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• 64-bit linux kernel only seeing 3 of 4GB after upgrade...

  - by Blaine

  Hey everyone. I am running Ubuntu 9.04 64-bit on my macbook. I had 2GB of ram before, and everything ran great. I just upgraded to 2x2GB (4GB), but my system only sees 3GB of it. OS X, which I am dual booting, sees all 4GB. Also, my video performance is incredibly lacking. Before the upgrade my compiz benchmark was full at 80fps, and now it is at 22fps with very choppy window dragging. Has anyone ever heard of this on a 64-bit kernel? I just don't quite understand what could be the issue. 10$ uname -a Linux macbook 2.6.28-15-generic #49-Ubuntu SMP Tue Aug 18 19:25:34 UTC 2009 x86_64 GNU/Linux $ free -m total used free shared buffers cached Mem: 2953 1031 1921 0 114 427 -/+ buffers/cache: 489 2463 Swap: 7812 0 7812 9$ lsmod Module Size Used by i915 77960 2 drm 123232 3 i915 binfmt_misc 18572 1 ppdev 16904 0 btusb 21784 2 bridge 63776 0 stp 11140 1 bridge bnep 22912 2 vboxnetadp 109356 0 vboxnetflt 116972 0 vboxdrv 1721612 1 vboxnetflt uvcvideo 69640 0 compat_ioctl32 18304 1 uvcvideo videodev 45184 2 uvcvideo,compat_ioctl32 v4l1_compat 23940 2 uvcvideo,videodev lp 19588 0 parport 49584 2 ppdev,lp snd_hda_intel 557492 3 snd_pcm_oss 52352 0 snd_mixer_oss 24960 1 snd_pcm_oss snd_pcm 99464 2 snd_hda_intel,snd_pcm_oss arc4 10240 2 snd_seq_dummy 11524 0 ecb 11392 2 snd_seq_oss 41984 0 snd_seq_midi 15744 0 snd_rawmidi 33920 1 snd_seq_midi snd_seq_midi_event 16512 2 snd_seq_oss,snd_seq_midi snd_seq 66272 6 snd_seq_dummy,snd_seq_oss,snd_seq_midi,snd_seq_midi_event ath9k 310584 0 snd_timer 34064 2 snd_pcm,snd_seq snd_seq_device 16276 5 snd_seq_dummy,snd_seq_oss,snd_seq_midi,snd_rawmidi,snd_seq mac80211 251528 1 ath9k iTCO_wdt 21712 0 iTCO_vendor_support 12420 1 iTCO_wdt joydev 20992 0 video 29204 0 snd 78920 15 snd_hda_intel,snd_pcm_oss,snd_mixer_oss,snd_pcm,snd_seq_oss,snd_rawmidi,snd_seq,snd_timer,snd_seq_device applesmc 37700 0 output 11648 1 video soundcore 16800 1 snd pcspkr 11136 0 cfg80211 43680 1 mac80211 appletouch 19972 0 isight_firmware 11520 0 input_polldev 12688 1 applesmc intel_agp 39408 1 snd_page_alloc 18704 2 snd_hda_intel,snd_pcm led_class 13064 2 ath9k,applesmc hid_apple 15872 0 usbhid 47040 0 ohci1394 42164 0 ieee1394 108288 1 ohci1394 sky2 63364 0 fbcon 49792 0 tileblit 11264 1 fbcon font 17024 1 fbcon bitblit 14464 1 fbcon softcursor 10368 1 bitblit Some information from dmesg: [ 795.820163] ACPI: EC: GPE storm detected, transactions will use polling mode [ 1762.709516] [drm:i915_getparam] *ERROR* Unknown parameter 6 [ 1763.078130] [drm:i915_getparam] *ERROR* Unknown parameter 6 [ 2362.760889] [drm:i915_getparam] *ERROR* Unknown parameter 6 [ 2416.352084] ACPI: EC: missing confirmations, switch off interrupt mode. [ 3718.721095] [drm:i915_getparam] *ERROR* Unknown parameter 6 [ 3719.108914] [drm:i915_getparam] *ERROR* Unknown parameter 6 [ 4318.773266] [drm:i915_getparam] *ERROR* Unknown parameter 6 [ 9513.813066] CE: hpet increasing min_delta_ns to 15000 nsec [ 9693.815684] npviewer.bin[6736]

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• USB Flash not recognised by Windows and BIOS, but works fine in Linux

  - by bbalegere

  I have a Transcend JetFLash 2GB USB Drive.It was working fine and I had been using it occasionally. All of sudden it stopped working in all versions of Windows . The USB Drive is also not recognised by the BIOS.It does not show in the list of bootable devices.(It used show up in the list earlier) However the USB Drive works fine in my Linux Mint 11 OS. Running dmesg gives this [ 941.812192] usb 1-2: new high speed USB device using ehci_hcd and address 4 [ 941.936178] usb 1-2: device descriptor read/64, error -71 [ 942.164188] usb 1-2: device descriptor read/64, error -71 [ 942.380189] usb 1-2: new high speed USB device using ehci_hcd and address 5 [ 942.504138] usb 1-2: device descriptor read/64, error -71 [ 942.732179] usb 1-2: device descriptor read/64, error -71 [ 942.948154] usb 1-2: new high speed USB device using ehci_hcd and address 6 [ 943.364134] usb 1-2: device not accepting address 6, error -71 [ 943.476172] usb 1-2: new high speed USB device using ehci_hcd and address 7 [ 943.892140] usb 1-2: device not accepting address 7, error -71 [ 943.892191] hub 1-0:1.0: unable to enumerate USB device on port 2 [ 944.296190] usb 2-2: new full speed USB device using uhci_hcd and address 3 [ 944.438251] usb 2-2: not running at top speed; connect to a high speed hub [ 944.709928] usbcore: registered new interface driver uas [ 944.729999] Initializing USB Mass Storage driver... [ 944.730509] scsi6 : usb-storage 2-2:1.0 [ 944.730908] usbcore: registered new interface driver usb-storage [ 944.730917] USB Mass Storage support registered. [ 945.736320] scsi 6:0:0:0: Direct-Access JetFlash Transcend 2GB 8.07 PQ: 0 ANSI: 2 [ 945.744547] sd 6:0:0:0: Attached scsi generic sg1 type 0 [ 945.753316] sd 6:0:0:0: [sdb] 3944448 512-byte logical blocks: (2.01 GB/1.88 GiB) [ 945.758274] sd 6:0:0:0: [sdb] Write Protect is off [ 945.758288] sd 6:0:0:0: [sdb] Mode Sense: 03 00 00 00 [ 945.765167] sd 6:0:0:0: [sdb] No Caching mode page present [ 945.765181] sd 6:0:0:0: [sdb] Assuming drive cache: write through [ 945.784309] sd 6:0:0:0: [sdb] No Caching mode page present [ 945.784323] sd 6:0:0:0: [sdb] Assuming drive cache: write through [ 946.239512] sdb: sdb1 [ 946.257279] sd 6:0:0:0: [sdb] No Caching mode page present [ 946.257292] sd 6:0:0:0: [sdb] Assuming drive cache: write through [ 946.257302] sd 6:0:0:0: [sdb] Attached SCSI removable disk Looks like there is something wrong the USB Drive.It is not recognised in any computer running Windows. Is there any way to fix this? Any idea why this problem occurred ?

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• grep simply fails when used on a few files

  - by Reid

  I've been trying for about the past 30 minutes to get this to work properly. grep is not exactly the most difficult thing to use, so I'm somewhat baffled as to why this won't work. The files I'm trying to use grep on are simple XHTML log files. Their names are in the format [email protected], though I don't think that should matter, and inside is simple XHTML. I copied one such log file to be testfile so you can see the output of some commands and why it's baffling to me: [~/.chatlogs_windows/dec] > whoami reid [~/.chatlogs_windows/dec] > type grep grep is /bin/grep [~/.chatlogs_windows/dec] > uname -a Linux reid-pc 2.6.35-22-generic #33-Ubuntu SMP Sun Sep 19 20:32:27 UTC 2010 x86_64 GNU/Linux [~/.chatlogs_windows/dec] > head -1 /etc/issue Linux Mint 10 Julia [~/.chatlogs_windows/dec] > ls -Alh | grep testfile -rw-r--r-- 1 reid reid 63K 2011-01-10 12:45 testfile [~/.chatlogs_windows/dec] > tail -3 testfile </body> </html> [~/.chatlogs_windows/dec] > file testfile testfile: XML document text [~/.chatlogs_windows/dec] > grep html testfile [~/.chatlogs_windows/dec] > grep body testfile [~/.chatlogs_windows/dec] > grep "</html>" testfile [~/.chatlogs_windows/dec] > grep "</body>" testfile [~/.chatlogs_windows/dec] > cat testfile | grep html [~/.chatlogs_windows/dec] > cat testfile | wc -l 231 [~/.chatlogs_windows/dec] > cat testfile | tail -3 </body> </html> [~/.chatlogs_windows/dec] > chmod a+rw testfile && ls -Alh | grep testfile -rw-rw-rw- 1 reid reid 63K 2011-01-10 12:45 testfile [~/.chatlogs_windows/dec] > grep html testfile That's what I'm attempting to do. I want to just use grep -ri query . in ~/.chatlogs_windows, which normally works perfectly for me... but for some reason, it completely fails at going through these files. If it matters, I copied these files off of my Windows 7 partition. But I chown'd them and gave myself all the appropriate permissions, and other programs (like cat) seem to read them just fine. I also copied testfile to testfile_unix and converted the line endings and tried that, but it didn't work either. I'm using zsh, but I tried it on bash and that failed too. Also, grep works normally: I tried it out on my documents folder and it worked flawlessly. If you need any more information, just let me know. I tried googling around, but I found no reason for grep to simply not work. Thanks in advance.

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• RSH between servers not working

  - by churnd

  I have two servers: one CentOS 5.8 & one Solaris 10. Both are joined to my workplace AD domain via PBIS-Open. A user will log into the linux server & run an application which issues commands over RSH to the solaris server. Some commands are also run on the linux server, so both are needed. Due to the application these servers are being used for (proprietary GE software), the software on the linux server needs to be able to issue rsh commands to the solaris server on behalf of the user (the user just runs a script & the rest is automatic). However, rsh is not working for the domain users. It does work for a local user, so I believe I have the necessary trust settings between the two servers correct. However, I can rlogin as a domain user from the linux server to the solaris server. SSH works too (how I wish I could use it). Some relevant info: via rlogin: [user@linux~]$ rlogin solaris connect to address 192.168.1.2 port 543: Connection refused Trying krb4 rlogin... connect to address 192.168.1.2 port 543: Connection refused trying normal rlogin (/usr/bin/rlogin) Sun Microsystems Inc. SunOS 5.10 Generic January 2005 solaris% via rsh: [user@linux ~]$ rsh solaris ls connect to address 192.168.1.2 port 544: Connection refused Trying krb4 rsh... connect to address 192.168.1.2 port 544: Connection refused trying normal rsh (/usr/bin/rsh) permission denied. [user@linux ~]$ relevant snippet from /etc/pam.conf on solaris: # # rlogin service (explicit because of pam_rhost_auth) # rlogin auth sufficient pam_rhosts_auth.so.1 rlogin auth requisite pam_lsass.so set_default_repository rlogin auth requisite pam_lsass.so smartcard_prompt try_first_pass rlogin auth requisite pam_authtok_get.so.1 try_first_pass rlogin auth sufficient pam_lsass.so try_first_pass rlogin auth required pam_dhkeys.so.1 rlogin auth required pam_unix_cred.so.1 rlogin auth required pam_unix_auth.so.1 # # Kerberized rlogin service # krlogin auth required pam_unix_cred.so.1 krlogin auth required pam_krb5.so.1 # # rsh service (explicit because of pam_rhost_auth, # and pam_unix_auth for meaningful pam_setcred) # rsh auth sufficient pam_rhosts_auth.so.1 rsh auth required pam_unix_cred.so.1 # # Kerberized rsh service # krsh auth required pam_unix_cred.so.1 krsh auth required pam_krb5.so.1 # I have not really seen anything useful in either system log that seem to be directly related to the failed login attempt. I've tail -f'd /var/adm/messages on solaris & /var/log/messages on linux during the failed attempts & nothing shows up. Maybe I need to be doing something else?

