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  • How to looking for open vacancies [closed]

    - by Olexander Honcharuk
    Hi everyone, In the nearest future I'll end university with master degree in computer science. I wanna work abrooad after that. Could you please advise me sites, rss feeds where I can found info about open vacancies and job suggestions. Many thanks. You're welcome send me an email to ohoncharuk[at]hotmail.com

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  • else or return?

    - by Ram
    Which one out of following two is best wrt to performance and standard practice. How does .NET internally handles these two code snippets? Code1 If(result) { process1(); } else { process2(); } Or Code 2 If(result) { process1(); return; } process2();

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  • C compiler producing lightweight executeables

    - by samuel
    I'm currently using MSVC for C++ but as I'm switching to C to write a very performance-intensive program (interpreter) I have to search for a fitting C compiler. I've looked at some binaries produced by Turbo-C and even if its old they seem pretty straigthforward and optimized. Now I don't know what the best compiler for building an interpreter is, but maybe you can help me. I've considered GCC but as I don't know much about it, I can't be really sure.

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  • Why do GPUs overheat?

    - by JAD
    About a year ago, I added a 9800GT (1 GB version) and a Corsair CX500 PSU to an HP M8000N computer. A few weeks ago, the HDD overheated and I decided to transfer the GPU & PSU to a new build, which consists of: i3 @ 3.3Ghz Gigabyte H61 Micro ATX Mobo 4GB RAM 500GB WD HDD DVD RW Drive Cooler Master Elite 430 Tower Once I had Win7 up and running, I installed all the essential drivers that came with the Gigabyte Mobo CD. However, whenever I tried installing the Graphics Media Accelerator driver, the computer would crash and enter an endless boot sequence on the next startup. I skipped installing this driver and installed the CD driver for the 9800GT, which by now is a year old. Everything was working fine, WEI rated my GPU at 6.6 graphics & aero performance. However, after updating my Nvidia drivers to the latest, the WEI dropped my rating to 3.3 for Aero, and 4.7 for graphics performance. Just to make sure that everything was ok, I ran Bad Company 2 on medium settings. The first few minutes ran just fine at a smooth framerate, so I dismissed this as Windows being Windows. About 6 hours later, I ran BC2 again. This time I averaged anywhere from 2-5 FPS. I checked the GPU temperature through GPU-Z, and it came back as 120C. The problem with this, is that the computer was on for six hours up to that point. Wouldn't the card have experienced a reactor core meltdown a lot sooner than that? Granted, the computer was "sleeping" some of the time, but still... The next day I took out a temperature gun and ran some tests. I would point the laser at a very specific area on the reverse side of the card (not the fan or "front"), and compare the temp reading with GPU-Z. After leaving the system on idle on idle for a few minutes, I ran BC2 twice. Here are the results: GPU-Z Reading / Temp Gun Reading / Time Null / 22.3°C / Comp is Off 53°C / 33.5°C / 1:49 78°C / 46°C / 1:53 - (First BC2 run; good framerate) 102°C / 64.6°C / 2:01 - (System is again on idle) 113°C / 64.8°C / 2:10 119°C / 71.8°C / 2:17 - (Second BC2 run; poor framerate) I should also mention that I also took a temp recording of another part of the GPU from 2:01-2:17. The temp in this area jumped from 75°C to 82.9°C in that time frame. This pretty much confirms that GPU-Z is reporting the temperature accurately, and the card is overheating. But I'd like to know why; the cars is doing nothing and still the temperature climbs at a steady rate. I thoroughly cleaned the GPU and PSU when I salvaged them from the old HP M8000N computer with a can of compressed air, dust cant be the issue. Similarly, the rest of the computer is brand new. I installed various Nvidia drivers, but no luck. It seems strange to me that a year-old card is suddenly failing on me; aren't they supposed to last at least two years? Could this be a driver issue? Is the motherboard faulty? Could the PSU be overfeeding the card on voltage? Neither case seems likely, as the CPU, RAM and otherwise the rest of the comp has worked flawlessly and has stayed well within respectable temp ranges (the i3 lingers around 50C, the HDD stays at 30C, so does the PSU). How can I pinpoint the issue?

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  • SATA drive problems with two SIL RAID cards

    - by Jon Topper
    I've just put a second SiI 3114 SATARaid card in my home server so that I could add another pair of SATA drives and increase my storage space. Annoyingly, it doesn't seem to work: [ 32.816030] ata5: lost interrupt (Status 0x0) [ 32.816072] ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen [ 32.816091] ata5.00: cmd c8/00:08:00:00:00/00:00:00:00:00/e0 tag 0 dma 4096 in [ 32.816094] res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout) [ 32.816101] ata5.00: status: { DRDY } [ 32.816117] ata5: hard resetting link [ 33.136082] ata5: SATA link down (SStatus 0 SControl 0) [ 36.060940] irq 18: nobody cared (try booting with the "irqpoll" option) [ 36.060949] Pid: 0, comm: swapper Not tainted 2.6.31-20-generic #58-Ubuntu [ 36.060954] Call Trace: [ 36.060977] [] ? printk+0x18/0x1c [ 36.060997] [] __report_bad_irq+0x27/0x90 [ 36.061005] [] note_interrupt+0x150/0x190 [ 36.061011] [] handle_fasteoi_irq+0xac/0xd0 [ 36.061023] [] handle_irq+0x18/0x30 [ 36.061029] [] do_IRQ+0x47/0xc0 [ 36.061042] [] ? irq_exit+0x50/0x70 [ 36.061058] [] ? smp_apic_timer_interrupt+0x57/0x90 [ 36.061065] [] common_interrupt+0x30/0x40 [ 36.061075] [] ? native_safe_halt+0x5/0x10 [ 36.061082] [] default_idle+0x46/0xd0 [ 36.061088] [] cpu_idle+0x8c/0xd0 [ 36.061103] [] rest_init+0x55/0x60 [ 36.061111] [] start_kernel+0x2e6/0x2ec [ 36.061117] [] ? unknown_bootoption+0x0/0x19e [ 36.061133] [] i386_start_kernel+0x7c/0x83 [ 36.061137] handlers: [ 36.061139] [] (sil_interrupt+0x0/0xb0) [ 36.061151] Disabling IRQ #18 [ 38.136014] ata5: hard resetting link [ 38.456022] ata5: SATA link down (SStatus 0 SControl 0) [ 43.456013] ata5: hard resetting link [ 43.776022] ata5: SATA link down (SStatus 0 SControl 0) [ 43.776035] ata5.00: disabled [ 43.776055] ata5.00: device reported invalid CHS sector 0 [ 43.776074] sd 4:0:0:0: [sde] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE [ 43.776082] sd 4:0:0:0: [sde] Sense Key : Aborted Command [current] [descriptor] [ 43.776092] Descriptor sense data with sense descriptors (in hex): [ 43.776097] 72 0b 00 00 00 00 00 0c 00 0a 80 00 00 00 00 00 [ 43.776112] 00 00 00 00 [ 43.776118] sd 4:0:0:0: [sde] Add. Sense: No additional sense information [ 43.776127] end_request: I/O error, dev sde, sector 0 [ 43.776136] Buffer I/O error on device sde, logical block 0 [ 43.776170] ata5: EH complete [ 43.776187] ata5.00: detaching (SCSI 4:0:0:0) root@core:~# cat /proc/interrupts CPU0 0: 47 IO-APIC-edge timer 1: 8 IO-APIC-edge i8042 6: 3 IO-APIC-edge floppy 7: 0 IO-APIC-edge parport0 8: 0 IO-APIC-edge rtc0 9: 0 IO-APIC-fasteoi acpi 14: 53069 IO-APIC-edge pata_sis 15: 53004 IO-APIC-edge pata_sis 17: 112265 IO-APIC-fasteoi sata_sil 18: 200002 IO-APIC-fasteoi sata_sil, SiS SI7012 19: 111140 IO-APIC-fasteoi eth0 20: 0 IO-APIC-fasteoi ohci_hcd:usb2 21: 0 IO-APIC-fasteoi ohci_hcd:usb3 23: 0 IO-APIC-fasteoi ehci_hcd:usb1 NMI: 0 Non-maskable interrupts LOC: 6650492 Local timer interrupts SPU: 0 Spurious interrupts CNT: 0 Performance counter interrupts PND: 0 Performance pending work RES: 0 Rescheduling interrupts CAL: 0 Function call interrupts TLB: 0 TLB shootdowns TRM: 0 Thermal event interrupts THR: 0 Threshold APIC interrupts MCE: 0 Machine check exceptions MCP: 160 Machine check polls ERR: 0 MIS: 0 root@core:~# lspci | grep Raid 00:09.0 RAID bus controller: Silicon Image, Inc. SiI 3114 [SATALink/SATARaid] Serial ATA Controller (rev 02) 00:0a.0 RAID bus controller: Silicon Image, Inc. SiI 3114 [SATALink/SATARaid] Serial ATA Controller (rev 02) root@core:~# lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 9.10 Release: 9.10 Codename: karmic root@core:~# uname -a Linux core.topper.me.uk 2.6.31-20-generic #58-Ubuntu SMP Fri Mar 12 05:23:09 UTC 2010 i686 GNU/Linux I've tried a combination of different kernel options (irqpoll, noapic, noacpi, pci=noapic) all to no avail. Does anyone have any bright ideas about how I can go about making this work? Swapping PCI cards around isn't an option as there are only two slots in this motherboard (an ASRock K7S41GX). The BIOS doesn't look to have too much in the way of configuration options regarding IRQ usage. Plan B is to ditch this server completely and buy a new QNAP for these drives to go in, but I was hoping to avoid doing this right now.

