before a transaction is committed ·         The changes have been made to the database buffers of the SGA. These changes may go to disk before a transaction is committed   Note:   The data changes for a committed transaction, stored in the database buffers of the SGA, are not necessarily written immediately to the data files by the database writer (DBWn) background process. This writing takes place when it is most efficient for the database to do so. It can happen before the transaction commits or, alternatively, it can happen some times after the transaction commits.   When a transaction is committed, the following occurs: 1.      The internal transaction table for the associated undo table space records that the transaction has committed, and the corresponding unique system change number (SCN) of the transaction is assigned and recorded in the table 2.      The log writer process (LGWR) writes redo log entries in the SGA's redo log buffers to the redo log file. It also writes the transaction's SCN to the redo log file. This atomic event constitutes the commit of the transaction 3.      Oracle releases locks held on rows and tables 4.      Oracle marks the transaction complete   Note:   The default behavior is for LGWR to write redo to the online redo log files synchronously and for transactions to wait for the redo to go to disk before returning a commit to the user. However, for lower transaction commit latency application developers can specify that redo be written asynchronously and that transaction do not need to wait for the redo to be on disk.   The syntax of Commit Statement is   COMMIT [WORK] [COMMENT ‘your comment’]; ·         WORK is optional. The WORK keyword is supported for compliance with standard SQL. The statements COMMIT and COMMIT WORK are equivalent. Examples Committing an Insert INSERT INTO table_name VALUES (val1, val2); COMMIT WORK; ·         COMMENT Comment is also optional. This clause is supported for backward compatibility. Oracle recommends that you used named transactions instead of commit comments. Specify a comment to be associated with the current transaction. The 'text' is a quoted literal of up to 255 bytes that Oracle Database stores in the data dictionary view DBA_2PC_PENDING along with the transaction ID if a distributed transaction becomes in doubt. This comment can help you diagnose the failure of a distributed transaction. Examples The following statement commits the current transaction and associates a comment with it: COMMIT     COMMENT 'In-doubt transaction Code 36, Call (415) 555-2637'; ·         WRITE Clause Use this clause to specify the priority with which the redo information generated by the commit operation is written to the redo log. This clause can improve performance by reducing latency, thus eliminating the wait for an I/O to the redo log. Use this clause to improve response time in environments with stringent response time requirements where the following conditions apply: The volume of update transactions is large, requiring that the redo log be written to disk frequently. The application can tolerate the loss of an asynchronously committed transaction. The latency contributed by waiting for the redo log write to occur contributes significantly to overall response time. You can specify the WAIT | NOWAIT and IMMEDIATE | BATCH clauses in any order. Examples To commit the same insert operation and instruct the database to buffer the change to the redo log, without initiating disk I/O, use the following COMMIT statement: COMMIT WRITE BATCH; Note: If you omit this clause, then the behavior of the commit operation is controlled by the COMMIT_WRITE initialization parameter, if it has been set. The default value of the parameter is the same as the default for this clause. Therefore, if the parameter has not been set and you omit this clause, then commit records are written to disk before control is returned to the user. WAIT | NOWAIT Use these clauses to specify when control returns to the user. The WAIT parameter ensures that the commit will return only after the corresponding redo is persistent in the online redo log. Whether in BATCH or IMMEDIATE mode, when the client receives a successful return from this COMMIT statement, the transaction has been committed to durable media. A crash occurring after a successful write to the log can prevent the success message from returning to the client. In this case the client cannot tell whether or not the transaction committed. The NOWAIT parameter causes the commit to return to the client whether or not the write to the redo log has completed. This behavior can increase transaction throughput. With the WAIT parameter, if the commit message is received, then you can be sure that no data has been lost. Caution: With NOWAIT, a crash occurring after the commit message is received, but before the redo log record(s) are written, can falsely indicate to a transaction that its changes are persistent. If you omit this clause, then the transaction commits with the WAIT behavior. IMMEDIATE | BATCH Use these clauses to specify when the redo is written to the log. The IMMEDIATE parameter causes the log writer process (LGWR) to write the transaction's redo information to the log. This operation option forces a disk I/O, so it can reduce transaction throughput. The BATCH parameter causes the redo to be buffered to the redo log, along with other concurrently executing transactions. When sufficient redo information is collected, a disk write of the redo log is initiated. This behavior is called "group commit", as redo for multiple transactions is written to the log in a single I/O operation. If you omit this clause, then the transaction commits with the IMMEDIATE behavior. ·         FORCE Clause Use this clause to manually commit an in-doubt distributed transaction or a corrupt transaction. ·         In a distributed database system, the FORCE string [, integer] clause lets you manually commit an in-doubt distributed transaction. The transaction is identified by the 'string' containing its local or global transaction ID. To find the IDs of such transactions, query the data dictionary view DBA_2PC_PENDING. You can use integer to specifically assign the transaction a system change number (SCN). If you omit integer, then the transaction is committed using the current SCN. ·         The FORCE CORRUPT_XID 'string' clause lets you manually commit a single corrupt transaction, where string is the ID of the corrupt transaction. Query the V$CORRUPT_XID_LIST data dictionary view to find the transaction IDs of corrupt transactions. You must have DBA privileges to view the V$CORRUPT_XID_LIST and to specify this clause. ·         Specify FORCE CORRUPT_XID_ALL to manually commit all corrupt transactions. You must have DBA privileges to specify this clause. Examples Forcing an in doubt transaction. Example The following statement manually commits a hypothetical in-doubt distributed transaction. Query the V$CORRUPT_XID_LIST data dictionary view to find the transaction IDs of corrupt transactions. You must have DBA privileges to view the V$CORRUPT_XID_LIST and to issue this statement. COMMIT FORCE '22.57.53';