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• configuring slime in emacs

  - by CodeKingPlusPlus

  I am in the process of configuring slime for emacs. So far I have read about basic functionality for common lisp such as C-c C-q which invokes the command slime-close-parens-at-point which places the proper number of parens where your mouse is. Another command that seemed cool was invoked by C-c C-c and it would pass the code you are editing in a buffer to the REPL, and "compile" it. Why won't these commands work for me? Anyway, I have downloaded slime via M-x list-packages and do not seem to have this functionality (C-h w and then any of these commands tells me that these commands do note exist). So, I saw a bunch of other slime extensions such as slime-repl', 'slime-fuzzy' and 'hippie-expand-slime'. So I again usedM-x list-packages` and downloaded them. Still I did not have these commands. Here is the content of my emacs file relevant to slime: ;;;Common Lisp and Slime (add-to-list 'load-path "/home/s2s2/.emacs.d/elpa/slime-20130626.1151") (add-to-list 'load-path "/home/s2s2/.emacs.d/elpa/slime-repl-201000404") (add-to-list 'load-path "/home/s2s2/.emacs.d/elpa/hippie-expand-slime-20130226.1656") (add-to-list 'load-path "/home/s2s2/.emacs.d/elpa/slime-fuzzy-20100404") (require 'slime) (setq slime-lisp-implementations `((sbcl ("/usr/bin/sbcl")) (ecl ("/usr/bin/ecl")) (clisp ("/usr/bin/clisp" "-q -I")))) (require 'slime-repl) (require 'slime-fuzzy) (require 'hippie-expand-slime) When I execute M-x slime I get the following message in the inferior-lisp buffer where I can execute common lisp code (however, shouldn't this be the slime-repl since I required it?): STYLE-WARNING: redefining EMACS-INSPECT (#<BUILT-IN-CLASS T>) in DEFMETHOD STYLE-WARNING: Implicitly creating new generic function STREAM-READ-CHAR-WILL-HANG-P. WARNING: These Swank interfaces are unimplemented: (DISASSEMBLE-FRAME SLDB-BREAK-AT-START SLDB-BREAK-ON-RETURN) ;; Swank started at port: 46533. Then a slime-error buffer is created with the contents: Invalid protocol message: Symbol "CREATE-REPL" not found in the SWANK package. Line: 1, Column: 28, File-Position: 28 Stream: #<SB-IMPL::STRING-INPUT-STREAM {10056B9C33}> (:emacs-rex (swank:create-repl nil) "COMMON-LISP-USER" t 5) How should I modify my emacs file to give me the functionality of those commands? In my emacs file am I not loading the necessary files? Do I need to install an additional package? If you need more information let me know! All help is much appreciated!

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• Inconsistent file downloads of (what should be) the same file

  - by Austin A.

  I'm working on a system that archives large collections of timetstamped images. Part of the system deals with saving an image to a growing .zip file. This morning I noticed that the log system said that an image was successfully downloaded and placed in the zip file, but when I downloaded the .zip (from an apache alias running on our server), the images didn't match the log. For example, although the log said that camera 3484 captured on January 17, 2011, when I download from the apache alias, the downloaded zip file only contains images up to January 14. So, I sshed onto the server, and unzipped the file in its own directory, and that zip file has images from January 14 to today (January 17). What strikes me as odd is that this should be the exact same file as the one I downloaded from the apache alias. Other experiments: I scp-ed the file from the server to my local machine, and the zip file has the newer images. But when I use an SCP client (in this case, Fugu for OSX), I get the zip file for the older images. In short: unzipping a file on the server or after downloading through scp or after downloading through wget gives one zip file, but unzipping a file from Chrome, Firefox, or SCP client gives a different zip file, when they should be exactly the same. Unzipping on the server... [user@server ~]$ cd /export1/amos/images/2011/84/3484/00003484/ [user@server 00003484]$ ls -la total 6180 drwxr-sr-x 2 user groupname 24 Jan 17 11:20 . drwxr-sr-x 4 user groupname 36 Jan 11 19:58 .. -rw-r--r-- 1 user groupname 6309980 Jan 17 12:05 2011.01.zip [user@server 00003484]$ unzip 2011.01.zip Archive: 2011.01.zip extracting: 20110114_140547.jpg extracting: 20110114_143554.jpg replace 20110114_143554.jpg? [y]es, [n]o, [A]ll, [N]one, [r]ename: y extracting: 20110114_143554.jpg extracting: 20110114_153458.jpg (...bunch of files...) extracting: 20110117_170459.jpg extracting: 20110117_173458.jpg extracting: 20110117_180501.jpg Using the wget through apache alias. local:~ user$ wget http://example.com/zipfiles/2011/84/3484/00003484/2011.01.zip --12:38:13-- http://example.com/zipfiles/2011/84/3484/00003484/2011.01.zip => `2011.01.zip' Resolving example.com... ip.ip.ip.ip Connecting to example.com|ip.ip.ip.ip|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 6,327,747 (6.0M) [application/zip] 100% [=====================================================================================================>] 6,327,747 1.03M/s ETA 00:00 12:38:56 (143.23 KB/s) - `2011.01.zip' saved [6327747/6327747] local:~ user$ unzip 2011.01.zip Archive: 2011.01.zip extracting: 20110114_140547.jpg (... same as before...) extracting: 20110117_183459.jpg Using scp to grab the zip local:~ user$ scp user@server:/export1/amos/images/2011/84/3484/00003484/2011.01.zip . 2011.01.zip 100% 6179KB 475.3KB/s 00:13 local:~ user$ unzip 2011.01.zip Archive: 2011.01.zip extracting: 20110114_140547.jpg (...same as before...) extracting: 20110117_183459.jpg Using Fugu to download 2011.01.zip from /export1/amos/images/2011/84/3484/00003484/ gives images 20110113_090457.jpg through 201100114_010554.jpg Using Firefox to download 2011.01.zip from http://example.com/zipfiles/2011/84/3484/00003484/2011.01.zip gives images 20110113_090457.jpg through 201100114_010554.jpg Using Chrome gives same results as Firefox. Relevant section from apache httpd.conf: # ScriptAlias: This controls which directories contain server scripts. # ScriptAliases are essentially the same as Aliases, except that # documents in the realname directory are treated as applications and # run by the server when requested rather than as documents sent to the client. # The same rules about trailing "/" apply to ScriptAlias directives as to # Alias. # ScriptAlias /cgi-bin/ "/var/www/cgi-bin/" Alias /zipfiles/ /export1/amos/images/

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• CakePHP in a subdirectory using nginx (Rewrite rules?)

  - by lhnz

  I managed to get this to work a while back, but on returning to the cakephp project I had started it seems that whatever changes I've made to nginx recently (or perhaps a recent update) have broken my rewrite rules. Currently I have: worker_processes 1; events { worker_connections 1024; } http { include mime.types; default_type application/octet-stream; sendfile on; keepalive_timeout 65; server { listen 80; server_name localhost; location / { root html; index index.php index.html index.htm; } location /basic_cake/ { index index.php; if (-f $request_filename) { break; } if (!-f $request_filename) { rewrite ^/basic_cake/(.+)$ /basic_cake/index.php?url=$1 last; break; } } location /cake_test/ { index index.php; if (-f $request_filename) { break; } if (!-f $request_filename) { rewrite ^/cake_test/(.+)$ /cake_test/index.php?url=$1 last; break; } } # redirect server error pages to the static page /50x.html # error_page 500 502 503 504 /50x.html; location = /50x.html { root html; } # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000 # location ~ \.php$ { root html; fastcgi_pass 127.0.0.1:9000; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; include fastcgi_params; } } server { listen 8081; server_name localhost; root /srv/http/html/xsp; location / { index index.html index.htm index.aspx default.aspx; } location ~ \.(aspx|asmx|ashx|asax|ascx|soap|rem|axd|cs|config|dll)$ { fastcgi_pass 127.0.0.1:9001; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; include fastcgi_params; } } } The problem that I have is that the css and images will not load from the webroot. Instead if I visit http://localhost/basic_cake/css/cake.generic.css, I get a page which tells me: CakePHP: the rapid development php framework Missing Controller Error: CssController could not be found. Error: Create the class CssController below in file: app/controllers/css_controller.php var $name = 'Css'; } ? Notice: If you want to customize this error message, create app/views/errors/missing_controller.ctp CakePHP: the rapid development php framework Does anybody have any ideas on how to fix this?

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• Bypassing "Found New Hardware Wizard" / Setting Windows to Install Drivers Automatically

  - by Synetech inc.

  Hi, My motherboard finally died after the better part of a decade, so I bought a used system. I put my old hard-drive and sound-card in the new system, and connected my old keyboard and mouse (the rest of the components—CPU, RAM, mobo, video card—are from the new system). I knew beforehand that it would be a challenge to get Windows to boot and install drivers for the new hardware (particularly since the foundational components are new), but I am completely unable to even attempt to get through the work of installing drivers for things like the video card because the keyboard and mouse won't work (they do work, in the BIOS screen, in DOS mode, in Windows 7, in XP's boot menu, etc., just not in Windows XP itself). Whenever I try to boot XP (in normal or safe mode), I get a bunch of balloons popping up for all the new hardware detected, and a New Hardware Found Wizard for Processor (obviously it has to install drivers for the lowest-level components on up). Unfortunately I cannot click Next since the keyboard and mouse won't work yet because the motherboard drivers (for the PS/2 or USB ports) are not yet installed. I even tried a serial mouse, but to no avail—again, it does work in DOS, 7, etc., but not XP because it doesn't have the serial port driver installed. I tried mounting the SOFTWARE and SYSTEM hives under Windows 7 in order to manually set the "unsigned drivers warning" to ignore (using both of the driver-signing policy settings that I found references to). That didn't work; I still get the wizard. They are not even fancy, proprietary, third-party, or unsigned drivers. They are drivers that come with Windows—as the drivers for CPU, RAM, IDE controller, etc. tend to be. And the keyboard and mouse drivers are the generic ones at that (but like I said, those are irrelevant since the drivers for the ports that they are connected to are not yet installed). Obviously at some point in time over the past several years, a setting got changed to make Windows always prompt me when it detects new hardware. (It was also configured to show the Shutdown Event Tracker on abnormal shutdowns, so I had to turn that off so that I could even see the desktop.) Oh, and I tried deleting all of the PNF files so that they get regenerated, but that too did not help. Does anyone know how I can reset Windows to at least try to automatically install drivers for new hardware before prompting me if it fails? Conversely, does anyone know how exactly one turns off automatic driver installation (and prompt with the wizard)? Thanks a lot.