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  • cron.daily not running at the time it should?

    - by Mariano Martinez Peck
    My /etc/cron.daily scripts seem to be executing far later from what I understand they should. I am in Ubuntu and anacron is installed. If I do a sudo cat /var/log/syslog | grep cron I get something like: Aug 23 01:17:01 mymachine CRON[25171]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly) Aug 23 02:17:01 mymachine CRON[25588]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly) Aug 23 03:17:01 mymachine CRON[26026]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly) Aug 23 03:25:01 mymachine CRON[30320]: (root) CMD (test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )) Aug 23 04:17:01 mymachine CRON[26363]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly) Aug 23 05:17:01 mymachine CRON[26770]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly) Aug 23 06:17:01 mymachine CRON[27168]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly) Aug 23 07:17:01 mymachine CRON[27547]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly) Aug 23 07:30:01 mymachine CRON[2249]: (root) CMD (start -q anacron || :) Aug 23 07:30:02 mymachine anacron[2252]: Anacron 2.3 started on 2014-08-23 Aug 23 07:30:02 mymachine anacron[2252]: Will run job `cron.daily' in 5 min. Aug 23 07:30:02 mymachine anacron[2252]: Jobs will be executed sequentially Aug 23 07:35:02 mymachine anacron[2252]: Job `cron.daily' started As you can see, at 3:25 it tried to do something. But the cron.daily execution started really at 7:35. My /etc/crontab is: # /etc/crontab: system-wide crontab # Unlike any other crontab you don't have to run the `crontab' # command to install the new version when you edit this file # and files in /etc/cron.d. These files also have username fields, # that none of the other crontabs do. SHELL=/bin/sh PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin # m h dom mon dow user command 17 * * * * root cd / && run-parts --report /etc/cron.hourly 25 3 * * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily ) 47 6 * * 7 root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly ) 52 6 1 * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly ) # From what I understand, daily scripts are indeed for 3:25. My /etc/anacrontab is: # /etc/anacrontab: configuration file for anacron # See anacron(8) and anacrontab(5) for details. SHELL=/bin/sh PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin HOME=/root LOGNAME=root # These replace cron's entries 1 5 cron.daily run-parts --report /etc/cron.daily 7 10 cron.weekly run-parts --report /etc/cron.weekly @monthly 15 cron.monthly run-parts --report /etc/cron.monthly So...does someone know why my cron started to do something at 3:25 but then really start the jobs at 7:35? Also..as you can see in the log, hourly jobs are being executed at correct time: hour and 17 minutes, which is exactly what I have in /etc/crontab Finally, from the logs, it seems my daily jobs are being actually run by anacron rather than cron? So cron finds nothing to run (at 3:25) and then anacron runs the jobs at 7:35? If true, how can I fix this? Thanks in advance,

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  • Using Upstart to manage Unicorn w/ rbenv + bundler binstubs w/ ruby-local-exec shebang

    - by codykrieger
    Alright, this is melting my brain. It might have something to do with the fact that I don't understand Upstart as well as I should. Sorry in advance for the long question. I'm trying to use Upstart to manage a Rails app's Unicorn master process. Here is my current /etc/init/app.conf: description "app" start on runlevel [2] stop on runlevel [016] console owner # expect daemon script APP_ROOT=/home/deploy/app PATH=/home/deploy/.rbenv/shims:/home/deploy/.rbenv/bin:$PATH $APP_ROOT/bin/unicorn -c $APP_ROOT/config/unicorn.rb -E production # >> /tmp/upstart.log 2>&1 end script # respawn That works just fine - the Unicorns start up great. What's not great is that the PID detected is not of the Unicorn master, it's of an sh process. That in and of itself isn't so bad, either - if I wasn't using the automagical Unicorn zero-downtime deployment strategy. Because shortly after I send -USR2 to my Unicorn master, a new master spawns up, and the old one dies...and so does the sh process. So Upstart thinks my job has died, and I can no longer restart it with restart or stop it with stop if I want. I've played around with the config file, trying to add -D to the Unicorn line (like this: $APP_ROOT/bin/unicorn -c $APP_ROOT/config/unicorn.rb -E production -D) to daemonize Unicorn, and I added the expect daemon line, but that didn't work either. I've tried expect fork as well. Various combinations of all of those things can cause start and stop to hang, and then Upstart gets really confused about the state of the job. Then I have to restart the machine to fix it. I think Upstart is having problems detecting when/if Unicorn is forking because I'm using rbenv + the ruby-local-exec shebang in my $APP_ROOT/bin/unicorn script. Here it is: #!/usr/bin/env ruby-local-exec # # This file was generated by Bundler. # # The application 'unicorn' is installed as part of a gem, and # this file is here to facilitate running it. # require 'pathname' ENV['BUNDLE_GEMFILE'] ||= File.expand_path("../../Gemfile", Pathname.new(__FILE__).realpath) require 'rubygems' require 'bundler/setup' load Gem.bin_path('unicorn', 'unicorn') Additionally, the ruby-local-exec script looks like this: #!/usr/bin/env bash # # `ruby-local-exec` is a drop-in replacement for the standard Ruby # shebang line: # # #!/usr/bin/env ruby-local-exec # # Use it for scripts inside a project with an `.rbenv-version` # file. When you run the scripts, they'll use the project-specified # Ruby version, regardless of what directory they're run from. Useful # for e.g. running project tasks in cron scripts without needing to # `cd` into the project first. set -e export RBENV_DIR="${1%/*}" exec ruby "$@" So there's an exec in there that I'm worried about. It fires up a Ruby process, which fires up Unicorn, which may or may not daemonize itself, which all happens from an sh process in the first place...which makes me seriously doubt the ability of Upstart to track all of this nonsense. Is what I'm trying to do even possible? From what I understand, the expect stanza in Upstart can only be told (via daemon or fork) to expect a maximum of two forks.