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  • ANTS Memory Profiler 7.0 Review

    - by Michael B. McLaughlin
    (This is my first review as a part of the GeeksWithBlogs.net Influencers program. It’s a program in which I (and the others who have been selected for it) get the opportunity to check out new products and services and write reviews about them. We don’t get paid for this, but we do generally get to keep a copy of the software or retain an account for some period of time on the service that we review. In this case I received a copy of Red Gate Software’s ANTS Memory Profiler 7.0, which was released in January. I don’t have any upgrade rights nor is my review guided, restrained, influenced, or otherwise controlled by Red Gate or anyone else. But I do get to keep the software license. I will always be clear about what I received whenever I do a review – I leave it up to you to decide whether you believe I can be objective. I believe I can be. If I used something and really didn’t like it, keeping a copy of it wouldn’t be worth anything to me. In that case though, I would simply uninstall/deactivate/whatever the software or service and tell the company what I didn’t like about it so they could (hopefully) make it better in the future. I don’t think it’d be polite to write up a terrible review, nor do I think it would be a particularly good use of my time. There are people who get paid for a living to review things, so I leave it to them to tell you what they think is bad and why. I’ll only spend my time telling you about things I think are good.) Overview of Common .NET Memory Problems When coming to land of managed memory from the wilds of unmanaged code, it’s easy to say to one’s self, “Wow! Now I never have to worry about memory problems again!” But this simply isn’t true. Managed code environments, such as .NET, make many, many things easier. You will never have to worry about memory corruption due to a bad pointer, for example (unless you’re working with unsafe code, of course). But managed code has its own set of memory concerns. For example, failing to unsubscribe from events when you are done with them leaves the publisher of an event with a reference to the subscriber. If you eliminate all your own references to the subscriber, then that memory is effectively lost since the GC won’t delete it because of the publishing object’s reference. When the publishing object itself becomes subject to garbage collection then you’ll get that memory back finally, but that could take a very long time depending of the life of the publisher. Another common source of resource leaks is failing to properly release unmanaged resources. When writing a class that contains members that hold unmanaged resources (e.g. any of the Stream-derived classes, IsolatedStorageFile, most classes ending in “Reader” or “Writer”), you should always implement IDisposable, making sure to use a properly written Dispose method. And when you are using an instance of a class that implements IDisposable, you should always make sure to use a 'using' statement in order to ensure that the object’s unmanaged resources are disposed of properly. (A ‘using’ statement is a nicer, cleaner looking, and easier to use version of a try-finally block. The compiler actually translates it as though it were a try-finally block. Note that Code Analysis warning 2202 (CA2202) will often be triggered by nested using blocks. A properly written dispose method ensures that it only runs once such that calling dispose multiple times should not be a problem. Nonetheless, CA2202 exists and if you want to avoid triggering it then you should write your code such that only the innermost IDisposable object uses a ‘using’ statement, with any outer code making use of appropriate try-finally blocks instead). Then, of course, there are situations where you are operating in a memory-constrained environment or else you want to limit or even eliminate allocations within a certain part of your program (e.g. within the main game loop of an XNA game) in order to avoid having the GC run. On the Xbox 360 and Windows Phone 7, for example, for every 1 MB of heap allocations you make, the GC runs; the added time of a GC collection can cause a game to drop frames or run slowly thereby making it look bad. Eliminating allocations (or else minimizing them and calling an explicit Collect at an appropriate time) is a common way of avoiding this (the other way is to simplify your heap so that the GC’s latency is low enough not to cause performance issues). ANTS Memory Profiler 7.0 When the opportunity to review Red Gate’s recently released ANTS Memory Profiler 7.0 arose, I jumped at it. In order to review it, I was given a free copy (which does not include upgrade rights for future versions) which I am allowed to keep. For those of you who are familiar with ANTS Memory Profiler, you can find a list of new features and enhancements here. If you are an experienced .NET developer who is familiar with .NET memory management issues, ANTS Memory Profiler is great. More importantly still, if you are new to .NET development or you have no experience or limited experience with memory profiling, ANTS Memory Profiler is awesome. From the very beginning, it guides you through the process of memory profiling. If you’re experienced and