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• Package problems after upgrade

  - by Dan

  I installed a new upgrade on ubuntu which seemed to fail near the end. Now I'm being told that an error has occurred and to please run apt-get to see what's wrong. After some further tries with that I eventually gave up. It seems there's a left over latex package(?) somewhere and I can't seem to get rid of or fix it. Here's an example: blank@ubuntu:~$ sudo apt-get dist-upgrade Reading package lists... Done Building dependency tree Reading state information... Done You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies: tex-common : Breaks: texlive-common (< 2010) but 2009-15 is installed texlive-base : Depends: texlive-binaries (>= 2012.20120516) but 2009-11ubuntu2 is installed Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed texlive-doc-base : Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed texlive-extra-utils : Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed Depends: texlive-binaries (>= 2012-0) but 2009-11ubuntu2 is installed texlive-font-utils : Depends: texlive-binaries (>= 2012-0) but 2009-11ubuntu2 is installed Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed texlive-generic-recommended : Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed texlive-latex-base : Depends: texlive-binaries (>= 2012-0) but 2009-11ubuntu2 is installed Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed texlive-latex-base-doc : Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed texlive-latex-extra : Depends: texlive-binaries (>= 2012-0) but 2009-11ubuntu2 is installed Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed texlive-latex-extra-doc : Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed texlive-latex-recommended : Depends: texlive-binaries (>= 2012-0) but 2009-11ubuntu2 is installed Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed texlive-latex-recommended-doc : Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed texlive-luatex : Depends: texlive-binaries (>= 2012-0) but 2009-11ubuntu2 is installed Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed texlive-pictures : Depends: texlive-binaries (>= 2012-0) but 2009-11ubuntu2 is installed Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed texlive-pictures-doc : Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed texlive-pstricks : Depends: texlive-binaries (>= 2012-0) but 2009-11ubuntu2 is installed Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed texlive-pstricks-doc : Depends: texlive-common (>= 2012.20120516) but 2009-15 is installed zlib1g : Breaks: texlive-binaries (< 2009-12) but 2009-11ubuntu2 is installed zlib1g:i386 : Breaks: texlive-binaries (< 2009-12) but 2009-11ubuntu2 is installed E: Unmet dependencies. Try using -f. I've seen similar errors on the site here, but not close enough that i could get it fixed. Any help would be great, Thanks

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• XCP Project Kronos syslog error: "irq ... : nobody cared" on Dom0 host

  - by Vlad Fedin

  One of our production clusters driven by XCP suddenly went uresponsive. After restart and some investigation we found such logs in dom0 machine syslog: Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659040] irq 339: nobody cared (try booting with the "irqpoll" option) Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659058] Pid: 0, comm: swapper/3 Tainted: G C O 3.2.0-24-generic #37-Ubuntu Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659060] Call Trace: Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659062] <IRQ> [<ffffffff810db37d>] __report_bad_irq+0x3d/0xe0 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659071] [<ffffffff810db605>] note_interrupt+0x135/0x190 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659074] [<ffffffff810d8e69>] handle_irq_event_percpu+0xa9/0x220 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659078] [<ffffffff8130ff3b>] ? radix_tree_lookup+0xb/0x10 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659081] [<ffffffff810d9031>] handle_irq_event+0x51/0x80 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659084] [<ffffffff810dc187>] handle_edge_irq+0x87/0x140 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659089] [<ffffffff813a8829>] __xen_evtchn_do_upcall+0x199/0x250 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659092] [<ffffffff813aa96f>] xen_evtchn_do_upcall+0x2f/0x50 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659096] [<ffffffff81666d3e>] xen_do_hypervisor_callback+0x1e/0x30 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659097] <EOI> [<ffffffff810013aa>] ? hypercall_page+0x3aa/0x1000 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659104] [<ffffffff810013aa>] ? hypercall_page+0x3aa/0x1000 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659107] [<ffffffff8100a1d0>] ? xen_safe_halt+0x10/0x20 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659110] [<fff IRQ 339 in cat /proc/interrupts: 339: ... xen-pirq-msi-x eth0 where eth0 is hardware NIC. While host machine seems to hang, guest machines continue to work, so our tiny internal monitoring on one of the virtual hosts logged something like that: [2012-10-26 20:31:51] [OK......] 200 OK : 113159149 ns [2012-10-26 20:32:40] [DISASTER] 500 Can't connect to [hostname]:80 (No route to host) : 47763284432 ns ... [2012-10-26 20:34:40] [DISASTER] 500 Can't connect to [hostname]:80 (No route to host) : 46894835070 ns [2012-10-26 20:34:57] [DISASTER] 500 Can't connect to [hostname]:80 (Bad hostname) : 16821741955 ns ... [2012-10-26 20:38:18] [DISASTER] 500 Can't connect to [hostname]:80 (Bad hostname) : 20103298289 ns [2012-10-26 20:38:37] [DISASTER] 500 Can't connect to [hostname]:80 (Bad hostname) : 17895754943 ns Host and guest OS: Ubuntu 12.04 LTS, 05:00.0 Ethernet controller: Intel Corporation 82574L Gigabit Network Connection Subsystem: ASUSTeK Computer Inc. Device 8369 Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+ Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx+ Latency: 0, Cache Line Size: 64 bytes Interrupt: pin A routed to IRQ 17 Region 0: Memory at fe500000 (32-bit, non-prefetchable) [size=128K] Region 2: I/O ports at e000 [size=32] Region 3: Memory at fe520000 (32-bit, non-prefetchable) [size=16K] Capabilities: <access denied> Kernel driver in use: e1000e Kernel modules: e1000e Any hints how to debug this?

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• Nagios core Event Handler not working

  - by sivashanmugam

  Nagios Event Handler is not triggering when the service is taking more time to response or down. My configuration in below nagios.cfg enable_event_handlers=1 localhost.cfg define service { use generic-service host_name Server service_description test-server servicegroups test-service check_command check-service is_volatile 0 check_period 24x7 max_check_attempts 4 normal_check_interval 2 retry_check_interval 2 contact_groups testcontacts notification_period 24x7 notification_options w,u,c,r notifications_enabled 1 event_handler_enabled 1 event_handler recheck-service } command.cfg define command{ command_name recheck-service command_line /usr/local/nagios/libexec/alert.sh $SERVICESTATE$ $SERVICESTATETYPE$ $SERVICEATTEMPT$ } alert.sh file !/bin/sh set -x case "$1" in OK) # The service just came back up, so don't do anything... ;; WARNING) # We don't really care about warning states, since the service is probably still running... ;; UNKNOWN) # We don't know what might be causing an unknown error, so don't do anything... ;; CRITICAL) Aha! The HTTP service appears to have a problem - perhaps we should restart the server... Is this a "soft" or a "hard" state? case "$2" in We're in a "soft" state, meaning that Nagios is in the middle of retrying the check before it turns into a "hard" state and contacts get notified... SOFT) # What check attempt are we on? We don't want to restart the web server on the first check, because it may just be a fluke! case "$3" in Wait until the check has been tried 3 times before restarting the web server. If the check fails on the 4th time (after we restart the web server), the state type will turn to "hard" and contacts will be notified of the problem. Hopefully this will restart the web server successfully, so the 4th check will result in a "soft" recovery. If that happens no one gets notified because we fixed the problem! 3) echo -n "Going To Ping the Virtual Machine (3rd soft critical state)..." # Call the init script to restart the HTTPD server myresult=`/usr/local/nagios/libexec/check_http xyz.com -t 100 | grep 'time'| awk '{print $10}'` echo "Your Service Is taking the following time Delay" "$myresult Seconds" |mail -s "WARNING : Service Taken More Time To Response" [email protected] ;; esac ;; # The HTTP service somehow managed to turn into a hard error without getting fixed. # It should have been restarted by the code above, but for some reason it didn't. # Let's give it one last try, shall we? # Note: Contacts have already been notified of a problem with the service at this

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• Recognizing Dell EquilLogic with Nagios

  - by user3677595

  EDIT: All firmware and models are compatible, that is why nothing is posted about it. Okay, so there will be a lot here, so please bare with me. I've been working on this now for a few hours (reading manuals and such) so I'm not just coming here right out of the blue. I am working on a PRE-EXISTING Nagios server where there are several other existing plugins and checks running and working. Now I want to add another server there to check so I made the following modifications: First and foremost, I added a file to /usr/local/nagios/libexec named: check_equallogic.sh. The permissions are 755, the same as all others. I have chowned to nagios:nagios and in the listing it shows the Owner as Nagios. I then added a command to the commands.cfg file in \usr\local\nagios\etc\objects that shows the following: # 'check_equallogic' command definition define command{ command_name check_equallogic command_line $USER1$/check_equallogic -H $HOSTADDRESS$ -C $ARG1$ -t $ARG2$ $ARG3$ } Following this, I created a file named equallogic.cfg in the objects directory and it contains (more or less): define host{ use linux-server ; Inherit default values from a template host_name 172.16.50.11 ; The name we're giving to this device alias EqualLogic ; A longer name associated with the device address 172.16.50.11 ; IP address of the device contact_groups admins } Check Equallogic Information define service{ use generic-service host_name 172.16.50.11 service_description General Information check_command check_equallogic!public!info } After ensuring that permissions are okay for all files, I restart the nagios service, no errors. When I go into the WebGUI, I get the following errors AFTER the check runs: (Return code of 127 is out of bounds - plugin may be missing) Extra, probably unrelated problem Furthermore, when I log into the EquilLogic server, under Audit logs I get the following error: Level: AUDIT Time: 26/05/2014 3:59:13 PM Member: ps4100-1 Subsystem: agent Event ID: 22.7.1 SNMP packet validation failed, request received from 172.16.10.11 An snmpwalk receives a timeout, whereas others succeed. I will work on importing the MIBs tomorrow. The reason why I am mentioning it is because I want to make sure that it is only a MIB issue for the SNMP. If it is, then ignore this area. I am entirely unsure of what to do here.

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• Ubuntu hardware wireless switch has no effect after suspend and 13.10 upgrade

  - by blaineh

  I'm posting this on SU after it stalled on askubuntu. I hope someone here can help! If you'd prefer to answer on AU itself, here's the link: http://askubuntu.com/questions/365177/hardware-wireless-switch-has-no-effect-after-suspend-and-13-10-upgrade Wireless works fine after a reboot, but after a suspend the hardware switch (for my laptop this is f12) has no effect on the wireless, it is just permanently off, and shows that it is with a red LED. My rfkill list all reads: 0: phy0: Wireless LAN Soft blocked: no Hard blocked: yes 1: hp-wifi: Wireless LAN Soft blocked: no Hard blocked: yes Any combination with rfkill <un>block wifi doesn't work, although one time first blocking then unblocking actually turned it on again. sudo lshw -C network reads: *-network DISABLED description: Wireless interface product: AR9285 Wireless Network Adapter (PCI-Express) vendor: Qualcomm Atheros physical id: 0 bus info: pci@0000:02:00.0 logical name: wlan0 version: 01 serial: 78:e4:00:65:2e:3f width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=ath9k driverversion=3.11.0-12-generic firmware=N/A latency=0 link=no multicast=yes wireless=IEEE 802.11bgn resources: irq:17 memory:90100000-9010ffff *-network DISABLED description: Ethernet interface product: RTL8101E/RTL8102E PCI Express Fast Ethernet controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:03:00.0 logical name: eth0 version: 02 serial: c8:0a:a9:89:b4:30 size: 10Mbit/s capacity: 100Mbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix vpd bus_master cap_list rom ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=half latency=0 link=no multicast=yes port=MII speed=10Mbit/s resources: irq:42 ioport:2000(size=256) memory:90010000-90010fff memory:90000000-9000ffff memory:90020000-9002ffff Also, adding a /etc/pm/sleep.d/brcm.sh file as recommended here simply prevents the laptop from suspending at all, which of course is no good. This question has an answer urging to install the original driver, but it wasn't an "accepted answer" so I'd rather not take a chance on it. Also I'll admit I'm a bit lost on that and would like help doing so with the specific information I've given. I would be happy to provide more information, so long as you're willing to help me find it for you! This is a very annoying bug. I have a Compaq Presario CQ62. Edit. Output of lspci | grep Network: 02:00.0 Network controller: Qualcomm Atheros AR9285 Wireless Network Adapter (PCI-Express) (rev 01) Edit. This morning, I had had the laptop suspended all night, and then when I tried to awake it, it simply wouldn't. It would try, and then it would sleep again (I guess it felt a little bit like me! </badjoke>). Is it possible these problems are related? Edit. I don't have enough reputation on SU proper to post links to pastebins and other questions I've tried, so I'm putting them in comments, and of course they're available in the original question.