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  • What Apache/PHP configurations do you know and how good are they?

    - by FractalizeR
    Hello. I wanted to ask you about PHP/Apache configuration methods you know, their pros and cons. I will start myself: ---------------- PHP as Apache module---------------- Pros: good speed since you don't need to start exe every time especially in mpm-worker mode. You can also use various PHP accelerators in this mode like APC or eAccelerator. Cons: if you are running apache in mpm-worker mode, you may face stability issues because every glitch in any php script will lead to unstability to the whole thread pool of that apache process. Also in this mode all scripts are executed on behalf of apache user. This is bad for security. mpm-worker configuration requires PHP compiled in thread-safe mode. At least CentOS and RedHat default repositories doesn't have thread-safe PHP version so on these OSes you need to compile at least PHP yourself (there is a way to activate worker mpm on Apache). The use of thread-safe PHP binaries is considered experimental and unstable. Plus, many PHP extensions does not support thread-safe mode or were not well-tested in thread-safe mode. ---------------- PHP as CGI ---------------- This seems to be the slowest default configuration which seems to be a "con" itself ;) ---------------- PHP as CGI via mod_suphp ---------------- Pros: suphp allows you to execute php scipts on behalf of the script file owner. This way you can securely separate different sites on the same machine. Also, suphp allows to use different php.ini files per virtual host. Cons: PHP in CGI mode means less performance. In this mode you can't use php accelerators like APC because each time new process is spawned to handle script rendering the cache of previous process useless. BTW, do you know the way to apply some accelerator in this config? I heard something about using shm for php bytecode cache. Also, you cannot configure PHP via .htaccess files in this mode. You will need to install PECL htscanner for this if you need to set various per-script options via .htaccess (php_value / php_flag directives) ---------------- PHP as CGI via suexec ---------------- This configuration looks the same as with suphp, but I heard, that it's slower and less safe. Almost same pros and cons apply. ---------------- PHP as FastCGI ---------------- Pros: FastCGI standard allows single php process to handle several scripts before php process is killed. This way you gain performance since no need to spin up new php process for each script. You can also use PHP accelerators in this configuration (see cons section for comment). Also, FCGI almost like suphp also allows php processes to be executed on behalf of some user. mod_fcgid seems to have the most complete fcgi support and flexibility for apache. Cons: The use of php accelerator in fastcgi mode will lead to high memory consumption because each PHP process will have his own bytecode cache (unless there is some accelerator that can use shared memory for bytecode cache. Is there such?). FastCGI is also a little bit complex to configure. You need to create various configuration files and make some configuration modifications. It seems, that fastcgi is the most stable, secure, fast and flexible PHP configuration, however, a bit difficult to be configured. But, may be, I missed something? Comments are welcome!

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  • register_globals error in php

    - by user145862
    I was stuck up with the error directive 'register_globals' is no longer available in PHP in unknown on line 0 when tried to check the php version using "php -v" after enabling register_globals in php.ini file. I am not getting any php version info by doing so. Instead it throws the above mentioned error.After turning off this option, php info works quite well. It is very essential for me to have register_globals to be turned on.How can I have this corrected. my php.ini is as follows: ; Default Value: None ; Development Value: "GP" ; Production Value: "GP" ; http://php.net/request-order request_order = "GP" ; Whether or not to register the EGPCS variables as global variables. You may ; want to turn this off if you don't want to clutter your scripts' global scope ; with user data. ; You should do your best to write your scripts so that they do not require ; register_globals to be on; Using form variables as globals can easily lead ; to possible security problems, if the code is not very well thought of. ; register_globals = On ; Determines whether the deprecated long $HTTP_*_VARS type predefined variables ; are registered by PHP or not. As they are deprecated, we obviously don't ; recommend you use them. They are on by default for compatibility reasons but ; they are not recommended on production servers. ; Default Value: On ; Development Value: Off ; Production Value: Off ; register_long_arrays = Off ; This directive determines whether PHP registers $argv & $argc each time it ; runs. $argv contains an array of all the arguments passed to PHP when a script ; is invoked. $argc contains an integer representing the number of arguments ; that were passed when the script was invoked. These arrays are extremely ; useful when running scripts from the command line. When this directive is ; enabled, registering these variables consumes CPU cycles and memory each time ; a script is executed. For performance reasons, this feature should be disabled ; on production servers. ; Note: This directive is hardcoded to On for the CLI SAPI ; Default Value: On ; Development Value: Off ; Production Value: Off ; register_argc_argv = Off ; When enabled, the SERVER and ENV variables are created when they're first ; used (Just In Time) instead of when the script starts. If these variables ; are not used within a script, having this directive on will result in a ; performance gain. The PHP directives register_globals, register_long_arrays, ; and register_argc_argv must be disabled for this directive to have any affect. ; auto_globals_jit = On

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  • Troubleshooting Website problems within the local network

    - by HaydnWVN
    Have an external website which opens fine on some PC's, yet seems to time out (or symptoms of timing out, but never actually does) on others. Seems to only affect (some) of our newer HP Pro 3305 MT Workstations. All of which are running Win7 32bit SP1 with all updates. Older PC's (Win7 32bit SP1 & WinXP) are unaffected. Using Google Chrome & Firefox makes no difference. Opening the website in IE9 Compatibility Mode has exactly the same symptoms. All PC's are on the same local network (Workgroup) using the same DNS server & gateway (inhouse) on the same internet connection, on the same subnet. There is no proxy server, no content filtering, no load balancing etc etc. Only group policy in effect (locally) is for Update scheduling. Local firewalls are all the same (Kaspersky WP4) and our external facing firewall has no IP specific settings. I have no control over the external website, traceroute shows the same destination on all PC's. It is a fairly popular website in our industry (Horticulture) and i'm not aware of any other people (even other sites within our sister companies) with the same problem. Update: Used Fiddler2 to monitor the HTTP request, seems its not getting fulfilled for some reason?! Request sent: GET http://www.rhs.org.uk/ HTTP/1.1 Host: www.rhs.org.uk Connection: keep-alive User-Agent: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/536.11 (KHTML, like Gecko) Chrome/20.0.1132.47 Safari/536.11 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Encoding: gzip,deflate,sdch Accept-Language: en-GB,en-US;q=0.8,en;q=0.6 Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3 Log from Fiddler 2 of the request: This session is not yet complete. Press F5 to refresh when session is complete for updated statistics. Request Count: 1 Bytes Sent: 567 (headers:567; body:0) Bytes Received: 0 (headers:0; body:0) ACTUAL PERFORMANCE -------------- ClientConnected: 17:02:33.720 ClientBeginRequest: 17:02:39.118 GotRequestHeaders: 17:02:39.118 ClientDoneRequest: 17:02:39.118 Determine Gateway: 0ms DNS Lookup: 0ms TCP/IP Connect: 46ms HTTPS Handshake: 0ms ServerConnected: 17:02:39.165 FiddlerBeginRequest: 17:02:39.165 ServerGotRequest: 17:02:39.165 ServerBeginResponse: 00:00:00.000 GotResponseHeaders: 00:00:00.000 ServerDoneResponse: 00:00:00.000 ClientBeginResponse: 00:00:00.000 ClientDoneResponse: 00:00:00.000 RESPONSE BYTES (by Content-Type) -------------- ~headers~: 0 Log of a successful request from a working PC (done this morning, excuse the timestamps being different from above): Request Count: 1 Bytes Sent: 493 (headers:493; body:0) Bytes Received: 20,413 (headers:525; body:19,888) ACTUAL PERFORMANCE -------------- ClientConnected: 08:22:47.766 ClientBeginRequest: 08:22:47.766 GotRequestHeaders: 08:22:47.766 ClientDoneRequest: 08:22:47.766 Determine Gateway: 0ms DNS Lookup: 26ms TCP/IP Connect: 30ms HTTPS Handshake: 0ms ServerConnected: 08:22:47.828 FiddlerBeginRequest: 08:22:47.828 ServerGotRequest: 08:22:47.828 ServerBeginResponse: 08:22:48.905 GotResponseHeaders: 08:22:48.905 ServerDoneResponse: 08:22:48.905 ClientBeginResponse: 08:22:48.905 ClientDoneResponse: 08:22:48.905 Overall Elapsed: 00:00:01.1388020 RESPONSE BYTES (by Content-Type) -------------- text/html: 19,888 ~headers~: 525 So my question has evolved into: What is the difference between the 2 requests and how do I determine why 1 PC is not getting a reply to it's GET request?