just want dive in however, it doesn’t get in your way. The help items GAHSFLASHDAJLDJA are well designed and located right next to the UI controls so that they are easy to find without being intrusive. When you first launch it, it presents you with a “Getting Started” screen that contains links to “Memory profiling video tutorials”, “Strategies for memory profiling”, and the “ANTS Memory Profiler forum”. I’m normally the kind of person who looks at a screen like that only to find the “Don’t show this again” checkbox. Since I was doing a review, though, I decided I should examine them. I was pleasantly surprised. The overview video clocks in at three minutes and fifty seconds. It begins by showing you how to get started profiling an application. It explains that profiling is done by taking memory snapshots periodically while your program is running and then comparing them. ANTS Memory Profiler (I’m just going to call it “ANTS MP” from here) analyzes these snapshots in the background while your application is running. It briefly mentions a new feature in Version 7, a new API that give you the ability to trigger snapshots from within your application’s source code (more about this below). You can also, and this is the more common way you would do it, take a memory snapshot at any time from within the ANTS MP window by clicking the “Take Memory Snapshot” button in the upper right corner. The overview video goes on to demonstrate a basic profiling session on an application that pulls information from a database and displays it. It shows how to switch which snapshots you are comparing, explains the different sections of the Summary view and what they are showing, and proceeds to show you how to investigate memory problems using the “Instance Categorizer” to track the path from an object (or set of objects) to the GC’s root in order to find what things along the path are holding a reference to it/them. For a set of objects, you can then click on it and get the “Instance List” view. This displays all of the individual objects (including their individual sizes, values, etc.) of that type which share the same path to the GC root. You can then click on one of the objects to generate an “Instance Retention Graph” view. This lets you track directly up to see the reference chain for that individual object. In the overview video, it turned out that there was an event handler which was holding on to a reference, thereby keeping a large number of strings that should have been freed in memory. Lastly the video shows the “Class List” view, which lets you dig in deeply to find problems that might not have been clear when following the previous workflow. Once you have at least one memory snapshot you can begin analyzing. The main interface is in the “Analysis” tab. You can also switch to the “Session Overview” tab, which gives you several bar charts highlighting basic memory data about the snapshots you’ve taken. If you hover over the individual bars (and the individual colors in bars that have more than one), you will see a detailed text description of what the bar is representing visually. The Session Overview is good for a quick summary of memory usage and information about the different heaps. You are going to spend most of your time in the Analysis tab, but it’s good to remember that the Session Overview is there to give you some quick feedback on basic memory usage stats. As described above in the summary of the overview video, there is a certain natural workflow to the Analysis tab. You’ll spin up your application and take some snapshots at various times such as before and after clicking a button to open a window or before and after closing a window. Taking these snapshots lets you examine what is happening with memory. You would normally expect that a lot of memory would be freed up when closing a window or exiting a document. By taking snapshots before and after performing an action like that you can see whether or not the memory is really being freed. If you already know an area that’s giving you trouble, you can run your application just like normal until just before getting to that part and then you can take a few strategic snapshots that should help you pin down the problem. Something the overview didn’t go into is how to use the “Filters” section at the bottom of ANTS MP together with the Class List view in order to narrow things down. The video tutorials page has a nice 3 minute intro video called “How to use the filters”. It’s a nice introduction and covers some of the basics. I’m going to cover a bit more because I think they’re a really neat, really helpful feature. Large programs can bring up thousands of classes. Even simple programs can instantiate far more classes than you might realize. In a basic .NET 4 WPF application for example (and when I say basic, I mean just MainWindow.xaml with a button added to it), the unfiltered Class List view will have in excess of 1000 classes (my simple test app had anywhere from 1066 to 1148 classes depending on which snapshot I was using as the “Current” snapshot). This is amazing in some ways as it shows you how in stark detail just how immensely powerful the WPF framework is. But hunting through 1100 classes isn’t productive, no matter how cool it is that there are that many classes instantiated and doing all sorts of awesome things. Let’s say you wanted to examine just the classes your application contains source code for (in my simple example, that would be the MainWindow and App). Under “Basic Filters”, click on “Classes with source” under “Show only…”. Voilà. Down from 1070 classes in the snapshot I was using as “Current” to 2 classes. If you then click on a class’s name, it will show you (to the right of the class name) two little icon buttons. Hover over them and you will see that you can click one to view the Instance Categorizer for the class and another to view the Instance List for the class. You can also show classes based on which heap they live on. If you chose both a Baseline snapshot and a Current snapshot then you can use the “Comparing snapshots” filters to show only: “New objects”; “Surviving objects”; “Survivors in growing classes”; or “Zombie objects” (if you aren’t sure what one of these means, you