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• Getting error while installing mod_wsgi in centos

  - by user825904

  I have reinstalled python with enable shared [root@master mod_wsgi-3.4]# make clean rm -rf .libs rm -f mod_wsgi.o mod_wsgi.la mod_wsgi.lo mod_wsgi.slo mod_wsgi.loT rm -f config.log config.status rm -rf autom4te.cache [root@master mod_wsgi-3.4]# LD_RUN_PATH=/usr/local/lib make apxs -c -I/usr/local/include/python2.7 -DNDEBUG mod_wsgi.c -L/usr/local/lib -L/usr/local/lib/python2.7/config -lpython2.7 -lpthread -ldl -lutil -lm /usr/lib64/apr-1/build/libtool --silent --mode=compile gcc -prefer-pic -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic -Wformat-security -fno-strict-aliasing -DLINUX=2 -D_REENTRANT -D_GNU_SOURCE -pthread -I/usr/include/httpd -I/usr/include/apr-1 -I/usr/include/apr-1 -I/usr/local/include/python2.7 -DNDEBUG -c -o mod_wsgi.lo mod_wsgi.c && touch mod_wsgi.slo In file included from /usr/local/include/python2.7/Python.h:8, from mod_wsgi.c:142: /usr/local/include/python2.7/pyconfig.h:1161:1: warning: "_POSIX_C_SOURCE" redefined In file included from /usr/include/sys/types.h:26, from /usr/include/apr-1/apr-x86_64.h:127, from /usr/include/apr-1/apr.h:19, from /usr/include/httpd/ap_config.h:25, from /usr/include/httpd/httpd.h:43, from mod_wsgi.c:34: /usr/include/features.h:162:1: warning: this is the location of the previous definition In file included from /usr/local/include/python2.7/Python.h:8, from mod_wsgi.c:142: /usr/local/include/python2.7/pyconfig.h:1183:1: warning: "_XOPEN_SOURCE" redefined In file included from /usr/include/sys/types.h:26, from /usr/include/apr-1/apr-x86_64.h:127, from /usr/include/apr-1/apr.h:19, from /usr/include/httpd/ap_config.h:25, from /usr/include/httpd/httpd.h:43, from mod_wsgi.c:34: /usr/include/features.h:164:1: warning: this is the location of the previous definition mod_wsgi.c: In function ‘wsgi_server_group’: mod_wsgi.c:991: warning: unused variable ‘value’ mod_wsgi.c: In function ‘Log_isatty’: mod_wsgi.c:1665: warning: unused variable ‘result’ mod_wsgi.c: In function ‘Log_writelines’: mod_wsgi.c:1802: warning: unused variable ‘msg’ mod_wsgi.c: In function ‘Adapter_output’: mod_wsgi.c:3087: warning: unused variable ‘n’ mod_wsgi.c: In function ‘Adapter_file_wrapper’: mod_wsgi.c:4138: warning: unused variable ‘result’ mod_wsgi.c: In function ‘wsgi_python_term’: mod_wsgi.c:5850: warning: unused variable ‘tstate’ mod_wsgi.c:5849: warning: unused variable ‘interp’ mod_wsgi.c: In function ‘wsgi_python_child_init’: mod_wsgi.c:7050: warning: unused variable ‘l’ mod_wsgi.c:6948: warning: unused variable ‘interp’ mod_wsgi.c: In function ‘wsgi_add_import_script’: mod_wsgi.c:7701: warning: unused variable ‘error’ mod_wsgi.c: In function ‘wsgi_add_handler_script’: mod_wsgi.c:8179: warning: unused variable ‘dconfig’ mod_wsgi.c:8178: warning: unused variable ‘sconfig’ mod_wsgi.c: In function ‘wsgi_hook_handler’: mod_wsgi.c:9375: warning: suggest parentheses around assignment used as truth value mod_wsgi.c:9377: warning: suggest parentheses around assignment used as truth value mod_wsgi.c:9379: warning: suggest parentheses around assignment used as truth value mod_wsgi.c:9383: warning: suggest parentheses around assignment used as truth value mod_wsgi.c:9403: warning: suggest parentheses around assignment used as truth value mod_wsgi.c:9405: warning: suggest parentheses around assignment used as truth value mod_wsgi.c:9408: warning: suggest parentheses around assignment used as truth value mod_wsgi.c: In function ‘wsgi_daemon_worker’: mod_wsgi.c:10819: warning: unused variable ‘duration’ mod_wsgi.c:10818: warning: unused variable ‘start’ mod_wsgi.c: In function ‘wsgi_hook_daemon_handler’: mod_wsgi.c:13172: warning: unused variable ‘i’ mod_wsgi.c:13170: warning: unused variable ‘elts’ mod_wsgi.c:13169: warning: unused variable ‘head’ mod_wsgi.c: At top level: mod_wsgi.c:8142: warning: ‘wsgi_set_user_authoritative’ defined but not used mod_wsgi.c:15251: warning: ‘wsgi_hook_check_user_id’ defined but not used /usr/lib64/apr-1/build/libtool --silent --mode=link gcc -o mod_wsgi.la -rpath /usr/lib64/httpd/modules -module -avoid-version mod_wsgi.lo -L/usr/local/lib -L/usr/local/lib/python2.7/config -lpython2.7 -lpthread -ldl -lutil -lm

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• A gigabit network interface is CPU-limited to 25MB/s. How can I maximize the throughput?

  - by netvope

  I have a Acer Aspire R1600-U910H with a nForce gigabit network adapter. The maximum TCP throughput of it is about 25MB/s, and apparently it is limited by the single core Intel Atom 230; when the maximum throughput is reached, the CPU usage is about 50%-60%, which corresponds to full utilization considering this is a Hyper-threading enabled CPU. The same problem occurs on both Windows XP and on Ubuntu 8.04. On Windows, I have installed the latest nForce chipset driver, disabled power saving features, and enabled checksum offload. On Linux, the default driver has checksum offload enabled. There is no Linux driver available on Nvidia's website. ethtool -k eth0 shows that checksum offload is enabled: Offload parameters for eth0: rx-checksumming: on tx-checksumming: on scatter-gather: on tcp segmentation offload: on udp fragmentation offload: off generic segmentation offload: off The following is the output of powertop when the network is idle: Wakeups-from-idle per second : 61.9 interval: 10.0s no ACPI power usage estimate available Top causes for wakeups: 90.9% (101.3) <interrupt> : eth0 4.5% ( 5.0) iftop : schedule_timeout (process_timeout) 1.8% ( 2.0) <kernel core> : clocksource_register (clocksource_watchdog) 0.9% ( 1.0) dhcdbd : schedule_timeout (process_timeout) 0.5% ( 0.6) <kernel core> : neigh_table_init_no_netlink (neigh_periodic_timer) And when the maximum throughput of about 25MB/s is reached: Wakeups-from-idle per second : 11175.5 interval: 10.0s no ACPI power usage estimate available Top causes for wakeups: 99.9% (22097.4) <interrupt> : eth0 0.0% ( 5.0) iftop : schedule_timeout (process_timeout) 0.0% ( 2.0) <kernel core> : clocksource_register (clocksource_watchdog) 0.0% ( 1.0) dhcdbd : schedule_timeout (process_timeout) 0.0% ( 0.6) <kernel core> : neigh_table_init_no_netlink (neigh_periodic_timer) Notice the 20000 interrupts per second. Could this be the cause for the high CPU usage and low throughput? If so, how can I improve the situation? As a reference, the other computers in the network can usually transfer at 50+MB/s without problems. A computer with a Core 2 CPU generates only 5000 interrupts per second when it's transferring at 110MB/s. The number of interrupts is about 20 times less than the Atom system (if interrupts scale linearly with throughput.) And a minor question: How can I find out what is the driver in use for eth0?

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• Vim digraphs is not working

  - by Hauleth

  I've tried to input digraphs in Vim (without vi compatibility), and unfortunately I can't. After using ControlKP * it should input big greek pi letter. I've also tried using PBS * with :set digraph, but no success either. My gvim --version output: VIM - Vi IMproved 7.3 (2010 Aug 15, compiled Oct 23 2012 18:42:18) Included patches: 1-712 Compiled by ArchLinux Big version with GTK2 GUI. Features included (+) or not (-): +arabic +autocmd +balloon_eval +browse ++builtin_terms +byte_offset +cindent +clientserver +clipboard +cmdline_compl +cmdline_hist +cmdline_info +comments +conceal +cryptv +cscope +cursorbind +cursorshape +dialog_con_gui +diff +digraphs +dnd -ebcdic +emacs_tags +eval +ex_extra +extra_search +farsi +file_in_path +find_in_path +float +folding -footer +fork() +gettext -hangul_input +iconv +insert_expand +jumplist +keymap +langmap +libcall +linebreak +lispindent +listcmds +localmap +lua +menu +mksession +modify_fname +mouse +mouseshape +mouse_dec +mouse_gpm -mouse_jsbterm +mouse_netterm +mouse_sgr -mouse_sysmouse +mouse_urxvt +mouse_xterm +multi_byte +multi_lang -mzscheme +netbeans_intg +path_extra +perl +persistent_undo +postscript +printer -profile +python -python3 +quickfix +reltime +rightleft +ruby +scrollbind +signs +smartindent -sniff +startuptime +statusline -sun_workshop +syntax +tag_binary +tag_old_static -tag_any_white -tcl +terminfo +termresponse +textobjects +title +toolbar +user_commands +vertsplit +virtualedit +visual +visualextra +viminfo +vreplace +wildignore +wildmenu +windows +writebackup +X11 -xfontset +xim +xsmp_interact +xterm_clipboard -xterm_save system vimrc file: "/etc/vimrc" user vimrc file: "$HOME/.vimrc" user exrc file: "$HOME/.exrc" system gvimrc file: "/etc/gvimrc" user gvimrc file: "$HOME/.gvimrc" system menu file: "$VIMRUNTIME/menu.vim" fall-back for $VIM: "/usr/share/vim" Compilation: gcc -c -I. -Iproto -DHAVE_CONFIG_H -DFEAT_GUI_GTK -pthread -I/usr/include/gtk-2.0 -I/usr/lib/gtk-2.0/include -I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/pango-1.0 -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng15 -I/usr/local/include -march=x86-64 -mtune=generic -O2 -pipe -fstack-protector --param=ssp-buffer-size=4 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1 Linking: gcc -L. -Wl,-O1,--sort-common,--as-needed,-z,relro -rdynamic -Wl,-export-dynamic -Wl,-E -Wl,-rpath,/usr/lib/perl5/core_perl/CORE -Wl,-O1,--sort-common,--as-needed,-z,relro -L/usr/local/lib -Wl,--as-needed -o vim -lgtk-x11-2.0 -lgdk-x11-2.0 -latk-1.0 -lgio-2.0 -lpangoft2-1.0 -lpangocairo-1.0 -lgdk_pixbuf-2.0 -lcairo -lpango-1.0 -lfreetype -lfontconfig -lgobject-2.0 -lglib-2.0 -lSM -lICE -lXt -lX11 -lXdmcp -lSM -lICE -lm -lncurses -lnsl -lacl -lattr -lgpm -ldl -L/usr/lib -llua -Wl,-E -Wl,-rpath,/usr/lib/perl5/core_perl/CORE -Wl,-O1,--sort-common,--as-needed,-z,relro -fstack-protector -L/usr/local/lib -L/usr/lib/perl5/core_perl/CORE -lperl -lnsl -ldl -lm -lcrypt -lutil -lpthread -lc -L/usr/lib/python2.7/config -lpython2.7 -lpthread -ldl -lutil -lm -Xlinker -export-dynamic -lruby -lpthread -lrt -ldl -lcrypt -lm -L/usr/lib Can you tell me how to get my ControlK digraphs work? EDIT: Output of :verbose set enc? fenc? is: encoding=utf-8 Last set from ~/.vimrc fileencoding=

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• The Complete List of iPad Tips, Tricks, and Tutorials