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  • Thoughts on home NAS server

    - by user826955
    I currently have a NAS with a 2x2TB HDD 1x16GB SSD layout on a mini-itx atom board. The NAS is in a Lian Li PC-Q07 case. On this system I was running freebsd 8 with a gmirror raid 1 setup, which was enough for my needs. So far I was using the NAS for: Fileserver with AFP protocol (only mac clients used) SVN server hosting all my source trees of my projects JIRA (performance was okay-ish) Timemachine backup for the macs The power consumption was about 38W, although I did not put HDDs asleep when unused (I think this is not possible in a raid setup). I liked the NAS because: the performance was good through gigabit LAN (enough for my needs) power consumption was good its a pretty small case and fits in one of my cupboards I disliked the NAS a bit because: it was a bit noisy, the Q07 case vibrated a good amount because of the HDDs. I switched the NAS off every evening I do not have a real backup of the data on the NAS, only the internal raid 1 as safety. I really dont want to loose my source trees under no circumstances, so I would really be sleeping better if I knew I had regular backups somewhere. Recently, the board seemed to have died, I can't boot anymore. Thus, I was thinking about a redesign of my NAS (I still have to find out what parts are broken, I probably need to replace the mainboard and SSD. HDDs seem to be okay). First of all, I was wondering what other users have as backup for their NAS? Are you actually using a second NAS, and regularly copying over the data to have it safe? Or is there any better solution to this? I was thinking about getting a cheap NAS like the synology DS112j with only one disk, and use rsync or something similar to regularly copy data over to the second NAS (wake the second NAS upon start, shut it down after copy). Although this approach seems somewhat weird, It would have the benefit (?) that I could use a single disk instead of raid in the main NAS, and put the disk asleep when idle, and have the NAS running 24/7 with low energy consumption (I found no way to do this with a gmirror setup). Is there any recommended backup solution for a small NAS? Then I was thinking about a different raid setup. Since I have to buy a new mainboard as well as SSD, I might as well switch over to a i3 board with more ram, and also switch to ZFS. I am not familar with ZFS, I've never used it, but I read and hear much about it. Would it be viable to set up a ZFS storage with only 2 disks? Can I easily extend this storage with more disks, once I choose to add some? I could maybe get a new case like the Fractal Design Array R2 which has more 3,5" slots. I could as well get another 2 disks, but I would prefer sticking with the existing 2 for enegery/heat/noise reasons. Should I go for a ZFS storage or stick to my gmirror setup? I would also like to keep freebsd as operating system, and also I dont need any web gui or something (that is, I dont need/want to use FreeNAS or Openfiler etc). Does anyone maybe have a sample setup in use so I can compare energy consumption/noise/software setup? Any guidance towards the NAS of my dreams (silent, low energy, safe w/ backups) much appreciated.

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  • CPU Utilization LAMP stack

    - by Max
    We've got an ec2 m2.4xlarge running Magento (centos 5.6, httpd 2.2, php 5.2.17 with eaccelerator 0.9.5.3, mysql 5.1.52). Right now we're getting a large traffic spike, and our top looks like this: top - 09:41:29 up 31 days, 1:12, 1 user, load average: 120.01, 129.03, 113.23 Tasks: 1190 total, 18 running, 1172 sleeping, 0 stopped, 0 zombie Cpu(s): 97.3%us, 1.8%sy, 0.0%ni, 0.5%id, 0.0%wa, 0.0%hi, 0.0%si, 0.4%st Mem: 71687720k total, 36898928k used, 34788792k free, 49692k buffers Swap: 880737784k total, 0k used, 880737784k free, 1586524k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2433 mysql 15 0 23.6g 4.5g 7112 S 564.7 6.6 33607:34 mysqld 24046 apache 16 0 411m 65m 28m S 26.4 0.1 0:09.05 httpd 24360 apache 15 0 410m 60m 25m S 26.4 0.1 0:03.65 httpd 24993 apache 16 0 410m 57m 21m S 26.1 0.1 0:01.41 httpd 24838 apache 16 0 428m 74m 20m S 24.8 0.1 0:02.37 httpd 24359 apache 16 0 411m 62m 26m R 22.3 0.1 0:08.12 httpd 23850 apache 15 0 411m 64m 27m S 16.8 0.1 0:14.54 httpd 25229 apache 16 0 404m 46m 17m R 10.2 0.1 0:00.71 httpd 14594 apache 15 0 404m 63m 34m S 8.4 0.1 1:10.26 httpd 24955 apache 16 0 404m 50m 21m R 8.4 0.1 0:01.66 httpd 24313 apache 16 0 399m 46m 22m R 8.1 0.1 0:02.30 httpd 25119 apache 16 0 411m 59m 23m S 6.8 0.1 0:01.45 httpd Questions: Would giving msyqld more memory help it cache queries and react faster? If so, how? Other than splitting mysql and php to separate servers (which we're about to do) is there anything else we could/should be doing? Thanks! UPDATE: Here's our my.cnf along with the output of mysqltuner. It looks like a cache problem. Thanks again! # cat /etc/my.cnf [client] port = **** socket = /var/lib/mysql/mysql.sock [mysqld] datadir=/mnt/persistent/mysql port=**** socket=/var/lib/mysql/mysql.sock key_buffer = 512M max_allowed_packet = 64M table_cache = 1024 sort_buffer_size = 8M read_buffer_size = 4M read_rnd_buffer_size = 2M myisam_sort_buffer_size = 64M thread_cache_size = 128M tmp_table_size = 128M join_buffer_size = 1M query_cache_limit = 2M query_cache_size= 64M query_cache_type = 1 max_connections = 1000 thread_stack = 128K thread_concurrency = 48 log-bin=mysql-bin server-id = 1 wait_timeout = 300 innodb_data_home_dir = /mnt/persistent/mysql/ innodb_data_file_path = ibdata1:10M:autoextend innodb_buffer_pool_size = 20G innodb_additional_mem_pool_size = 20M innodb_log_file_size = 64M innodb_log_buffer_size = 8M innodb_flush_log_at_trx_commit = 1 innodb_lock_wait_timeout = 50 innodb_thread_concurrency = 48 ft_min_word_len=3 [myisamchk] ft_min_word_len=3 key_buffer = 128M sort_buffer_size = 128M read_buffer = 2M write_buffer = 2M # ./mysqltuner.pl >> MySQLTuner 1.2.0 - Major Hayden <[email protected]> >> Bug reports, feature requests, and downloads at http://mysqltuner.com/ >> Run with '--help' for additional options and output filtering -------- General Statistics -------------------------------------------------- [--] Skipped version check for MySQLTuner script [OK] Currently running supported MySQL version 5.1.52-log [OK] Operating on 64-bit architecture -------- Storage Engine Statistics ------------------------------------------- [--] Status: +Archive -BDB +Federated +InnoDB -ISAM -NDBCluster [--] Data in MyISAM tables: 2G (Tables: 26) [--] Data in InnoDB tables: 749M (Tables: 250) [!!] Total fragmented tables: 262 -------- Security Recommendations ------------------------------------------- -------- Performance Metrics ------------------------------------------------- [--] Up for: 31d 2h 30m 38s (680M q [253.371 qps], 2M conn, TX: 4825B, RX: 236B) [--] Reads / Writes: 89% / 11% [--] Total buffers: 20.6G global + 15.1M per thread (1000 max threads) [OK] Maximum possible memory usage: 35.4G (51% of installed RAM) [OK] Slow queries: 0% (35K/680M) [OK] Highest usage of available connections: 53% (537/1000) [OK] Key buffer size / total MyISAM indexes: 512.0M/457.2M [OK] Key buffer hit rate: 100.0% (9B cached / 264K reads) [OK] Query cache efficiency: 42.3% (260M cached / 615M selects) [!!] Query cache prunes per day: 4384652 [OK] Sorts requiring temporary tables: 0% (1K temp sorts / 38M sorts) [!!] Joins performed without indexes: 100404 [OK] Temporary tables created on disk: 17% (7M on disk / 45M total) [OK] Thread cache hit rate: 99% (537 created / 2M connections) [!!] Table cache hit rate: 0% (1K open / 946K opened) [OK] Open file limit used: 9% (453/5K) [OK] Table locks acquired immediately: 99% (758M immediate / 758M locks) [OK] InnoDB data size / buffer pool: 749.3M/20.0G -------- Recommendations ----------------------------------------------------- General recommendations: Run OPTIMIZE TABLE to defragment tables for better performance Enable the slow query log to troubleshoot bad queries Adjust your join queries to always utilize indexes Increase table_cache gradually to avoid file descriptor limits Variables to adjust: query_cache_size (> 64M) join_buffer_size (> 1.0M, or always use indexes with joins) table_cache (> 1024)