can click the helpful “?” in a green circle icon to bring up a popup that explains them and provides context). Remember that your selection(s) under the “Show only…” heading will still apply, so you should update those selections to make sure you are seeing the view you want. There are also links under the “What is my memory problem?” heading that can help you diagnose the problems you are seeing including one for “I don’t know which kind I have” for situations where you know generally that your application has some problems but aren’t sure what the behavior you have been seeing (OutOfMemoryExceptions, continually growing memory usage, larger memory use than expected at certain points in the program). The Basic Filters are not the only filters there are. “Filter by Object Type” gives you the ability to filter by: “Objects that are disposable”; “Objects that are/are not disposed”; “Objects that are/are not GC roots” (GC roots are things like static variables); and “Objects that implement _______”. “Objects that implement” is particularly neat. Once you check the box, you can then add one or more classes and interfaces that an object must implement in order to survive the filtering. Lastly there is “Filter by Reference”, which gives you the option to pare down the list based on whether an object is “Kept in memory exclusively by” a particular item, a class/interface, or a namespace; whether an object is “Referenced by” one or more of those choices; and whether an object is “Never referenced by” one or more of those choices. Remember that filtering is cumulative, so anything you had set in one of the filter sections still remains in effect unless and until you go back and change it. There’s quite a bit more to ANTS MP – it’s a very full featured product – but I think I touched on all of the most significant pieces. You can use it to debug: a .NET executable; an ASP.NET web application (running on IIS); an ASP.NET web application (running on Visual Studio’s built-in web development server); a Silverlight 4 browser application; a Windows service; a COM+ server; and even something called an XBAP (local XAML browser application). You can also attach to a .NET 4 process to profile an application that’s already running. The startup screen also has a large number of “Charting Options” that let you adjust which statistics ANTS MP should collect. The default selection is a good, minimal set. It’s worth your time to browse through the charting options to examine other statistics that may also help you diagnose a particular problem. The more statistics ANTS MP collects, the longer it will take to collect statistics. So just turning everything on is probably a bad idea. But the option to selectively add in additional performance counters from the extensive list could be a very helpful thing for your memory profiling as it lets you see additional data that might provide clues about a particular problem that has been bothering you. ANTS MP integrates very nicely with all versions of Visual Studio that support plugins (i.e. all of the non-Express versions). Just note that if you choose “Profile Memory” from the “ANTS” menu that it will launch profiling for whichever project you have set as the Startup project. One quick tip from my experience so far using ANTS MP: if you want to properly understand your memory usage in an application you’ve written, first create an “empty” version of the type of project you are going to profile (a WPF application, an XNA game, etc.) and do a quick profiling session on that so that you know the baseline memory usage of the framework itself. By “empty” I mean just create a new project of that type in Visual Studio then compile it and run it with profiling – don’t do anything special or add in anything (except perhaps for any external libraries you’re planning to use). The first thing I tried ANTS MP out on was a demo XNA project of an editor that I’ve been working on for quite some time that involves a custom extension to XNA’s content pipeline. The first time I ran it and saw the unmanaged memory usage I was convinced I had some horrible bug that was creating extra copies of texture data (the demo project didn’t have a lot of texture data so when I saw a lot of unmanaged memory I instantly figured I was doing something wrong). Then I thought to run an empty project through and when I saw that the amount of unmanaged memory was virtually identical, it dawned on me that the CLR itself sits in unmanaged memory and that (thankfully) there was nothing wrong with my code! Quite a relief. Earlier, when discussing the overview video, I mentioned the API that lets you take snapshots from within your application. I gave it a quick trial and it’s very easy to integrate and make use of and is a really nice addition (especially for projects where you want to know what, if any, allocations there are in a specific, complicated section of code). The only concern I had was that if I hadn’t watched the overview video I might never have known it existed. Even then it took me five minutes of hunting around Red Gate’s website before I found the “Taking snapshots from your code" article that explains what DLL you need to add as a reference and what method of what class you should call in order to take an automatic snapshot (including the helpful warning to wrap it in a try-catch block since, under certain circumstances, it can raise an exception, such as trying to call it more than 5 times in 30 seconds. The difficulty in discovering and then finding information about the automatic snapshots API was one thing I thought could use improvement. Another thing I think would make it even better would be local copies of the webpages it links to. Although I’m generally always connected to the internet, I imagine there are more than a few developers who aren’t or who are behind very restrictive firewalls. For them (and for me, too, if my internet connection happens to be down), it would be nice to have those documents installed locally or to have the option to download an additional “documentation” package that would add local copies. Another thing that I wish could be easier to manage is the Filters area. Finding and setting individual filters is very easy as is understanding