  - by Ross

  The Apple iPad is the latest new toy, and we’ve put together a comprehensive list of every tip, trick, and tutorial that we could find to help you get the most out of it—and we’re even giving one away to one lucky reader. So read on! Note: We’ll be keeping this page updated as we find more great articles, so you should bookmark this page for future reference. Want Your Own iPad? How-To Geek is Giving One Away! All you have to do to enter is become a fan of our Facebook page, and we’ll pick a random fan to win the prize. Win an iPad on the How-To Geek Facebook Fan Page Disable the “clicking sound” on the iPad Keyboard Does the clicking sound when you tap the iPad keyboard bother you? Thankfully it’s easy to disable with a couple of taps. How to disable the “clicking sound” on your iPad’s keyboard Enable and add bookmarks to the Safari Bookmarks Bar on your iPad By default, Safari doesn’t display the Bookmarks Bar. This tip shows you how to change that. How to enable and add bookmarks to the Safari Bookmarks Bar on your iPad Clear the Cache, History and Cookies in Safari for the iPad You’re probably used to clearing this kind of data right from within the browser. Not so with Safari on the iPad – but here’s how you can. How to clear the cache, history and cookies in Safari for iPad How to add more Apps to your iPad Dock The iPad has four icons in its ‘dock’. Did you know it can hold 6? How to add more Apps to your iPad Dock Convert PDF files to ePub files to read on your iPad with iBooks ePub is the format that iBooks are in. So for those of you with large eBook collections in PDF, here’s how you convert them to read in iBooks. How to convert PDF files to ePub files to read on your iPad with iBooks How to force your iPad to restart Has an app caused your iPad to freeze up, and you can’t escape? This tip shows you how to force your iPad to restart. How to force your iPad to restart How to export Keynote for iPad presentations to your Mac or PC Exporting Keynote presentations from your iPad to your Mac or PC isn’t as straight forward as you might have expected. This tutorial shows you how. How to export Keynote for iPad presentations to your Mac or PC How to import presentations to Keynote on your iPad Having trouble getting your presentations onto your iPad? How to import presentations to Keynote on your iPad How to import documents to Pages on your iPad This guide shows you how to transfer documents (MS Word or Pages) from your Mac/PC to your iPad. How to import documents to Pages on your iPad How to insert photos in a Pages document using iPad and share it as a PDF Want to spice up that doc with a picture you just took? This tutorial will show you how – and how to export that document as a PDF. How to insert photos in a Pages document using iPad and share it as a PDF How to lock your iPad If you have kids or co-workers/friends who think it’s funny to mess with your iPad – lock it. How to lock your iPad How to remove the “Sent from my iPad” signature from outgoing email on your iPad Does everyone need to know you just sent that email from your iPad? Probably not. This guide shows you how to remove the “Sent from my iPad” signature and replace it with your own (or none). How to remove the “Sent from my iPad” signature from outgoing email on your iPad How To Sync Multiple Calendars to the iPad With Google Sync This tutorial will show you a workaround on how to sync multiple calendars on your iPad using Google Sync. How to Sync Multiple Calendars to the iPad With Google Sync How to determine the MAC address of your iPad If your network restricts connections via MAC address – this guide will show you how to determine what yours is. How to determine the MAC address of your iPad How to take a screenshot of your iPad Do you need to take a screenshot of your iPad? This quick tip shows you how to do just that. How to take a screenshot of your iPad How to delete apps from your iPod Touch, iPhone or iPad Anyone who had an iPod Touch or iPhone before they had an iPad won’t need this tutorial. But if you’re new to the experience, this one will help. How to delete apps from your iPod Touch, iPhone or iPad How to determine the iPad ECID on Windows and Mac iPadintosh shows us how to determine the iPad’s ECID code – something you’ll want to have come Jailbreak time. How to grab the iPad ECID in Windows or OS X iPad Apps: Twitter and social networking essentials Enggadget has you covered with reviews of the first slew of iPad specific Twitter and other social networking apps. iPad Apps: Twitter and social networking essentials What does your website look like on an iPad? iPad Peek is a web based tool that allows you to enter any given URL, and it will display that page the same way Safari on the iPad does. Great for web site owners who don’t have access to an iPad. iPadPeek Stream Music and Videos to your iPad Gizmodo reviews the iPad app StreamToMe, which allows you to stream media from your Mac to your iPad across your local network. Their feelings in a nutshell – worth the $3, but not perfect. Review: StreamToMe for the iPad Apple iPad : Change links in Google Reader to point to full HTML webpage How to change links in Safari for iPad so that Google Reader points to a full HTML webpage How to connect an iPad to your existing wireless keyboard This video will show you how to connect your iPad to a wireless keyboard if you’re having any problems – and from the sound of things, quite a few folks are. via TUAW How to get started with the iPad Mashable has a very entry-level guide that will help you set up your iPad for the first time. Mashable’s Guide to Setting up the iPad Essential iPad Apps Downloadsquad gives mini-reviews to 8 iPad apps that you should install as soon as you get your iPad. iPad App Buyers Guide: Essential Apps you should get on day one Videos: The Official iPad Guided Tours From none other than Apple! Great getting started videos for all the included iPad apps. The Official iPad Guided Tours The Official iPad Manual When you buy an iPad, you don’t get a manual. But that’s not to say there isn’t one. Apple provides a 150 guide for your iPad in PDF format. The Official iPad Manual (pdf) How to print from your iPad Sure, it’s actually just an App (PrintCentral – $9.99 USD), but as of right now, it’s the only way. PrintCentral How to make your own iPad Wallpaper A perfectly detailed tutorial on how to make your own wallpaper for your iPad. The author also provides a really nice sample wallpaper, published under the Attribution-Noncommercial 2.0 Generic license. How to make your own iPad Wallpaper Got any more tips? Share them in the comments, and we’ll update the post with the links, or just the tip itself. Similar Articles Productive Geek Tips Want an iPad? How-To Geek is Giving One Away!Why Wait? Amazing New Add-on Turns Your iPhone into an iPad! [Comic]Clear the Auto-Complete Email Address Cache in OutlookAsk the Readers: Share Your Tips for Defeating Viruses and MalwareStupid Geek Tricks: Tile or Cascade Multiple Windows in Windows 7 TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Are You Blocked On Gtalk? Find out Discover Latest Android Apps On AppBrain The Ultimate Guide For YouTube Lovers Will it Blend? iPad Edition Penolo Lets You Share Sketches On Twitter Visit Woolyss.com for Old School Games, Music and Videos

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• C# HashSet<T>

  - by Ben Griswold

  I hadn’t done much (read: anything) with the C# generic HashSet until I recently needed to produce a distinct collection.  As it turns out, HashSet<T> was the perfect tool. As the following snippet demonstrates, this collection type offers a lot: // Using HashSet<T>: // http://www.albahari.com/nutshell/ch07.aspx var letters = new HashSet<char>("the quick brown fox");   Console.WriteLine(letters.Contains('t')); // true Console.WriteLine(letters.Contains('j')); // false   foreach (char c in letters) Console.Write(c); // the quickbrownfx Console.WriteLine();   letters = new HashSet<char>("the quick brown fox"); letters.IntersectWith("aeiou"); foreach (char c in letters) Console.Write(c); // euio Console.WriteLine();   letters = new HashSet<char>("the quick brown fox"); letters.ExceptWith("aeiou"); foreach (char c in letters) Console.Write(c); // th qckbrwnfx Console.WriteLine();   letters = new HashSet<char>("the quick brown fox"); letters.SymmetricExceptWith("the lazy brown fox"); foreach (char c in letters) Console.Write(c); // quicklazy Console.WriteLine(); The MSDN documentation is a bit light on HashSet<T> documentation but if you search hard enough you can find some interesting information and benchmarks. But back to that distinct list I needed… // MSDN Add // http://msdn.microsoft.com/en-us/library/bb353005.aspx var employeeA = new Employee {Id = 1, Name = "Employee A"}; var employeeB = new Employee {Id = 2, Name = "Employee B"}; var employeeC = new Employee {Id = 3, Name = "Employee C"}; var employeeD = new Employee {Id = 4, Name = "Employee D"};   var naughty = new List<Employee> {employeeA}; var nice = new List<Employee> {employeeB, employeeC};   var employees = new HashSet<Employee>(); naughty.ForEach(x => employees.Add(x)); nice.ForEach(x => employees.Add(x));   foreach (Employee e in employees) Console.WriteLine(e); // Returns Employee A Employee B Employee C The Add Method returns true on success and, you guessed it, false if the item couldn’t be added to the collection.  I’m using the Linq ForEach syntax to add all valid items to the employees HashSet.  It works really great.  This is just a rough sample, but you may have noticed I’m using Employee, a reference type.  Most samples demonstrate the power of the HashSet with a collection of integers which is kind of cheating.  With value types you don’t have to worry about defining your own equality members.  With reference types, you do. internal class Employee {     public int Id { get; set; }     public string Name { get; set; }       public override string ToString()     {         return Name;     }          public bool Equals(Employee other)     {         if (ReferenceEquals(null, other)) return false;         if (ReferenceEquals(this, other)) return true;         return other.Id == Id;     }       public override bool Equals(object obj)     {         if (ReferenceEquals(null, obj)) return false;         if (ReferenceEquals(this, obj)) return true;         if (obj.GetType() != typeof (Employee)) return false;         return Equals((Employee) obj);     }       public override int GetHashCode()     {         return Id;     }       public static bool operator ==(Employee left, Employee right)     {         return Equals(left, right);     }       public static bool operator !=(Employee left, Employee right)     {         return !Equals(left, right);     } } Fortunately, with Resharper, it’s a snap. Click on the class name, ALT+INS and then follow with the handy dialogues. That’s it. Try out the HashSet<T>. It’s good stuff.

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• NLog Exception Details Renderer