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  • Apache config that uses two document roots based on whether the requested resource exists in the first

    - by mattalexx
    Background I have a client site that consists of a CakePHP installation and a Magento installation: /web/example.com/ /web/example.com/app/ <== CakePHP /web/example.com/app/webroot/ <== DocumentRoot /web/example.com/app/webroot/store/ <== Magento /web/example.com/config/ <== Site-wide config /web/example.com/vendors/ <== Site-wide libraries The server runs Apache 2.2.3. The problem The whole company has FTP access and got used to clogging up the /web/example.com/, /web/example.com/app/webroot/, and /web/example.com/app/webroot/store/ directories with their own files. Sometimes these files need HTTP access and sometimes they don't. In any case, this mess makes my job harder when it comes to maintaining the site. Code merges, tarring the live code, etc, is very complicated and usually requires a bunch of filters. Abandoned solution At first, I thought I would set up a new subdomain on the same server, move all of their files there, and change their FTP chroot. But that wouldn't work for these reasons: Firstly, I have no idea (and neither do they remember) what marketing materials they've sent out that contain URLs to certain resources they've uploaded to the server, using the main domain, and also using abstract subdomains that use the main virtual host because it has ServerAlias *.example.com. So suddenly having them only use static.example.com isn't feasible. Secondly, The PHP scripts in their projects are potentially very non-portable. I want their files to stay in as similar an environment as they were built as I can. Also, I do not want to debug their code to make it portable. Half-baked solution After some thought, I decided to find a way to section off the actual website files into another directory that they would not touch. The company's uploaded files would stay where they were. This would ensure that I didn't break any of their projects that needed HTTP access. It would look something like this: /web/example.com/ <== A bunch of their files are in here /web/example.com/app/webroot/ <== 1st DocumentRoot; A bunch of their files are in here /web/example.com/app/webroot/store/ <== Some more are in here /web/example.com/site/ <== New dir; Contains only site files /web/example.com/site/app/ <== CakePHP /web/example.com/site/app/webroot/ <== 2nd DocumentRoot /web/example.com/site/app/webroot/store/ <== Magento /web/example.com/site/config/ <== Site-wide config /web/example.com/site/vendors/ <== Site-wide libraries After I made this change, I would not need to pay attention to anything except for the stuff within /web/example.com/site/ and my job would be a lot easier. I would be the only one changing stuff in there. So here's where the Apache magic would happen: I need an HTTP request to http://www.example.com/ to first use /web/example.com/app/webroot/ as the document root. If nothing is found (no miscellaneous uploaded company projects are found), try finding something within /web/example.com/site/app/webroot/. Another thing to keep in mind is, the site might have some problems if the $_SERVER['DOCUMENT_ROOT'] variable reads /web/example.com/app/webroot/ but the actual files are within /web/example.com/site/app/webroot/. It would be better if the DOCUMENT_ROOT environment variable could be /web/example.com/site/app/webroot/ for anything within the /web/example.com/site/app/webroot/ directory. Conclusion Is my half-baked solution possible with Apache 2.2.3? Is there a better way to solve this problem?

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  • Using different SSDs types (not only SATA based) as system drive

    - by Hubert Kario
    Currently I have a Thinkpad X61s and want to make it both a bit faster and a bit more power efficient. For that reason I thought that adding SSD drive would make most sense. Unfortunately, because of financial reasons, buying SSD of over 200GB capacity is out of reach for me (not only it would be worth more than the rest of the laptop, but also I currently have a 500GB drive in it, so even such a drive would be kind of a downgrade for me). During preliminary testing with a cheap Transcend 4GB Class 6 (14MiB/s streaming, 9MiB/s random read) card I experienced boot times to be reduced by half so putting the OS only on it would already would be an improvement. Unfortunately, my system now is about 11GiB in size so anything less than 16GB would be constraining. In this laptop I can connect additional drives on at least 5 different ways: using SATA-ATA converter caddy in the X6 Ultrabase using internal mini PCIe slot using integrated SDHC slot using CardBus (a.k.a PCMCIA or PC Card) slot using USB Thankfully, because I use only Linux on this PC the bootability of them is irrelevant as I can put the /boot partition on internal HDD and / on any of the above mentioned Flash memories (as I already did for the SDHC test). From what I was able to research and from my own experience those options come with rather big downsides or other problems: SATA-ATA caddy It has three downsides: I have to carry the Ultrabse with me at all times (it's not really inconvenient, but those grams do add) and couldn't disconnect it when I want to disconnect the battery It makes the bay unusable for the optical drive and occasional quick access to other hard drives the only caddies I could buy have rather flaky controllers in them so putting my OS on it would hamper its stability Internal mini PCIe slot This would be an ideal solution, if only I could find real PCIe SSDs, not only devices that could talk only SATA or ATA over PCIe mechanical connection (the ones used in Dell Mini or Asus EEE). Theoretically Samsung did release such devices but I couldn't find them in retail anywhere. Integrated SDHC slot It's a nice solution with a single drawback: the fastest 16GB SDHC card on the market can only do around 35MiB/s read and 15MiB/s write while still costing like a normal 40GB SATA SSD that's 10 times faster. Not really cost-effective. CardBus (a.k.a PCMCIA or PC Card) slot Those cards are much faster than the SDHC option (there are ones that can do well over 50MiB/s read in benchmarks) and from what I could find the PCMCIA controller in my laptop does support UDMA so it should be able to deliver comparable speeds. They still cost similarly to SD cards but at least they provide streaming performance comparable to my current HDD. USB That's the worst option. Not only is it limited to 20-30MiB/s by the interface itself the drive would stick out of the laptop so it's a big no no. The question As such I think that going the "CF in a CardBus adapter" route will be the best option. My question is: did anyone try using CF cards in CardBus adapters as system drives with Linux on Thinkpad laptops? Laptops in general? What was the real-world performance? I don't have any CF cards so I can't check how well does it work with suspend/resume, or whatever it's easy to make it work in initramfs (I'm using ArchLinux and SD card was trivial — add 3 modules in single config line and rebuilding initramfs) so any tips/gotchas on this are welcome as well.