what those filter do. And breaking it up into three sections (basic, by object, and by reference) makes sense. But I could easily see myself running a long profiling session and forgetting that I had set some filter a long while earlier in a different filter section and then spending quite a bit of time trying to figure out why some problem that was clearly visible in the data wasn’t showing up in, e.g. the instance list before remembering to check all the filters for that one setting that was only culling a few things from view. Some sort of indicator icon next to the filter section names that appears you have at least one filter set in that area would be a nice visual clue to remind me that “oh yeah, I told it to only show objects on the Gen 2 heap! That’s why I’m not seeing those instances of the SuperMagic class!” Something that would be nice (but that Red Gate cannot really do anything about) would be if this could be used in Windows Phone 7 development. If Microsoft and Red Gate could work together to make this happen (even if just on the WP7 emulator), that would be amazing. Especially given the memory constraints that apps and games running on mobile devices need to work within, a good memory profiler would be a phenomenally helpful tool. If anyone at Microsoft reads this, it’d be really great if you could make something like that happen. Perhaps even a (subsidized) custom version just for WP7 development. (For XNA games, of course, you can create a Windows version of the game and use ANTS MP on the Windows version in order to get a better picture of your memory situation. For Silverlight on WP7, though, there’s quite a bit of educated guess work and WeakReference creation followed by forced collections in order to find the source of a memory problem.) The only other thing I found myself wanting was a “Back” button. Between my Windows Phone 7, Zune, and other things, I’ve grown very used to having a “back stack” that lets me just navigate back to where I came from. The ANTS MP interface is surprisingly easy to use given how much it lets you do, and once you start using it for any amount of time, you learn all of the different areas such that you know where to go. And it does remember the state of the areas you were previously in, of course. So if you go to, e.g., the Instance Retention Graph from the Class List and then return back to the Class List, it will remember which class you had selected and all that other state information. Still, a “Back” button would be a welcome addition to a future release. Bottom Line ANTS Memory Profiler is not an inexpensive tool. But my time is valuable. I can easily see ANTS MP saving me enough time tracking down memory problems to justify it on a cost basis. More importantly to me, knowing what is happening memory-wise in my programs and having the confidence that my code doesn’t have any hidden time bombs in it that will cause it to OOM if I leave it running for longer than I do when I spin it up real quickly for debugging or just to see how a new feature looks and feels is a good feeling. It’s a feeling that I like having and want to continue to have. I got the current version for free in order to review it. Having done so, I’ve now added it to my must-have tools and will gladly lay out the money for the next version when it comes out. It has a 14 day free trial, so if you aren’t sure if it’s right for you or if you think it seems interesting but aren’t really sure if it’s worth shelling out the money for it, give it a try.

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  • Top 5 Developer Enabling Nuggets in MySQL 5.6

    - by Rob Young
    MySQL 5.6 is truly a better MySQL and reflects Oracle's commitment to the evolution of the most popular and widelyused open source database on the planet.  The feature-complete 5.6 release candidate was announced at MySQL Connect in late September and the production-ready, generally available ("GA") product should be available in early 2013.  While the message around 5.6 has been focused mainly on mass appeal, advanced topics like performance/scale, high availability, and self-healing replication clusters, MySQL 5.6 also provides many developer-friendly nuggets that are designed to enable those who are building the next generation of web-based and embedded applications and services. Boiling down the 5.6 feature set into a smaller set, of simple, easy to use goodies designed with developer agility in mind, these things deserve a quick look:Subquery Optimizations Using semi-JOINs and late materialization, the MySQL 5.6 Optimizer delivers greatly improved subquery performance. Specifically, the optimizer is now more efficient in handling subqueries in the FROM clause; materialization of subqueries in the FROM clause is now postponed until their contents are needed during execution. Additionally, the optimizer may add an index to derived tables during execution to speed up row retrieval. Internal tests run using the DBT-3 benchmark Query #13, shown below, demonstrate an order of magnitude improvement in execution times (from days to seconds) over previous versions. select c_name, c_custkey, o_orderkey, o_orderdate, o_totalprice, sum(l_quantity)from customer, orders, lineitemwhere o_orderkey in (                select l_orderkey                from lineitem                group by l_orderkey                having sum(l_quantity) > 313  )  and c_custkey = o_custkey  and o_orderkey = l_orderkeygroup by c_name, c_custkey, o_orderkey, o_orderdate, o_totalpriceorder by o_totalprice desc, o_orderdateLIMIT 100;What does this mean for developers?  For starters, simplified subqueries can now be coded instead of complex joins for cross table lookups: SELECT title FROM film WHERE film_id IN (SELECT film_id FROM film_actor GROUP BY film_id HAVING count(*) > 12); And even more importantly subqueries embedded in packaged applications no longer need to be re-written into joins.  