  - by jtimperley

  Originally posted on: http://geekswithblogs.net/jtimperley/archive/2013/07/28/nlog-exception-details-renderer.aspxI recently switch from Microsoft's Enterprise Library Logging block to NLog.  In my opinion, NLog offers a simpler and much cleaner configuration section with better use of placeholders, complemented by custom variables. Despite this, I found one deficiency in my migration; I had lost the ability to simply render all details of an exception into our logs and notification emails. This is easily remedied by implementing a custom layout renderer. Start by extending 'NLog.LayoutRenderers.LayoutRenderer' and overriding the 'Append' method. using System.Text; using NLog; using NLog.Config; using NLog.LayoutRenderers;   [ThreadAgnostic] [LayoutRenderer(Name)] public class ExceptionDetailsRenderer : LayoutRenderer { public const string Name = "exceptiondetails";   protected override void Append(StringBuilder builder, LogEventInfo logEvent) { // Todo: Append details to StringBuilder } }   Now that we have a base layout renderer, we simply need to add the formatting logic to add exception details as well as inner exception details. This is done using reflection with some simple filtering for the properties that are already being rendered. I have added an additional 'Register' method, allowing the definition to be registered in code, rather than in configuration files. This complements by 'LogWrapper' class which standardizes writing log entries throughout my applications. using System; using System.Collections.Generic; using System.Linq; using System.Reflection; using System.Text; using NLog; using NLog.Config; using NLog.LayoutRenderers;   [ThreadAgnostic] [LayoutRenderer(Name)] public sealed class ExceptionDetailsRenderer : LayoutRenderer { public const string Name = "exceptiondetails"; private const string _Spacer = "======================================"; private List<string> _FilteredProperties;   private List<string> FilteredProperties { get { if (_FilteredProperties == null) { _FilteredProperties = new List<string> { "StackTrace", "HResult", "InnerException", "Data" }; }   return _FilteredProperties; } }   public bool LogNulls { get; set; }   protected override void Append(StringBuilder builder, LogEventInfo logEvent) { Append(builder, logEvent.Exception, false); }   private void Append(StringBuilder builder, Exception exception, bool isInnerException) { if (exception == null) { return; }   builder.AppendLine();   var type = exception.GetType(); if (isInnerException) { builder.Append("Inner "); }   builder.AppendLine("Exception Details:") .AppendLine(_Spacer) .Append("Exception Type: ") .AppendLine(type.ToString());   var bindingFlags = BindingFlags.Instance | BindingFlags.Public; var properties = type.GetProperties(bindingFlags); foreach (var property in properties) { var propertyName = property.Name; var isFiltered = FilteredProperties.Any(filter => String.Equals(propertyName, filter, StringComparison.InvariantCultureIgnoreCase)); if (isFiltered) { continue; }   var propertyValue = property.GetValue(exception, bindingFlags, null, null, null); if (propertyValue == null && !LogNulls) { continue; }   var valueText = propertyValue != null ? propertyValue.ToString() : "NULL"; builder.Append(propertyName) .Append(": ") .AppendLine(valueText); }   AppendStackTrace(builder, exception.StackTrace, isInnerException); Append(builder, exception.InnerException, true); }   private void AppendStackTrace(StringBuilder builder, string stackTrace, bool isInnerException) { if (String.IsNullOrEmpty(stackTrace)) { return; }   builder.AppendLine();   if (isInnerException) { builder.Append("Inner "); }   builder.AppendLine("Exception StackTrace:") .AppendLine(_Spacer) .AppendLine(stackTrace); }   public static void Register() { Type definitionType; var layoutRenderers = ConfigurationItemFactory.Default.LayoutRenderers; if (layoutRenderers.TryGetDefinition(Name, out definitionType)) { return; }   layoutRenderers.RegisterDefinition(Name, typeof(ExceptionDetailsRenderer)); LogManager.ReconfigExistingLoggers(); } } For brevity I have removed the Trace, Debug, Warn, and Fatal methods. They are modelled after the Info methods. As mentioned above, note how the log wrapper automatically registers our custom layout renderer reducing the amount of application configuration required. using System; using NLog;   public static class LogWrapper { static LogWrapper() { ExceptionDetailsRenderer.Register(); }   #region Log Methods   public static void Info(object toLog) { Log(toLog, LogLevel.Info); }   public static void Info(string messageFormat, params object[] parameters) { Log(messageFormat, parameters, LogLevel.Info); }   public static void Error(object toLog) { Log(toLog, LogLevel.Error); }   public static void Error(string message, Exception exception) { Log(message, exception, LogLevel.Error); }   private static void Log(string messageFormat, object[] parameters, LogLevel logLevel) { string message = parameters.Length == 0 ? messageFormat : string.Format(messageFormat, parameters); Log(message, (Exception)null, logLevel); }   private static void Log(object toLog, LogLevel logLevel, LogType logType = LogType.General) { if (toLog == null) { throw new ArgumentNullException("toLog"); }   if (toLog is Exception) { var exception = toLog as Exception; Log(exception.Message, exception, logLevel, logType); } else { var message = toLog.ToString(); Log(message, null, logLevel, logType); } }   private static void Log(string message, Exception exception, LogLevel logLevel, LogType logType = LogType.General) { if (exception == null && String.IsNullOrEmpty(message)) { return; }   var logger = GetLogger(logType); // Note: Using the default constructor doesn't set the current date/time var logInfo = new LogEventInfo(logLevel, logger.Name, message); logInfo.Exception = exception; logger.Log(logInfo); }   private static Logger GetLogger(LogType logType) { var loggerName = logType.ToString(); return LogManager.GetLogger(loggerName); }   #endregion   #region LogType private enum LogType { General } #endregion } The following configuration is similar to what is provided for each of my applications. The 'application' variable is all that differentiates the various applications in all of my environments, the rest has been standardized. Depending on your needs to tweak this configuration while developing and debugging, this section could easily be pushed back into code similar to the registering of our custom layout renderer.   <?xml version="1.0"?>   <configuration> <configSections> <section name="nlog" type="NLog.Config.ConfigSectionHandler, NLog"/> </configSections> <nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <variable name="application" value="Example"/> <targets> <target type="EventLog" name="EventLog" source="${application}" log="${application}" layout="${message}${onexception: ${newline}${exceptiondetails}}"/> <target type="Mail" name="Email" smtpServer="smtp.example.local" from="[email protected]" to="[email protected]" subject="(${machinename}) ${application}: ${level}" body="Machine: ${machinename}${newline}Timestamp: ${longdate}${newline}Level: ${level}${newline}Message: ${message}${onexception: ${newline}${exceptiondetails}}"/> </targets> <rules> <logger name="*" minlevel="Debug" writeTo="EventLog" /> <logger name="*" minlevel="Error" writeTo="Email" /> </rules> </nlog> </configuration>   Now go forward, create your custom exceptions without concern for including their custom properties in your exception logs and notifications.

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• Parallelism in .NET – Part 5, Partitioning of Work

  - by Reed

  When parallelizing any routine, we start by decomposing the problem.  Once the problem is understood, we need to break our work into separate tasks, so each task can be run on a different processing element.  This process is called partitioning. Partitioning our tasks is a challenging feat.  There are opposing forces at work here: too many partitions adds overhead, too few partitions leaves processors idle.  Trying to work the perfect balance between the two extremes is the goal for which we should aim.  Luckily, the Task Parallel Library automatically handles much of this process.  However, there are situations where the default partitioning may not be appropriate, and knowledge of our routines may allow us to guide the framework to making better decisions. First off, I’d like to say that this is a more advanced topic.  It is perfectly acceptable to use the parallel constructs in the framework without considering the partitioning taking place.  The default behavior in the Task Parallel Library is very well-behaved, even for unusual work loads, and should rarely be adjusted.  I have found few situations where the default partitioning behavior in the TPL is not as good or better than my own hand-written partitioning routines, and recommend using the defaults unless there is a strong, measured, and profiled reason to avoid using them.  However, understanding partitioning, and how the TPL partitions your data, helps in understanding the proper usage of the TPL. I indirectly mentioned partitioning while discussing aggregation.  Typically, our systems will have a limited number of Processing Elements (PE), which is the terminology used for hardware capable of processing a stream of instructions.  For example, in a standard Intel i7 system, there are four processor cores, each of which has two potential hardware threads due to Hyperthreading.  This gives us a total of 8 PEs – theoretically, we can have up to eight operations occurring concurrently within our system. In order to fully exploit this power, we need to partition our work into Tasks.  A task is a simple set of instructions that can be run on a PE.  Ideally, we want to have at least one task per PE in the system, since fewer tasks means that some of our processing power will be sitting idle.  A naive implementation would be to just take our data, and partition it with one element in our collection being treated as one task.  When we loop through our collection in parallel, using this approach, we’d just process one item at a time, then reuse that thread to process the next, etc.  There’s a flaw in this approach, however.  It will tend to be slower than necessary, often slower than processing the data serially. The problem is that there is overhead associated with each task.  When we take a simple foreach loop body and implement it using the TPL, we add overhead.  First, we change the body from a simple statement to a delegate, which must be invoked.  In order to invoke the delegate on a separate thread, the delegate gets added to the ThreadPool’s current work queue, and the ThreadPool must pull this off the queue, assign it to a free thread, then execute it.  If our collection had one million elements, the overhead of trying to spawn one million tasks would destroy our performance. The answer, here, is to partition our collection into groups, and have each group of elements treated as a single task.  By adding a partitioning step, we can break our total work into small enough tasks to keep our processors busy, but large enough tasks to avoid overburdening the ThreadPool.  There are two clear, opposing goals here: Always try to keep each processor working, but also try to keep the individual partitions as large as possible. When using Parallel.For, the partitioning is always handled automatically.  At first, partitioning here seems simple.  A naive implementation would merely split the total element count up by the number of PEs in the system, and assign a chunk of data to each processor.  Many hand-written partitioning schemes work in this exactly manner.  This perfectly balanced, static partitioning scheme works very well if the amount of work is constant for each element.  However, this is rarely the case.  Often, the length of time required to process an element grows as we progress through the collection, especially if we’re doing numerical computations.  In this case, the first PEs will finish early, and sit idle waiting on the last chunks to finish.  Sometimes, work can decrease as we progress, since previous computations may be used to speed up later computations.  In this situation, the first chunks will be working far longer than the last chunks.  In order to balance the workload, many implementations create many small chunks, and reuse threads.  This adds overhead, but does provide better load balancing, which in turn improves performance. The Task Parallel Library handles this more elaborately.  Chunks are determined at runtime, and start small.  They grow slowly over time, getting larger and larger.  This tends to lead to a near optimum load balancing, even in odd cases such as increasing or decreasing workloads.  Parallel.ForEach is a bit more complicated, however. When working with a generic IEnumerable<T>, the number of items required for processing is not known in advance, and must be discovered at runtime.  In addition, since we don’t have direct access to each element, the scheduler must enumerate the collection to process it.  Since IEnumerable<T> is not thread safe, it must lock on elements as it enumerates, create temporary collections for each chunk to process, and schedule this out.  By default, it uses a partitioning method similar to the one described above.  We can see this directly by looking at the Visual Partitioning sample shipped by the Task Parallel Library team, and available as part of the Samples for Parallel Programming.  When we run the sample, with four cores and the default, Load Balancing partitioning scheme, we see this: The colored bands represent each processing core.  You can see that, when we started (at the top), we begin with very small bands of color.  As the routine progresses through the Parallel.ForEach, the chunks get larger and larger (seen by larger and larger stripes). Most of the time, this is fantastic behavior, and most likely will out perform any custom written partitioning.  However, if your routine is not scaling well, it may be due to a failure in the default partitioning to handle your specific case.  With prior knowledge about your work, it may be possible to partition data more meaningfully than the default Partitioner. There is the option to use an overload of Parallel.ForEach which takes a Partitioner<T> instance.  The Partitioner<T> class is an abstract class which allows for both static and dynamic partitioning.  By overriding Partitioner<T>.SupportsDynamicPartitions, you can specify whether a dynamic approach is available.  If not, your custom Partitioner<T> subclass would override GetPartitions(int), which returns a list of IEnumerator<T> instances.  These are then used by the Parallel class to split work up amongst processors.  When dynamic partitioning is available, GetDynamicPartitions() is used, which returns an IEnumerable<T> for each partition.  If you do decide to implement your own Partitioner<T>, keep in mind the goals and tradeoffs of different partitioning strategies, and design appropriately. The Samples for Parallel Programming project includes a ChunkPartitioner class in the ParallelExtensionsExtras project.  This provides example code for implementing your own, custom allocation strategies, including a static allocator of a given chunk size.  Although implementing your own Partitioner<T> is possible, as I mentioned above, this is rarely required or useful in practice.  The default behavior of the TPL is very good, often better than any hand written partitioning strategy.

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• Parallelism in .NET – Part 18, Task Continuations with Multiple Tasks

  - by Reed

  In my introduction to Task continuations I demonstrated how the Task class provides a more expressive alternative to traditional callbacks.  Task continuations provide a much cleaner syntax to traditional callbacks, but there are other reasons to switch to using continuations… Task continuations provide a clean syntax, and a very simple, elegant means of synchronizing asynchronous method results with the user interface.  In addition, continuations provide a very simple, elegant means of working with collections of tasks. Prior to .NET 4, working with multiple related asynchronous method calls was very tricky.  If, for example, we wanted to run two asynchronous operations, followed by a single method call which we wanted to run when the first two methods completed, we’d have to program all of the handling ourselves.  We would likely need to take some approach such as using a shared callback which synchronized against a common variable, or using a WaitHandle shared within the callbacks to allow one to wait for the second.  Although this could be accomplished easily enough, it requires manually placing this handling into every algorithm which requires this form of blocking.  This is error prone, difficult, and can easily lead to subtle bugs. Similar to how the Task class static methods providing a way to block until multiple tasks have completed, TaskFactory contains static methods which allow a continuation to be scheduled upon the completion of multiple tasks: TaskFactory.ContinueWhenAll. This allows you to easily specify a single delegate to run when a collection of tasks has completed.  For example, suppose we have a class which fetches data from the network.  This can be a long running operation, and potentially fail in certain situations, such as a server being down.  As a result, we have three separate servers which we will “query” for our information.  Now, suppose we want to grab data from all three servers, and verify that the results are the same from all three. With traditional asynchronous programming in .NET, this would require using three separate callbacks, and managing the synchronization between the various operations ourselves.  The Task and TaskFactory classes simplify this for us, allowing us to write: var server1 = Task.Factory.StartNew( () => networkClass.GetResults(firstServer) ); var server2 = Task.Factory.StartNew( () => networkClass.GetResults(secondServer) ); var server3 = Task.Factory.StartNew( () => networkClass.GetResults(thirdServer) ); var result = Task.Factory.ContinueWhenAll( new[] {server1, server2, server3 }, (tasks) => { // Propogate exceptions (see below) Task.WaitAll(tasks); return this.CompareTaskResults( tasks[0].Result, tasks[1].Result, tasks[2].Result); }); .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 is clean, simple, and elegant.  The one complication is the Task.WaitAll(tasks); statement. Although the continuation will not complete until all three tasks (server1, server2, and server3) have completed, there is a potential snag.  If the networkClass.GetResults method fails, and raises an exception, we want to make sure to handle it cleanly.  By using Task.WaitAll, any exceptions raised within any of our original tasks will get wrapped into a single AggregateException by the WaitAll method, providing us a simplified means of handling the exceptions.  If we wait on the continuation, we can trap this AggregateException, and handle it cleanly.  Without this line, it’s possible that an exception could remain uncaught and unhandled by a task, which later might trigger a nasty UnobservedTaskException.  This would happen any time two of our original tasks failed. Just as we can schedule a continuation to occur when an entire collection of tasks has completed, we can just as easily setup a continuation to run when any single task within a collection completes.  If, for example, we didn’t need to compare the results of all three network locations, but only use one, we could still schedule three tasks.  We could then have our completion logic work on the first task which completed, and ignore the others.  This is done via TaskFactory.ContinueWhenAny: var server1 = Task.Factory.StartNew( () => networkClass.GetResults(firstServer) ); var server2 = Task.Factory.StartNew( () => networkClass.GetResults(secondServer) ); var server3 = Task.Factory.StartNew( () => networkClass.GetResults(thirdServer) ); var result = Task.Factory.ContinueWhenAny( new[] {server1, server2, server3 }, (firstTask) => { return this.ProcessTaskResult(firstTask.Result); }); .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; } Here, instead of working with all three tasks, we’re just using the first task which finishes.  This is very useful, as it allows us to easily work with results of multiple operations, and “throw away” the others.  However, you must take care when using ContinueWhenAny to properly handle exceptions.  At some point, you should always wait on each task (or use the Task.Result property) in order to propogate any exceptions raised from within the task.  Failing to do so can lead to an UnobservedTaskException.