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  • Rosewill RSV-S5 and it's transferespeeds

    - by DoomStone
    I have just bought a Rosewill RSV-S5, I have installed 5x1,5Tb Western Digital Green disks in it. After that have I created a Raid5 on them all with the software that followed with the hardware. Not the raid it self works fine, but it is SLOW, I can only obtain a maximum of 25 MB/s, and if SABnzbd+ is downloading with 5 MB/s is it having a hard time streaming a normal DIVX (700 mb) movie. Is this normal or is there something wrong? Edit: should be able to handle 3 Gbps = 384 megabytes / second Edit 2: As you can see am I only downloading with 3,76 MB/s and I'm trying to watch V s02e08 (720p), but it is completely unwatchable, as I can see 30 sec, and the it buffers for 20 sec. Edit: Other information there might be required I'm running Windows Server 2008 R2, optimized for program performance. Windows is installed on a 60GB SSD. I have a 50 Mb/s internet connection and a 1 Gb/s LAN, all connected with Cat6 Ethernet cables. The MCE is using a Gigabyte EP35C-DS3R motherboard with 2 GB DDR2 ram. Edit 3: I have used chunk sizes for 128 KB Edit 4: I found this on newegg Pros: Enclosure for 5x2TB hard drive is fine. This is basically a rebranded San Digital TR5M-B product. For support Rosewill tells you to contact San Digital. No direct support from Silicon Image for the computer raid card. Cons: Includes computer Silicon Image 3132 raid card, extremely slow raid 5 write (our tests ~10MB/s). Compare to regular internal local drive write 30-60MB/s. We basically dumped the Sil3132 card and replaced with High Point RocketRaid 622 card for extra $69.99. Note for RR622, turn off ECRC (end to end CRC check) for card to work on IBM xserver. What took 12hrs to copy now took 2-3hrs. San Digital realized the problem and has the newer model TR5M-BP TowerRaid Plus that comes with High Point RocketRaid 622 card. Rosewill should discontinue this product and go with TR5M-BP. Could not get Silicon Image raid management software to work with complicated 2008R2 server with 10 NICs, application doesn't know how to talk to localhost port with all those NICs. No updates from Silicon Image and support from San Digital ignored. Gave up on Sil3132 card. Save yourself from a lot of headaches, get the RR622 card too if you are going to buy this product. Other Thoughts: The newer model is TR5M-BP TowerRaid Plus, comes with High Point RocketRaid 622 raid card for the PC instead of Silicon Image Sil3132. According to San Digital, raid 5 performance for Sil3132 read 80MB/s write 19MB/s, and RR622 read 154MB/s write 149MB/s. Our RR622 tests gave (8TB raid 5) write ~80-110MB/s copying 40GB file took 8mins. So I have now ordered a HighPoint RocketRAID 622 2P ext SATA III and hopes that it will solve my problems.

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  • Network config / gear question

    - by mcgee1234
    I have been tasked with setting up a fairly straightforward rack in a data center (we do not even need a whole rack, but this is the smallest allotment available). In a nutshell, 4 to 6 servers need to be able to reach 2 (maybe 3) vendors. The servers needs to be reachable over the internet. A little more detail - the networks the servers need to reach are inside of the data center, and are "trusted". Connections to these networks will be achieved through intra data center cross connects. It is kind of like a manufacturing line where we receive data from one vendor (burst-able up to 200 Mbits), churn through it on the servers, and then send out data to another vendor (bursts up to 20 Mbits). This series of events is very latency sensitive, so much so that it is common practice not to use NAT or a firewall on these segments (or so I hear). To reach the servers over the internet, I plan to use a site to site VPN. (This part is only relevant as far as hardware selection goes). I have 2 configurations in mind: Cisco 2911 (2921) (with the additional wan ports module) and a layer 2 switch - in this scenario, I would use the router also for VPN. Cisco 3560 layer 3 switch to interconnect the networks inside of the data center and an ASA 5510 (which is total overkill, but the 5505 is not rack mountable) as a firewall for the Wan side (internet) and VPN. I envision the setup to be as follows: Internet - ASA - 3560 Vendors - 3560 - Servers The general idea is that the ASA acts as a firewall and VPN device and the 3560 does all the heavy lifting. The first is a fairly traditional setup but my concern is performance. The second is somewhat unorthodox in that the vendors are directly connected to the layer 3 switch without passing through a firewall. Based on my understanding however, a layer 3 switch will perform substantially better as it will do hardware (ASIC) vs. software switching. (Note that number 2 is a little over the budget, but not unworkable (double negative, ugh)) Since this is my first time dealing with a data center, I am not sure what the IP space is going to look like. I suspect I will retain a block(s) of public IPs, vlan them to individual interfaces for the vendor connections and the servers (which will not reachable from the wan side of course) and setup routing on the switch. So here are my questionss: Is there a substantial performance difference between 1 and 2, i.e. hardware based switching on a layer 3 vs a software base on the 2911? I have trolled the internet and found a lot of Cisco literature, but nothing that I could really use to get a good handle. The vendors we connect to are secure and trusted (famous last words) and as I understand it, it is common practice not to NAT or firewall these connections (because of the aforementioned latency sensitivity). But what what kind of latency are we really talking about if I push the data through a router (or even ASA for that matter)? For our purposes, 5 ms will not kill us, 20 or 30 can be very costly. Others measure in microseconds, but they are out of our league. Is there any issues with using public IPs on a layer 3 switch? I am certainly not married to either of these configs, and I am totally open to any ideas. My knowledge (and I use the term loosely) is largely from books so I welcome any advice / insight. Thanks in advance.

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  • ActiveX component can't create Object Error? Check 64 bit Status