This is good news for both ISVs and their customers who have access to the underlying queries and who have spent development cycles writing, testing and maintaining their own versions of re-written queries across updated versions of a packaged app.The details are in the MySQL 5.6 docs. Online DDL OperationsToday's web-based applications are designed to rapidly evolve and adapt to meet business and revenue-generationrequirements. As a result, development SLAs are now most often measured in minutes vs days or weeks. For example, when an application must quickly support new product lines or new products within existing product lines, the backend database schema must adapt in kind, and most commonly while the application remains available for normal business operations.  MySQL 5.6 supports this level of online schema flexibility and agility by providing the following new ALTER TABLE online DDL syntax additions:  CREATE INDEX DROP INDEX Change AUTO_INCREMENT value for a column ADD/DROP FOREIGN KEY Rename COLUMN Change ROW FORMAT, KEY_BLOCK_SIZE for a table Change COLUMN NULL, NOT_NULL Add, drop, reorder COLUMN Again, the details are in the MySQL 5.6 docs. Key-value access to InnoDB via Memcached APIMany of the next generation of web, cloud, social and mobile applications require fast operations against simple Key/Value pairs. At the same time, they must retain the ability to run complex queries against the same data, as well as ensure the data is protected with ACID guarantees. With the new NoSQL API for InnoDB, developers have allthe benefits of a transactional RDBMS, coupled with the performance capabilities of Key/Value store.MySQL 5.6 provides simple, key-value interaction with InnoDB data via the familiar Memcached API.  Implemented via a new Memcached daemon plug-in to mysqld, the new Memcached protocol is mapped directly to the native InnoDB API and enables developers to use existing Memcached clients to bypass the expense of query parsing and go directly to InnoDB data for lookups and transactional compliant updates.  The API makes it possible to re-use standard Memcached libraries and clients, while extending Memcached functionality by integrating a persistent, crash-safe, transactional database back-end.  The implementation is shown here:So does this option provide a performance benefit over SQL?  Internal performance benchmarks using a customized Java application and test harness show some very promising results with a 9X improvement in overall throughput for SET/INSERT operations:You can follow the InnoDB team blog for the methodology, implementation and internal test cases that generated these results here. How to get started with Memcached API to InnoDB is here. New Instrumentation in Performance SchemaThe MySQL Performance Schema was introduced in MySQL 5.5 and is designed to provide point in time metrics for key performance indicators.  MySQL 5.6 improves the Performance Schema in answer to the most common DBA and Developer problems.  New instrumentations include: Statements/Stages What are my most resource intensive queries? Where do they spend time? Table/Index I/O, Table Locks Which application tables/indexes cause the most load or contention? Users/Hosts/Accounts Which application users, hosts, accounts are consuming the most resources? Network I/O What is the network load like? How long do sessions idle? Summaries Aggregated statistics grouped by statement, thread, user, host, account or object. The MySQL 5.6 Performance Schema is now enabled by default in the my.cnf file with optimized and auto-tune settings that minimize overhead (< 5%, but mileage will vary), so using the Performance Schema ona production server to monitor the most common application use cases is less of an issue.  In addition, new atomic levels of instrumentation enable the capture of granular levels of resource consumption by users, hosts, accounts, applications, etc. for billing and chargeback purposes in cloud computing environments.The MySQL docs are an excellent resource for all that is available and that can be done with the 5.6 Performance Schema. Better Condition Handling - GET DIAGNOSTICSMySQL 5.6 enables developers to easily check for error conditions and code for exceptions by introducing the new MySQL Diagnostics Area and corresponding GET DIAGNOSTICS interface command. The Diagnostic Area can be populated via multiple options and provides 2 kinds of information:Statement - which provides affected row count and number of conditions that occurredCondition - which provides error codes and messages for all conditions that were returned by a previous operation The addressable items for each are: The new GET DIAGNOSTICS command provides a standard interface into the Diagnostics Area and can be used via the CLI or from within application code to easily retrieve and handle the results of the most recent statement execution.  An example of how it is used might be:mysql> DROP TABLE test.no_such_table; ERROR 1051 (42S02): Unknown table 'test.no_such_table' mysql> GET DIAGNOSTICS CONDITION 1 -> @p1 = RETURNED_SQLSTATE, @p2 = MESSAGE_TEXT; mysql> SELECT @p1, @p2; +-------+------------------------------------+| @p1   | @p2                                | +-------+------------------------------------+| 42S02 | Unknown table 'test.no_such_table' | +-------+------------------------------------+ Options for leveraging the MySQL Diagnotics Area and GET DIAGNOSTICS are detailed in the MySQL Docs.While the above is a summary of some of the key developer enabling 5.6 features, it is by no means exhaustive. You can dig deeper into what MySQL 5.6 has to offer by reading this developer zone article or checking out "What's New in MySQL 5.6" in the MySQL docs.BONUS ALERT!  If you are developing on Windows or are considering MySQL as an alternative to SQL Server for your next project, application or shipping product, you should check out the MySQL Installer for Windows.  The installer includes the MySQL 5.6 RC database, all drivers, Visual Studio and Excel plugins, tray monitor and development tools all a single download and GUI installer.   So what are your next steps? Register for Dec. 13 "MySQL 5.6: Building the Next Generation of Web-Based Applications and Services" live web event.  Hurry!  Seats are limited. Download the MySQL 5.6 Release Candidate (look under the Development Releases tab) Provide Feedback <link to http://bugs.mysql.com/> Join the Developer discussion on the MySQL Forums Explore all MySQL Products and Developer Tools As always, thanks for your continued support of MySQL!

