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Apache Performance Tuning

Apache Performance Tuning. Part 1: Scaling Up. Sander Temme <sander@temme.net>. Who am I?. Member, Apache Software Foundation Lurker on dev@httpd Infrastructure Team Member Contractor Walt Disney Imagineering ADP University of California Currently unemployed….

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Apache Performance Tuning

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  1. Apache Performance Tuning Part 1: Scaling Up Sander Temme <sander@temme.net>

  2. Who am I? • Member, Apache Software Foundation • Lurker on dev@httpd • Infrastructure Team Member • Contractor • Walt Disney Imagineering • ADP • University of California • Currently unemployed…

  3. http://httpd.apache.org/docs/1.3/misc/perf-tuning.html says: “Apache is a general webserver, which is designed to be correct first, and fast second. Even so, its performance is quite satisfactory. Most sites have less than 10Mbits of outgoing bandwidth, which Apache can fill using only a low end Pentium-based webserver.”

  4. Goals of Performance Tuning • Serve as Many Requests as Possible • Graceful Degradation • (Don’t crash the box)

  5. Assumptions • Limited Resources • Work With What You Have • You’re probably running Linux • No Compiling or Recompiling! • You can find httpd.conf

  6. Monitoring Your Server

  7. Purposes of Monitoring • Observation • Extrapolation • Signals/Alerts • Testing

  8. Monitoring Apache

  9. Monitoring Solaris: SE Toolkit • Lightweight • Programmable • Alive http://www.sunfreeware.com/setoolkit.html

  10. Other Monitoring Tools • vmstat • iostat • top • free

  11. Web Server Logs • ErrorLog • LogLevel: debug, info, notice, warn, error, crit • Access Log: TransferLog or CustomLog • Common Log Format

  12. Common Log Format 172.16.2.91 - - [16/Nov/2003:15:23:27 -0800] "GET /~sctemme/ HTTP/1.1" 200 1446 172.16.2.91 - - [16/Nov/2003:15:23:28 -0800] "GET /~sctemme/css/doc.css HTTP/1.1" 200 167 172.16.2.91 - - [16/Nov/2003:15:23:28 -0800] "GET /~sctemme/css/menu.css HTTP/1.1" 200 623 172.16.2.91 - - [16/Nov/2003:15:23:29 -0800] "GET /favicon.ico HTTP/1.1" 404 283 172.16.2.91 - - [16/Nov/2003:15:23:34 -0800] "GET /~sctemme/index.html HTTP/1.1" 200 1446

  13. Log File Analysis • Analog • Fast • Cryptic output • Webalizer • Not as fast • Nicer output • Patched version available w/ GeoIP, DNS, 404 support (Google for it) http://www.mrunix.net/webalizer/http://www.analog.cx/

  14. Webalizer Output

  15. Webalizer Output Detail

  16. Configuring for Performance • Configuring Apache • Tuning the Operating System

  17. Apache Configuration • Process/Thread Management • DNS Lookups • Avoid .htaccess Files • Disable unused modules • Tune your App Tier

  18. Selecting Your MPM • Apache 2.x only! • Processes and Threads • Differences between platforms • Thread-safety issues

  19. Processes and Threads • Process: • Own copy of data structures • Shares: program code, shared memory • Context switches expensive • Thread: • Runs within process • Shares process environment • No context switch

  20. Platforms and Threading • Context switches expensive on Solaris, AIX • Context switches cheaper on Linux • Solaris uses M:N threading • Linux uses 1 process per thread • LinuxThreads implementation is old • Replaced by Native Posix Thread Library (NPTL) in 2.6 • NTPL already in RH 9, RHAS 3

  21. Thread-safety • Third-party modules and libraries • mod_perl: experimental threading in Perl 5.6; more mature in Perl 5.8 • PHP: uses many third-party libraries • FreeBSD: threading not reliable until 5.x • Apache 2.2 Worker MPM runs on FreeBSD

  22. MaxClients • Configuration file directive • Maximum number of workers • Apache 1.3, 2.0 Prefork: processes • Apache 2.0 Worker: threads * processes • Limit according to resources (memory)

  23. Sizing MaxClients • Take total RAM • Subtract OS allowance • look at free value without Apache, etc. • Subtract external program allowance • JVM, cgi programs, MySQL? • Divide by httpd process size • Read process size from top

  24. Top

  25. DNS Lookups • HostnameLookups • Access Control • Bad: Deny from example.com • Good: Deny from 172.160.234.5

  26. .htaccess Files • Per-directory configuration files • Accessed for every request • Best performance: AllowOverride none GET /dir1/dir2/restricted.html HTTP/1.0

  27. Server-side Includes • We Love Them! • Easy to implement • Easy to manage • We Hate Them! • They break sendfile() • They break cacheability • Use XBitHack Directive • Only parse executable text/html type files • Special treatment of Last-modified date

  28. SSI on www.apache.org SSI Enabled

  29. Tune your App Tier • Tomcat • Edit server.xml, tune minProcessors, maxProcessors • Use APR -> Persistent connections • Tune JVM (Heap, Garbage Collection) • MySQL • Ships with various scenarios in support-files: • my-{small,medium,large,huge}.conf • PHP & prefork: every child makes a connection • Tune max_connections variable in my.cnf

  30. System Tuning Tips • RAM and swap space • ulimit: files and processes • Turn off unused services and modules

  31. RAM and Swap • Swap is disk-based Extension of RAM • Excessive swapping kills performance • Tune MaxClients • Never have more memory than swap • Upgrade RAM -> add more swap space

  32. ulimit • Per-process resource limits • Built-in command of sh, bash • Important limits: • processes (-u) • open files (-n) • Set in invoking shell • Code in Apache 2 startup script • ulimit -S -n `ulimit -H -n` • Linux: /etc/security/limits.conf

  33. Caching Content • Dynamic Content is Expensive • Static Content Relatively Cheap • Several Approaches: • Dynamic caching • Pre-rendering popular pages (index.rss…)

  34. mod_cache Configuration <IfModule mod_cache.c> <IfModule mod_disk_cache.c> CacheRoot /raid1/cacheroot CacheEnable disk / # A page modified 100 min. ago will expire in 10 min. CacheLastModifiedFactor .1 # Always check again after 6 hours CacheMaxExpire 21600 </IfModule> </IfModule>

  35. Make Popular Pages Static • RSS Feeds • Popular catalog queries • … (Check your access log)

  36. Static Page Substitution <Directory "/home/sctemme/inst/blog/httpd/htdocs"> Options +Indexes Order allow,deny Allow from all RewriteEngine on RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule ^(.*)$ /cgi-bin/blosxom.cgi/$1 [L,QSA] </Directory>

  37. Tips • Observe Before You Act • Act on Monitoring Results • Don’t Overload Your System

  38. Q&A

  39. Conference Roadmap • TU1 30 Top PHP Scalability Mistakes • WE3 CNN.com Performance and Lessons Learned • WE8 Hacking the Apache HTTP Server at Yahoo! • WE24 Essentials on Performant JavaServer™ Faces Apps: Client Versus Server Side • TH1 Httpd Power Tools • TH4 mod_perl for Speed Freaks! • TH7 2.2 Rocks! Quit using 1.3 already! • TH9 mod_perl-2.0: Advanced Profiling & Instrumenting Techniques

  40. Current Version http://people.apache.org/~sctemme/ApconUS2006/WE18/

  41. Thank You

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