    - by Rick Strahl
    If you're running on IIS 7 and a 64 bit operating system you might run into the following error using ASP classic or ASP.NET with COM interop. In classic ASP applications the error will show up as: ActiveX component can't create object   (Error 429) (actually without error handling the error just shows up as 500 error page) In my case the code that's been giving me problems has been a FoxPro COM object I'd been using to serve banner ads to some of my pages. The code basically looks up banners from a database table and displays them at random. The ASP classic code that uses it looks like this: <% Set banner = Server.CreateObject("wwBanner.aspBanner") banner.BannerFile = "wwsitebanners" Response.Write(banner.GetBanner(-1)) %> Originally this code had no specific error checking as above so the ASP pages just failed with 500 error pages from the Web server. To find out what the problem is this code is more useful at least for debugging: <% ON ERROR RESUME NEXT Set banner = Server.CreateObject("wwBanner.aspBanner") Response.Write(err.Number & " - " & err.Description) banner.BannerFile = "wwsitebanners" Response.Write(banner.GetBanner(-1)) %> which results in: 429 - ActiveX component can't create object which at least gives you a slight clue. In ASP.NET invoking the same COM object with code like this: <% dynamic banner = wwUtils.CreateComInstance("wwBanner.aspBanner") as dynamic; banner.cBANNERFILE = "wwsitebanners"; Response.Write(banner.getBanner(-1)); %> results in: Retrieving the COM class factory for component with CLSID {B5DCBB81-D5F5-11D2-B85E-00600889F23B} failed due to the following error: 80040154 Class not registered (Exception from HRESULT: 0x80040154 (REGDB_E_CLASSNOTREG)). The class is in fact registered though and the COM server loads fine from a command prompt or other COM client. This error can be caused by a COM server that doesn't load. It looks like a COM registration error. There are a number of traditional reasons why this error can crop up of course. The server isn't registered (run regserver32 to register a DLL server or /regserver on an EXE server) Access permissions aren't set on the COM server (Web account has to be able to read the DLL ie. Network service) The COM server fails to load during initialization ie. failing during startup One thing I always do to check for COM errors fire up the server in a COM client outside of IIS and ensure that it works there first - it's almost always easier to debug a server outside of the Web environment. In my case I tried the server in Visual FoxPro on the server with: loBanners = CREATEOBJECT("wwBanner.aspBanner") loBanners.cBannerFile = "wwsitebanners" ? loBanners.GetBanner(-1) and it worked just fine. If you don't have a full dev environment on the server you can also use VBScript do the same thing and run the .vbs file from the command prompt: Set banner = Server.CreateObject("wwBanner.aspBanner") banner.BannerFile = "wwsitebanners" MsgBox(banner.getBanner(-1)) Since this both works it tells me the server is registered and working properly. This leaves startup failures or permissions as the problem. I double checked permissions for the Application Pool and the permissions of the folder where the DLL lives and both are properly set to allow access by the Application Pool impersonated user. Just to be sure I assigned an Admin user to the Application Pool but still no go. So now what? 64 bit Servers Ahoy A couple of weeks back I had set up a few of my Application pools to 64 bit mode. My server is Server 2008 64 bit and by default Application Pools run 64 bit. Originally when I installed the server I set up most of my Application Pools to 32 bit mainly for backwards compatibility. But as more of my code migrates to 64 bit OS's I figured it'd be a good idea to see how well code runs under 64 bit code. The transition has been mostly painless. Until today when I noticed the problem with the code above when scrolling to my IIS logs and noticing a lot of 500 errors on many of my ASP classic pages. The code in question in most of these pages deals with this single simple COM object. It took a while to figure out that the problem is caused by the Application Pool running in 64 bit mode. The issue is that 32 bit COM objects (ie. my old Visual FoxPro COM component) cannot be loaded in a 64 bit Application Pool. The ASP pages using this COM component broke on the day I switched my main Application Pool into 64 bit mode but I didn't find the problem until I searched my logs for errors by pure chance. To fix this is easy enough once you know what the problem is by switching the Application Pool to Enable 32-bit Applications: Once this is done the COM objects started working correctly again. 64 bit ASP and ASP.NET with DCOM Servers This is kind of off topic, but incidentally it's possible to load 32 bit DCOM (out of process) servers from ASP.NET and ASP classic even if those applications run in 64 bit application pools. In fact, in West Wind Web Connection I use this capability to run a 64 bit ASP.NET handler that talks to a 32 bit FoxPro COM server which allows West Wind Web Connection to run in native 64 bit mode without custom configuration (which is actually quite useful). It's probably not a common usage scenario but it's good to know that you can actually access 32 bit COM objects this way from ASP.NET. For West Wind Web Connection this works out well as the DCOM interface only makes one non-chatty call to the backend server that handles all the rest of the request processing. Application Pool Isolation is your Friend For me the recent incident of failure in the classic ASP pages has just been another reminder to be very careful with moving applications to 64 bit operation. There are many little traps when switching to 64 bit that are very difficult to track and test for. I described one issue I had a couple of months ago where one of the default ASP.NET filters was loading the wrong version (32bit instead of 64bit) which was extremely difficult to track down and was caused by a very sneaky configuration switch error (basically 3 different entries for the same ISAPI filter all with different bitness settings). It took me almost a full day to track this down). Recently I've been taken to isolate individual applications into separate Application Pools rather than my past practice of combining many apps into shared AppPools. This is a good practice assuming you have enough memory to make this work. Application Pool isolate provides more modularity and allows me to selectively move applications to 64 bit. The error above came about precisely because I moved one of my most populous app pools to 64 bit and forgot about the minimal COM object use in some of my old pages. It's easy to forget. To 64bit or Not Is it worth it to move to 64 bit? Currently I'd say -not really. In my - admittedly limited - testing I don't see any significant performance increases. In fact 64 bit apps just seem to consume considerably more memory (30-50% more in my pools on average) and performance is minimally improved (less than 5% at the very best) in the load testing I've performed on a couple of sites in both modes. The only real incentive for 64 bit would be applications that require huge data spaces that exceed the 32 bit 4 gigabyte memory limit. However I have a hard time imagining an application that needs 4 gigs of memory in a single Application Pool :-). Curious to hear other opinions on benefits of 64 bit operation. © Rick Strahl, West Wind Technologies, 2005-2011Posted in COM   ASP.NET  FoxPro  

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  • Week in Geek: FBI Back Door in OpenBSD Edition

    - by Asian Angel
    This week we learned how to migrate bookmarks from Delicious to Diigo, fix annoying arrows, play old-school DOS games, schedule smart computer shutdowns, use breaks in Microsoft Word to better format documents, check the condition of hard-disks using Linux disk utilities, & what the Linux fstab is and how it works. Photo by Jameson42. Random Geek Links Another week with extra news link goodness to help keep you up to date. Photo by justmakeit. Report of FBI back door roils OpenBSD community Allegations that the FBI surreptitiously placed a back door into the OpenBSD operating system have alarmed the computer security community, prompting calls for an audit of the source code and claims that the charges must be a hoax. Fortinet: Job outlook improving for cybercrooks In an ironic twist in the job market, more positions will open up for developers who can write customized malware packers, people who can break CAPTCHA codes, and distributors who can spread malicious code, according to Fortinet. Enisa: Malware for smartphones is a ’serious risk’ Businesses and consumers are at risk of data breaches through smartphone use, according to the European Network and Information Security Agency. The trick with the f: Google and Microsoft web sites distribute malware Last week, Google’s DoubleClick advertising platform and Microsoft’s rad.msn.com online ad network briefly distributed malware to other web sites in the form of advertising banners. New scam tactic: Fake disk defraggers It would appear that scammers are trying out new programs to see which might best confuse potential victims and evade detection by legitimate antivirus software. Microsoft closes IE and Stuxnet holes As previously announced, Microsoft has released 17 security updates to close 40 security holes. All four Windows holes so far disclosed in connection with Stuxnet have now been closed. Microsoft Offers H.264 Support to Firefox on Windows via Add-On The new HTML5 Extension for Windows Media Player Firefox Plug-in add-on from Microsoft offers users that are running Firefox on Windows 7 H.264 support for HTML5 video playback. Google proclaims Chrome business-ready Google has announced that Chrome is ready for corporate use. Microsoft Tells Exchange Customers to Think Twice Before Opting for Google Message Continuity This week, Microsoft is telling companies still running Exchange 2010’s precursors that they should carefully consider the implications of embracing Google Message Continuity. Who Google has in mind for its Chrome OS users Steven Vaughan-Nichols explains why he feels that Chrome OS will be ideal for either office-workers or people who need a computer, but do not know the first thing about how to use one safely. Oracle takes office suite to the cloud Oracle has introduced Cloud Office 1.0, a cloud-based version of its office suite, which is aimed at web and mobile users. Mozilla pays premiums for reports of vulnerabilities The Mozilla Foundation has followed Google’s example by expanding its rewards program for reports of vulnerabilities in its Web applications. Who bought those 882 Novell patents? Not just Microsoft The mysterious CPTN Holdings — the organization that bought the 882 Novell patents as part of the terms of the Attachmate acquisition of Novell – has been unmasked (Microsoft, Apple, EMC and Oracle). Appeals court: Feds need warrants for e-mail Police must obtain search warrants before perusing Internet users’ e-mail records, a federal appeals court ruled today in a landmark decision that struck down part of a 1986 law allowing warrantless access. Geek Video of the Week What happens when someone plays a wicked prank by shoveling crazy snow paths that lead to dead ends or turn back on themselves? Watch to find out! Photo by CollegeHumor. Janitor Snow Shoveling Prank Random TinyHacker Links The Oatmeal on Cat vs Internet What lengths will our poor neglected kitty hero have to go to in order to get some attention? Guide On Using JoliCloud With Windows JoliCloud is a nifty operating system that’s made for people who need a light-weight OS that’s mostly cloud based. Check this guide on using it with Windows. Use Cameyo to Easily Create Portable Programs Here’s a nifty tool to make portable apps out of programs in Windows. Check out the guide to do it. Better Family Tech Support A nice new site by Google to help members of family understand how computers work. Track Your Stolen Mobile Phone With F-Secure A useful anti-theft tool for your mobile phone. Super User Questions Another week with great answers to popular questions from Super User. What Chrome password manager fits my requirements? What’s the best way to be able to reimage windows computers? Could you suggest feature-rich disk-based personal backup program for linux (and I’ve seen a few)? What is IPv6 and why should I care? Is there any way to find out what programs are trying to connect to Internet on windows? How-To Geek Weekly Article Recap Here are our hottest articles full of geeky goodness from this past week at HTG. 20 OS X Keyboard Shortcuts You Might Not Know Microsoft Security Essentials 2.0 Kills Viruses Dead. Download It Now. Is Your Desktop Printer More Expensive Than Printing Services? Ask the Readers: Would You Be Willing to Give Windows Up and Use a Different O.S.? The Twelve Days of Geekmas One Year Ago on How-To Geek Enjoy reading through our latest batch of retro-geek goodness from one year ago. Macrium Reflect is a Free and Easy To Use Backup Utility How To Turn a Physical Computer Into A Virtual Machine with Disk2vhd How To Restore Windows 7 from a System Image How To Manage Hard Drive Space Used by Windows 7 Backup and Restore How To Manage Hibernate Mode in Windows 7 The Geek Note That is all we have for you this week, so see you back here again after the holidays! Got a great tip? Send it in to us at [email protected]. Photo by mitjamavsar. Latest Features How-To Geek ETC The Complete List of iPad Tips, Tricks, and Tutorials The 50 Best Registry Hacks that Make Windows Better The How-To Geek Holiday Gift Guide (Geeky Stuff We Like) LCD? LED? Plasma? The How-To Geek Guide to HDTV Technology The How-To Geek Guide to Learning Photoshop, Part 8: Filters Improve Digital Photography by Calibrating Your Monitor Deathwing the Destroyer – WoW Cataclysm Dragon Wallpaper Drag2Up Lets You Drag and Drop Files to the Web With Ease The Spam Police Parts 1 and 2 – Goodbye Spammers [Videos] Snow Angels Theme for Windows 7 Exploring the Jungle Ruins Wallpaper Protect Your Privacy When Browsing with Chrome and Iron Browser