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  • How Visual Studio 2010 and Team Foundation Server enable Compliance

    - by Martin Hinshelwood
    One of the things that makes Team Foundation Server (TFS) the most powerful Application Lifecycle Management (ALM) platform is the traceability it provides to those that use it. This traceability is crucial to enable many companies to adhere to many of the Compliance regulations to which they are bound (e.g. CFR 21 Part 11 or Sarbanes–Oxley.)   From something as simple as relating Tasks to Check-in’s or being able to see the top 10 files in your codebase that are causing the most Bugs, to identifying which Bugs and Requirements are in which Release. All that information is available and more in TFS. Although all of this tradability is available within TFS you do need to understand that it is not for free. Well… I say that, but if you are using TFS properly you will have this information with no additional work except for firing up the reporting. Using Visual Studio ALM and Team Foundation Server you can relate every line of code changes all the way up to requirements and back down through Test Cases to the Test Results. Figure: The only thing missing is Build In order to build the relationship model below we need to examine how each of the relationships get there. Each member of your team from programmer to tester and Business Analyst to Business have their roll to play to knit this together. Figure: The relationships required to make this work can get a little confusing If Build is added to this to relate Work Items to Builds and with knowledge of which builds are in which environments you can easily identify what is contained within a Release. Figure: How are things progressing Along with the ability to produce the progress and trend reports the tractability that is built into TFS can be used to fulfil most audit requirements out of the box, and augmented to fulfil the rest. In order to understand the relationships, lets look at each of the important Artifacts and how they are associated with each other… Requirements – The root of all knowledge Requirements are the thing that the business cares about delivering. These could be derived as User Stories or Business Requirements Documents (BRD’s) but they should be what the Business asks for. Requirements can be related to many of the Artifacts in TFS, so lets look at the model: Figure: If the centre of the world was a requirement We can track which releases Requirements were scheduled in, but this can change over time as more details come to light. Figure: Who edited the Requirement and when There is also the ability to query Work Items based on the History of changed that were made to it. This is particularly important with Requirements. It might not be enough to say what Requirements were completed in a given but also to know which Requirements were ever assigned to a particular release. Figure: Some magic required, but result still achieved As an augmentation to this it is also possible to run a query that shows results from the past, just as if we had a time machine. You can take any Query in the system and add a “Asof” clause at the end to query historical data in the operational store for TFS. select <fields> from WorkItems [where <condition>] [order by <fields>] [asof <date>] Figure: Work Item Query Language (WIQL) format In order to achieve this you do need to save the query as a *.wiql file to your local computer and edit it in notepad, but one imported into TFS you run it any time you want. Figure: Saving Queries locally can be useful All of these Audit features are available throughout the Work Item Tracking (WIT) system within TFS. Tasks – Where the real work gets done Tasks are the work horse of the development team, but they only as useful as Excel if you do not relate them properly to other Artifacts. Figure: The Task Work Item Type has its own relationships Requirements should be broken down into Tasks that the development team work from to build what is required by the business. This may be done by a small dedicated group or by everyone that will be working on the software team but however it happens all of the Tasks create should be a Child of a Requirement Work Item Type. Figure: Tasks are related to the Requirement Tasks should be used to track the day-to-day activities of the team working to complete the software and as such they should be kept simple and short lest developers think they are more trouble than they are worth. Figure: Task Work Item Type has a narrower purpose Although the Task Work Item Type describes the work that will be done the actual development work involves making changes to files that are under Source Control. These changes are bundled together in a single atomic unit called a Changeset which is committed to TFS in a single operation. During this operation developers can associate Work Item with the Changeset. Figure: Tasks are associated with Changesets   Changesets – Who wrote this crap Changesets themselves are just an inventory of the changes that were made to a number of files to complete a Task. Figure: Changesets are linked by Tasks and Builds   Figure: Changesets tell us what happened to the files in Version Control Although comments can be changed after the fact, the inventory and Work Item associations are permanent which allows us to Audit all the way down to the individual change level. Figure: On Check-in you can resolve a Task which automatically associates it Because of this we can view the history on any file within the system and see how many changes have been made and what Changesets they belong to. Figure: Changes are tracked at the File level What would be even more powerful would be if we could view these changes super imposed over the top of the lines of code. Some people call this a blame tool because it is commonly used to find out which of the developers introduced a bug, but it can also be used as another method of Auditing changes to the system. Figure: Annotate shows the lines the Annotate functionality