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• Framework 4 Features: Summary of Security enhancements

  - by Anthony Shorten

  In the last log entry I mentioned one of the new security features in Oracle Utilities Application Framework 4.0.1. Security is one of the major "tent poles" (to borrow a phrase from Steve Jobs) in this release of the framework. There are a number of security related enhancements requested by customers and as a result of internal reviews that we have introduced. Here is a summary of some of the security enchancements we have added in this release: Security Cache Changes - Security authorization information is automatically cached on the server for performance reasons (security is checked for every single call the product makes for all modes of access). Prior to this release the cache auto-refreshed every 30 minutes (or so). This has beem made more nimble by supporting a cache refresh every minute (or so). This means authorization changes are reflected quicker than before. Business Level security - Business Services are configurable services that are based upon Application Services. Typically, the business service inherited its security profile from its parent service. Whilst this is sufficient for most needs, it is now required to further specify security on the Business Service definition itself. This will allow granular security and allow the same application service to be exposed as different Business Services with their own security. This is particularly useful when you base a Business Service on a query zone. User Propogation - As with other client server applications, the database connections are pooled and shared as needed. This means that a common database user is used to access the database from the pool to allow sharing. Unfortunently, this means that tracability at the database level is that much harder. In Oracle Utilities Application Framework V4 the end userid is now propogated to the database using the CLIENT_IDENTIFIER as part of the Oracle JDBC connection API. This not only means that the common database userid is still used but the end user is indentifiable for the duration of the database call. This can be used for monitoring or to hook into Oracle's database security products. This enhancement is only available to Oracle Database customers. Enhanced Security Definitions - Security Administrators use the product browser front end to control access rights of defined users. While this is sufficient for most sites, a new security portal has been introduced to speed up the maintenance of security information. Oracle Identity Manager Integration - With the popularity of Oracle's Identity Management Suite, the Framework now provides an integration adapter and Identity Manager Generic Transport Connector (GTC) to allow users and group membership to be provisioned to any Oracle Utilities Application Framework based product from Oracle's Identity Manager. This is also available for Oracle Utilties Application Framework V2.2 customers. Refer to My Oracle Support KBid 970785.1 - Oracle Identity Manager Integration Overview. Audit On Inquiry - Typically the configurable audit facility in the Oracle Utilities Application Framework is used to audit changes to records. In Oracle Utilities Application Framework the Business Services and Service Scripts could be configured to audit inquiries as well. Now it is possible to attach auditing capabilities to zones on the product (including base package ones). Time Zone Support - In some of the Oracle Utilities Application Framework based products, the timezone of the end user is a factor in the processing. The user object has been extended to allow the recording of time zone information for use in product functionality. JAAS Suport - Internally the Oracle Utilities Application Framework uses a number of techniques to validate and transmit security information across the architecture. These various methods have been reconciled into using Java Authentication and Authorization Services for standardized security. This is strictly an internal change with no direct on how security operates externally. JMX Based Cache Management - In the last bullet point, I mentioned extra security applied to cache management from the browser. Alternatively a JMX based interface is now provided to allow IT operations to control the cache without the browser interface. This JMX capability can be initiated from a JSR120 compliant JMX console or JMX browser. I will be writing another more detailed blog entry on the JMX enhancements as it is quite a change and an exciting direction for the product line. Data Patch Permissions - The database installer provided with the product required lower levels of security for some operations. At some sites they wanted the ability for non-DBA's to execute the utilities in a controlled fashion. The framework now allows feature configuration to allow delegation for patch execution. User Enable Support - At some sites, the use of temporary staff such as contractors is commonplace. In this scenario, temporary security setups were required and used. A potential issue has arisen when the contractor left the company. Typically the IT group would remove the contractor from the security repository to prevent login using that contractors userid but the userid could NOT be removed from the authorization model becuase of audit requirements (if any user in the product updates financials or key data their userid is recorded for audit purposes). It is now possible to effectively diable the user from the security model to prevent any use of the useridwhilst retaining audit information. These are a subset of the security changes in Oracle Utilities Application Framework. More details about the security capabilities of the product is contained in My Oracle Support KB Id 773473.1 - Oracle Utilities Application Framework Security Overview.

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• Infinite loop during A* algorithm

  - by Tashu

  The A* algorithm is used by enemies to have a path to the goal. It's working but when sometimes I placed a tower in a grid (randomly) it produces a stack overflow error. The A* algorithm would iterate the enemy and find its path and pass the list to the enemy's path. I added debug logs and the list that I'm getting it looks like it would arrive from start cell to goal cell. Here's the log - 06-19 19:26:41.982: DEBUG/findEnemyPath, enemy X:Y(4281): X2.8256836:Y3.5 06-19 19:26:41.990: DEBUG/findEnemyPath, grid X:Y(4281): X3:Y2 06-19 19:26:41.990: DEBUG/START CELL ID:(4281): 38 06-19 19:26:41.990: DEBUG/GOAL CELL ID:(4281): 47 06-19 19:26:41.990: DEBUG/Best : 38(4281): passThrough:0.0 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 38 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 38 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 38 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 38 06-19 19:26:41.990: DEBUG/Best : 39(4281): passThrough:8.875 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 39 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 39 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 39 06-19 19:26:41.990: DEBUG/Best : 40(4281): passThrough:7.9375 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 40 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 40 06-19 19:26:41.990: DEBUG/Best : 52(4281): passThrough:8.9375 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 52 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 52 06-19 19:26:41.990: DEBUG/Best : 53(4281): passThrough:7.96875 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 53 06-19 19:26:41.990: DEBUG/Best : 28(4281): passThrough:8.9375 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 28 06-19 19:26:41.990: DEBUG/Best : 65(4281): passThrough:8.984375 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 65 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 65 06-19 19:26:41.990: DEBUG/Best : 66(4281): passThrough:7.9921875 06-19 19:26:41.990: DEBUG/Neighbor's Parent:(4281): 66 06-19 19:26:42.000: DEBUG/Best : 78(4281): passThrough:8.99609375 06-19 19:26:42.000: DEBUG/Neighbor's Parent:(4281): 78 06-19 19:26:42.000: DEBUG/Best : 79(4281): passThrough:7.998046875 06-19 19:26:42.000: DEBUG/Neighbor's Parent:(4281): 79 06-19 19:26:42.000: DEBUG/Best : 80(4281): passThrough:6.9990234375 06-19 19:26:42.000: DEBUG/Neighbor's Parent:(4281): 80 06-19 19:26:42.000: DEBUG/Neighbor's Parent:(4281): 80 06-19 19:26:42.000: DEBUG/Best : 81(4281): passThrough:5.99951171875 06-19 19:26:42.000: DEBUG/Neighbor's Parent:(4281): 81 06-19 19:26:42.000: DEBUG/Neighbor's Parent:(4281): 81 06-19 19:26:42.000: DEBUG/Best : 82(4281): passThrough:4.999755859375 06-19 19:26:42.000: DEBUG/Neighbor's Parent:(4281): 82 06-19 19:26:42.000: DEBUG/Neighbor's Parent:(4281): 82 06-19 19:26:42.000: DEBUG/Best : 83(4281): passThrough:3.9998779296875 06-19 19:26:42.000: DEBUG/Neighbor's Parent:(4281): 83 06-19 19:26:42.000: DEBUG/Best : 71(4281): passThrough:2.99993896484375 06-19 19:26:42.000: DEBUG/Neighbor's Parent:(4281): 71 06-19 19:26:42.000: DEBUG/Best : 59(4281): passThrough:1.99951171875 06-19 19:26:42.000: DEBUG/Neighbor's Parent:(4281): 59 06-19 19:26:42.000: DEBUG/Neighbor's Parent:(4281): 59 06-19 19:26:42.000: DEBUG/Neighbor's Parent:(4281): 59 06-19 19:26:42.000: DEBUG/Best : 47(4281): passThrough:0.99951171875 Then, the goal cell would be iterating its parent till start cell to break off the loop. private void populateBestList(Cell cell, List<Cell> bestList) { bestList.add(cell); if (cell.parent.start == false) { Log.d("ID:", ""+cell.id); Log.d("ParentID:", ""+cell.parent.id); populateBestList(cell.parent, bestList); } return; } The log with error above would show like this - 06-19 19:26:42.010: DEBUG/ID:(4281): 47 06-19 19:26:42.010: DEBUG/ParentID:(4281): 59 06-19 19:26:42.010: DEBUG/ID:(4281): 59 06-19 19:26:42.010: DEBUG/ParentID:(4281): 71 06-19 19:26:42.010: DEBUG/ID:(4281): 71 06-19 19:26:42.010: DEBUG/ParentID:(4281): 59 06-19 19:26:42.010: DEBUG/ID:(4281): 59 06-19 19:26:42.010: DEBUG/ParentID:(4281): 71 06-19 19:26:42.010: DEBUG/ID:(4281): 71 71 and 59 would switch over and goes on. I thought the grid is the issue due to the fact that enemies are using the single grid so I make the parent, start, and goal clear before starting the A* algorithm for an enemy. for(int i = 0; i < GRID_HEIGHT; i++) { for(int j = 0; j < GRID_WIDTH; j++) { grid[i][j].parent = null; grid[i][j].start = false; grid[i][j].goal = false; } } That didn't work. I thought it might be something related to this code, but not sure if I'm on right track - neighbor.parent = best; openList.remove(neighbor); closedList.remove(neighbor); openList.add(0, neighbor); Here's the code of the A* algorithm - private List<Cell> findEnemyPath(Enemy enemy) { for(int i = 0; i < GRID_HEIGHT; i++) { for(int j = 0; j < GRID_WIDTH; j++) { grid[i][j].parent = null; grid[i][j].start = false; grid[i][j].goal = false; } } List<Cell> openList = new ArrayList<Cell>(); List<Cell> closedList = new ArrayList<Cell>(); List<Cell> bestList = new ArrayList<Cell>(); int width = (int)Math.floor(enemy.position.x); int height = (int)Math.floor(enemy.position.y); width = (width < 0) ? 0 : width; height = (height < 0) ? 0 : height; Log.d("findEnemyPath, enemy X:Y", "X"+enemy.position.x+":"+"Y"+enemy.position.y); Log.d("findEnemyPath, grid X:Y", "X"+height+":"+"Y"+width); Cell start = grid[height][width]; Cell goal = grid[ENEMY_GOAL_HEIGHT][ENEMY_GOAL_WIDTH]; if(start.id != goal.id) { Log.d("START CELL ID: ", ""+start.id); Log.d("GOAL CELL ID: ", ""+goal.id); //Log.d("findEnemyPath, grid X:Y", "X"+start.position.x+":"+"Y"+start.position.y); start.start = true; goal.goal = true; openList.add(start); while(openList.size() > 0) { Cell best = findBestPassThrough(openList, goal); //Log.d("ID:", ""+best.id); openList.remove(best); closedList.add(best); if (best.goal) { System.out.println("Found Goal"); System.out.println(bestList.size()); populateBestList(goal, bestList); /* for(Cell cell : bestList) { Log.d("ID:", ""+cell.id); Log.d("ParentID:", ""+cell.parent.id); } */ Collections.reverse(bestList); Cell exit = new Cell(13.5f, 3.5f, 1, 1); exit.isExit = true; bestList.add(exit); //Log.d("PathList", "Enemy ID : " + enemy.id); return bestList; } else { List<Cell> neighbors = getNeighbors(best); for (Cell neighbor : neighbors) { if(neighbor.isTower) { continue; } if (openList.contains(neighbor)) { Cell tmpCell = new Cell(neighbor.position.x, neighbor.position.y, 1, 1); tmpCell.parent = best; if (tmpCell.getPassThrough(goal) >= neighbor.getPassThrough(goal)) { continue; } } if (closedList.contains(neighbor)) { Cell tmpCell = new Cell(neighbor.position.x, neighbor.position.y, 1, 1); tmpCell.parent = best; if (tmpCell.getPassThrough(goal) >= neighbor.getPassThrough(goal)) { continue; } } Log.d("Neighbor's Parent: ", ""+best.id); neighbor.parent = best; openList.remove(neighbor); closedList.remove(neighbor); openList.add(0, neighbor); } } } } Log.d("Cannot find a path", ""); return null; }