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  • Creating a dynamic proxy generator with c# – Part 2 – Interceptor Design

    - by SeanMcAlinden
    Creating a dynamic proxy generator – Part 1 – Creating the Assembly builder, Module builder and caching mechanism For the latest code go to http://rapidioc.codeplex.com/ Before getting too involved in generating the proxy, I thought it would be worth while going through the intended design, this is important as the next step is to start creating the constructors for the proxy. Each proxy derives from a specified type The proxy has a corresponding constructor for each of the base type constructors The proxy has overrides for all methods and properties marked as Virtual on the base type For each overridden method, there is also a private method whose sole job is to call the base method. For each overridden method, a delegate is created whose sole job is to call the private method that calls the base method. The following class diagram shows the main classes and interfaces involved in the interception process. I’ll go through each of them to explain their place in the overall proxy.   IProxy Interface The proxy implements the IProxy interface for the sole purpose of adding custom interceptors. This allows the created proxy interface to be cast as an IProxy and then simply add Interceptors by calling it’s AddInterceptor method. This is done internally within the proxy building process so the consumer of the API doesn’t need knowledge of this. IInterceptor Interface The IInterceptor interface has one method: Handle. The handle method accepts a IMethodInvocation parameter which contains methods and data for handling method interception. Multiple classes that implement this interface can be added to the proxy. Each method override in the proxy calls the handle method rather than simply calling the base method. How the proxy fully works will be explained in the next section MethodInvocation. IMethodInvocation Interface & MethodInvocation class The MethodInvocation will contain one main method and multiple helper properties. Continue Method The method Continue() has two functions hidden away from the consumer. When Continue is called, if there are multiple Interceptors, the next Interceptors Handle method is called. If all Interceptors Handle methods have been called, the Continue method then calls the base class method. Properties The MethodInvocation will contain multiple helper properties including at least the following: Method Name (Read Only) Method Arguments (Read and Write) Method Argument Types (Read Only) Method Result (Read and Write) – this property remains null if the method return type is void Target Object (Read Only) Return Type (Read Only) DefaultInterceptor class The DefaultInterceptor class is a simple class that implements the IInterceptor interface. Here is the code: DefaultInterceptor namespace Rapid.DynamicProxy.Interception {     /// <summary>     /// Default interceptor for the proxy.     /// </summary>     /// <typeparam name="TBase">The base type.</typeparam>     public class DefaultInterceptor<TBase> : IInterceptor<TBase> where TBase : class     {         /// <summary>         /// Handles the specified method invocation.         /// </summary>         /// <param name="methodInvocation">The method invocation.</param>         public void Handle(IMethodInvocation<TBase> methodInvocation)         {             methodInvocation.Continue();         }     } } This is automatically created in the proxy and is the first interceptor that each method override calls. It’s sole function is to ensure that if no interceptors have been added, the base method is still called. Custom Interceptor Example A consumer of the Rapid.DynamicProxy API could create an interceptor for logging when the FirstName property of the User class is set. Just for illustration, I have also wrapped a transaction around the methodInvocation.Coninue() method. This means that any overriden methods within the user class will run within a transaction scope. MyInterceptor public class MyInterceptor : IInterceptor<User<int, IRepository>> {     public void Handle(IMethodInvocation<User<int, IRepository>> methodInvocation)     {         if (methodInvocation.Name == "set_FirstName")         {             Logger.Log("First name seting to: " + methodInvocation.Arguments[0]);         }         using (TransactionScope scope = new TransactionScope())         {             methodInvocation.Continue();         }         if (methodInvocation.Name == "set_FirstName")         {             Logger.Log("First name has been set to: " + methodInvocation.Arguments[0]);         }     } } Overridden Method Example To show a taster of what the overridden methods on the proxy would look like, the setter method for the property FirstName used in the above example would look something similar to the following (this is not real code but will look similar): set_FirstName public override void set_FirstName(string value) {     set_FirstNameBaseMethodDelegate callBase =         new set_FirstNameBaseMethodDelegate(this.set_FirstNameProxyGetBaseMethod);     object[] arguments = new object[] { value };     IMethodInvocation<User<IRepository>> methodInvocation =         new MethodInvocation<User<IRepository>>(this, callBase, "set_FirstName", arguments, interceptors);          this.Interceptors[0].Handle(methodInvocation); } As you can see, a delegate instance is created which calls to a private method on the class, the private method calls the base method and would look like the following: calls base setter private void set_FirstNameProxyGetBaseMethod(string value) {     base.set_FirstName(value); } The delegate is invoked when methodInvocation.Continue() is called within an interceptor. The set_FirstName parameters are loaded into an object array. The current instance, delegate, method name and method arguments are passed into the methodInvocation constructor (there will be more data not illustrated here passed in when created including method info, return types, argument types etc.) The DefaultInterceptor’s Handle method is called with the methodInvocation instance as it’s parameter. Obviously methods can have return values, ref and out parameters etc. in these cases the generated method override body will be slightly different from above. I’ll go into more detail on these aspects as we build them. Conclusion I hope this has been useful, I can’t guarantee that the proxy will look exactly like the above, but at the moment, this is pretty much what I intend to do. Always worth downloading the code at http://rapidioc.codeplex.com/ to see the latest. There will also be some tests that you can debug through to help see what’s going on. Cheers, Sean.

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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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