allows us to visualise the relationship between the individual lines of code and the Changesets. In addition to this you can create a Label and apply it to a version of your version control. The problem with Label’s is that they can be changed after they have been created with no tractability. This makes them practically useless for any sort of compliance audit. So what do you use? Branches – And why we need them Branches are a really powerful tool for development and release management, but they are most important for audits. Figure: One way to Audit releases The R1.0 branch can be created from the Label that the Build creates on the R1 line when a Release build was created. It can be created as soon as the Build has been signed of for release. However it is still possible that someone changed the Label between this time and its creation. Another better method can be to explicitly link the Build output to the Build. Builds – Lets tie some more of this together Builds are the glue that helps us enable the next level of tractability by tying everything together. Figure: The dashed pieces are not out of the box but can be enabled When the Build is called and starts it looks at what it has been asked to build and determines what code it is going to get and build. Figure: The folder identifies what changes are included in the build The Build sets a Label on the Source with the same name as the Build, but the Build itself also includes the latest Changeset ID that it will be building. At the end of the Build the Build Agent identifies the new Changesets it is building by looking at the Check-ins that have occurred since the last Build. Figure: What changes have been made since the last successful Build It will then use that information to identify the Work Items that are associated with all of the Changesets Changesets are associated with Build and change the “Integrated In” field of those Work Items . Figure: Find all of the Work Items to associate with The “Integrated In” field of all of the Work Items identified by the Build Agent as being integrated into the completed Build are updated to reflect the Build number that successfully integrated that change. Figure: Now we know which Work Items were completed in a build Now that we can link a single line of code changed all the way back through the Task that initiated the action to the Requirement that started the whole thing and back down to the Build that contains the finished Requirement. But how do we know wither that Requirement has been fully tested or even meets the original Requirements? Test Cases – How we know we are done The only way we can know wither a Requirement has been completed to the required specification is to Test that Requirement. In TFS there is a Work Item type called a Test Case Test Cases enable two scenarios. The first scenario is the ability to track and validate Acceptance Criteria in the form of a Test Case. If you agree with the Business a set of goals that must be met for a Requirement to be accepted by them it makes it both difficult for them to reject a Requirement when it passes all of the tests, but also provides a level of tractability and validation for audit that a feature has been built and tested to order. Figure: You can have many Acceptance Criteria for a single Requirement It is crucial for this to work that someone from the Business has to sign-off on the Test Case moving from the  “Design” to “Ready” states. The Second is the ability to associate an MS Test test with the Test Case thereby tracking the automated test. This is useful in the circumstance when you want to Track a test and the test results of a Unit Test designed to test the existence of and then re-existence of a a Bug. Figure: Associating a Test Case with an automated Test Although it is possible it may not make sense to track the execution of every Unit Test in your system, there are many Integration and Regression tests that may be automated that it would make sense to track in this way. Bug – Lets not have regressions In order to know wither a Bug in the application has been fixed and to make sure that it does not reoccur it needs to be tracked. Figure: Bugs are the centre of their own world If the fix to a Bug is big enough to require that it is broken down into Tasks then it is probably a Requirement. You can associate a check-in with a Bug and have it tracked against a Build. You would also have one or more Test Cases to prove the fix for the Bug. Figure: Bugs have many associations This allows you to track Bugs / Defects in your system effectively and report on them. Change Request – I am not a feature In the CMMI Process template Change Requests can also be easily tracked through the system. In some cases it can be very important to track Change Requests separately as an Auditor may want to know what was changed and who authorised it. Again and similar to Bugs, if the Change Request is big enough that it would require to be broken down into Tasks it is in reality a new feature and should be tracked as a Requirement. Figure: Make sure your Change Requests only Affect Requirements and not rewrite them Conclusion Visual Studio 2010 and Team Foundation Server together provide an exceptional Application Lifecycle Management platform that can help your team comply with even the harshest of Compliance requirements while still enabling them to be Agile. Most Audits are heavy on required documentation but most of that information is captured for you as long a you do it right. You don’t even need every team member to understand it all as each of the Artifacts are relevant to a different type of team member. Business Analysts manage Requirements and Change Requests Programmers manage Tasks and check-in against Change Requests and Bugs Testers manage Bugs and Test Cases Build Masters manage Builds Although there is some crossover there are still rolls or “hats” that are worn. Do you thing this is all achievable? Have I missed anything that you think should be there?

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