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• MySQL 5.5 - Lost connection to MySQL server during query

  - by bully

  I have an Ubuntu 12.04 LTS server running at a german hoster (virtualized system). # uname -a Linux ... 3.2.0-27-generic #43-Ubuntu SMP Fri Jul 6 14:25:57 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux I want to migrate a Web CMS system, called Contao. It's not my first migration, but my first migration having connection issues with mysql. Migration went successfully, I have the same Contao version running (it's more or less just copy / paste). For the database behind, I did: apt-get install mysql-server phpmyadmin I set a root password and added a user for the CMS which has enough rights on its own database (and only its database) for doing the stuff it has to do. Data import via phpmyadmin worked just fine. I can access the backend of the CMS (which needs to deal with the database already). If I try to access the frontend now, I get the following error: Fatal error: Uncaught exception Exception with message Query error: Lost connection to MySQL server during query (<query statement here, nothing special, just a select>) thrown in /var/www/system/libraries/Database.php on line 686 (Keep in mind: I can access mysql with phpmyadmin and through the backend, working like a charme, it's just the frontend call causing errors). If I spam F5 in my browser I can sometimes even kill the mysql deamon. If I run # mysqld --log-warnings=2 I get this: ... 120921 7:57:31 [Note] mysqld: ready for connections. Version: '5.5.24-0ubuntu0.12.04.1' socket: '/var/run/mysqld/mysqld.sock' port: 3306 (Ubuntu) 05:57:37 UTC - mysqld got signal 4 ; 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 = 346679 K bytes of memory Hope that's ok; if not, decrease some variables in the equation. Thread pointer: 0x7f1485db3b20 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 = 7f1480041e60 thread_stack 0x30000 mysqld(my_print_stacktrace+0x29)[0x7f1483b96459] mysqld(handle_fatal_signal+0x483)[0x7f1483a5c1d3] /lib/x86_64-linux-gnu/libpthread.so.0(+0xfcb0)[0x7f1482797cb0] /lib/x86_64-linux-gnu/libm.so.6(+0x42e11)[0x7f14821cae11] mysqld(_ZN10SQL_SELECT17test_quick_selectEP3THD6BitmapILj64EEyyb+0x1368)[0x7f1483b26cb8] mysqld(+0x33116a)[0x7f148397916a] mysqld(_ZN4JOIN8optimizeEv+0x558)[0x7f148397d3e8] mysqld(_Z12mysql_selectP3THDPPP4ItemP10TABLE_LISTjR4ListIS1_ES2_jP8st_orderSB_S2_SB_yP13select_resultP18st_select_lex_unitP13st_select_lex+0xdd)[0x7f148397fd7d] mysqld(_Z13handle_selectP3THDP3LEXP13select_resultm+0x17c)[0x7f1483985d2c] mysqld(+0x2f4524)[0x7f148393c524] mysqld(_Z21mysql_execute_commandP3THD+0x293e)[0x7f14839451de] mysqld(_Z11mysql_parseP3THDPcjP12Parser_state+0x10f)[0x7f1483948bef] mysqld(_Z16dispatch_command19enum_server_commandP3THDPcj+0x1365)[0x7f148394a025] mysqld(_Z24do_handle_one_connectionP3THD+0x1bd)[0x7f14839ec7cd] mysqld(handle_one_connection+0x50)[0x7f14839ec830] /lib/x86_64-linux-gnu/libpthread.so.0(+0x7e9a)[0x7f148278fe9a] /lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f1481eba4bd] Trying to get some variables. Some pointers may be invalid and cause the dump to abort. Query (7f1464004b60): is an invalid pointer Connection ID (thread ID): 1 Status: NOT_KILLED From /var/log/syslog: Sep 21 07:17:01 s16477249 CRON[23855]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly) Sep 21 07:18:51 s16477249 kernel: [231923.349159] type=1400 audit(1348204731.333:70): apparmor="STATUS" operation="profile_replace" name="/usr/sbin/mysqld" pid=23946 comm="apparmor_parser" Sep 21 07:18:53 s16477249 /etc/mysql/debian-start[23990]: Upgrading MySQL tables if necessary. Sep 21 07:18:53 s16477249 /etc/mysql/debian-start[23993]: /usr/bin/mysql_upgrade: the '--basedir' option is always ignored Sep 21 07:18:53 s16477249 /etc/mysql/debian-start[23993]: Looking for 'mysql' as: /usr/bin/mysql Sep 21 07:18:53 s16477249 /etc/mysql/debian-start[23993]: Looking for 'mysqlcheck' as: /usr/bin/mysqlcheck Sep 21 07:18:53 s16477249 /etc/mysql/debian-start[23993]: This installation of MySQL is already upgraded to 5.5.24, use --force if you still need to run mysql_upgrade Sep 21 07:18:53 s16477249 /etc/mysql/debian-start[24004]: Checking for insecure root accounts. Sep 21 07:18:53 s16477249 /etc/mysql/debian-start[24009]: Triggering myisam-recover for all MyISAM tables I'm using MyISAM tables all over, nothing with InnoDB there. Starting / stopping mysql is done via sudo service mysql start sudo service mysql stop After using google a little bit, I experimented a little bit with timeouts, correct socket path in the /etc/mysql/my.cnf file, but nothing helped. There are some old (from 2008) Gentoo bugs, where re-compiling just solved the problem. I already re-installed mysql via: sudo apt-get remove mysql-server mysql-common sudo apt-get autoremove sudo apt-get install mysql-server without any results. This is the first time I'm running into this problem, and I'm not very experienced with this kind of mysql 'administration'. So mainly, I want to know if anyone of you could help me out please :) Is it a mysql bug? Is something broken in the Ubuntu repositories? Is this one of those misterious 'use-tcp-connection-instead-of-socket-stuff-because-there-are-problems-on-virtualized-machines-with-sockets'-problem? Or am I completly on the wrong way and I just miss-configured something? Remember, phpmyadmin and access to the backend (which uses the database, too) is just fine. Maybe something with Apache? What can I do? Any help is appreciated, so thanks in advance :)

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• Parallelism in .NET – Part 6, Declarative Data Parallelism

  - by Reed

  When working with a problem that can be decomposed by data, we have a collection, and some operation being performed upon the collection.  I’ve demonstrated how this can be parallelized using the Task Parallel Library and imperative programming using imperative data parallelism via the Parallel class.  While this provides a huge step forward in terms of power and capabilities, in many cases, special care must still be given for relative common scenarios. C# 3.0 and Visual Basic 9.0 introduced a new, declarative programming model to .NET via the LINQ Project.  When working with collections, we can now write software that describes what we want to occur without having to explicitly state how the program should accomplish the task.  By taking advantage of LINQ, many operations become much shorter, more elegant, and easier to understand and maintain.  Version 4.0 of the .NET framework extends this concept into the parallel computation space by introducing Parallel LINQ. Before we delve into PLINQ, let’s begin with a short discussion of LINQ.  LINQ, the extensions to the .NET Framework which implement language integrated query, set, and transform operations, is implemented in many flavors.  For our purposes, we are interested in LINQ to Objects.  When dealing with parallelizing a routine, we typically are dealing with in-memory data storage.  More data-access oriented LINQ variants, such as LINQ to SQL and LINQ to Entities in the Entity Framework fall outside of our concern, since the parallelism there is the concern of the data base engine processing the query itself. LINQ (LINQ to Objects in particular) works by implementing a series of extension methods, most of which work on IEnumerable<T>.  The language enhancements use these extension methods to create a very concise, readable alternative to using traditional foreach statement.  For example, let’s revisit our minimum aggregation routine we wrote in Part 4: 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; } Here, we’re doing a very simple computation, but writing this in an imperative style.  This can be loosely translated to English as: Create a very large number, and save it in min Loop through each item in the collection. For every item: Perform some computation, and save the result If the computation is less than min, set min to the computation Although this is fairly easy to follow, it’s quite a few lines of code, and it requires us to read through the code, step by step, line by line, in order to understand the intention of the developer. We can rework this same statement, using LINQ: double min = collection.Min(item => item.PerformComputation()); Here, we’re after the same information.  However, this is written using a declarative programming style.  When we see this code, we’d naturally translate this to English as: Save the Min value of collection, determined via calling item.PerformComputation() That’s it – instead of multiple logical steps, we have one single, declarative request.  This makes the developer’s intentions very clear, and very easy to follow.  The system is free to implement this using whatever method required. Parallel LINQ (PLINQ) extends LINQ to Objects to support parallel operations.  This is a perfect fit in many cases when you have a problem that can be decomposed by data.  To show this, let’s again refer to our minimum aggregation routine from Part 4, but this time, let’s review our final, parallelized version: // 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); } ); Here, we’re doing the same computation as above, but fully parallelized.  Describing this in English becomes quite a feat: Create a very large number, and save it in min Create a temporary object we can use for locking Call Parallel.ForEach, specifying three delegates For the first delegate: Initialize a local variable to hold the local state to a very large number For the second delegate: For each item in the collection, perform some computation, save the result If the result is less than our local state, save the result in local state For the final delegate: Take a lock on our temporary object to protect our min variable Save the min of our min and local state variables Although this solves our problem, and does it in a very efficient way, we’ve created a set of code that is quite a bit more difficult to understand and maintain. PLINQ provides us with a very nice alternative.  In order to use PLINQ, we need to learn one new extension method that works on IEnumerable<T> – ParallelEnumerable.AsParallel(). That’s all we need to learn in order to use PLINQ: one single method.  We can write our minimum aggregation in PLINQ very simply: double min = collection.AsParallel().Min(item => item.PerformComputation()); By simply adding “.AsParallel()” to our LINQ to Objects query, we converted this to using PLINQ and running this computation in parallel!  This can be loosely translated into English easily, as well: Process the collection in parallel Get the Minimum value, determined by calling PerformComputation on each item Here, our intention is very clear and easy to understand.  We just want to perform the same operation we did in serial, but run it “as parallel”.  PLINQ completely extends LINQ to Objects: the entire functionality of LINQ to Objects is available.  By simply adding a call to AsParallel(), we can specify that a collection should be processed in parallel.  This is simple, safe, and incredibly useful.

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