Apache Performance Tuning Part 1 Scaling Up Sander

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

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 10 Mbits of outgoing bandwidth, which Apache can fill using only a low end Pentium-based webserver. ” 2

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

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

Monitoring Your Server 6

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

Monitoring Apache 8

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

Other Monitoring Tools • • 10 vmstat iostat top free

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Web Server Logs • Error. Log • Log. Level: debug, info, notice, warn, error, crit • Access Log: Transfer. Log or Custom. Log • Common Log Format 12

Common Log Format 172. 16. 2. 91 13 - - [16/Nov/2003: 15: 23: 27 [16/Nov/2003: 15: 23: 28 [16/Nov/2003: 15: 23: 29 [16/Nov/2003: 15: 23: 34 -0800] -0800] "GET "GET /~sctemme/ HTTP/1. 1" 200 1446 /~sctemme/css/doc. css HTTP/1. 1" 200 167 /~sctemme/css/menu. css HTTP/1. 1" 200 623 /favicon. ico HTTP/1. 1" 404 283 /~sctemme/index. html HTTP/1. 1" 200 1446 Client IP 172. 16. 2. 91 RFC 1413 ident - username - timestamp [16/Nov/2003: 15: 23: 29 -0800] Request "GET /favicon. ico HTTP/1. 1" Status Code 404 Content Bytes 283

Configuring for Performance • Configuring Apache • Tuning the Operating System 14

Apache Configuration • • • 15 Process/Thread Management DNS Lookups Avoid. htaccess Files Disable unused modules Tune your App Tier

DNS Lookups • Hostname. Lookups • Access Control • Bad: Deny from example. com • Good: Deny from 172. 160. 234. 5 16

. htaccess Files • Per-directory configuration files • Accessed for every request • Best performance: Allow. Override none GET /dir 1/dir 2/restricted. html HTTP/1. 0 17

Max. Clients • • • 18 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)

Server-side Includes • We Love Them! • Easy to implement • Easy to manage • We Hate Them! • They break sendfile() • They break cacheability 19

SSI on www. apache. org SSI Enabled 20

Sizing Max. Clients • Take total RAM • Subtract OS allowance • look at free value without Apache, etc. • Subtract external program allowance • JVM, cgi programs, My. SQL? • Divide by httpd process size • Read process size from top 21

Top 22

Selecting Your MPM • • 23 Apache 2. 0 only! Processes and Threads Differences between platforms Thread-safety issues

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 24

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 Linux. Threads implementation is old • Replaced by Native Posix Thread Library (NPTL) in 2. 6 • NTPL already in RH 9, RHAS 3 25

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 • Free. BSD: threading not reliable until 5. x • Apache 2. 2 Worker MPM runs on Free. BSD 26

Tune your App Tier • Tomcat • Edit server. xml, tune min. Processors, max. Processors • Use APR -> Persistent connections • Tune JVM (Heap, Garbage Collection) • My. SQL • 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 27

System Tuning Tips • RAM and swap space • ulimit: files and processes • Turn off unused services and modules 28

RAM and Swap • • Swap is disk-based Extension of RAM Excessive swapping kills performance Tune Max. Clients Never have more memory than swap • Upgrade RAM -> add more swap space 29

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. 0 startup script • ulimit -S -n `ulimit -H -n` • Linux: /etc/security/limits. conf 30

Caching Content • Dynamic Content is Expensive • Static Content Relatively Cheap • Several Approaches: • Dynamic caching • Pre-rendering popular pages (index. rss…) 31

mod_cache Configuration <If. Module mod_cache. c> <If. Module mod_disk_cache. c> Cache. Root /raid 1/cacheroot Cache. Enable disk / # A page modified 100 min. ago will expire in 10 min. Cache. Last. Modified. Factor. 1 # Always check again after 6 hours Cache. Max. Expire 21600 </If. Module> 32

Make Popular Pages Static • RSS Feeds • Popular catalog queries • … (Check your access log) 33

Static Page Substitution <Directory "/home/sctemme/inst/blog/httpd/htdocs"> Options +Indexes Order allow, deny Allow from all Rewrite. Engine on Rewrite. Cond %{REQUEST_FILENAME} !-f Rewrite. Cond %{REQUEST_FILENAME} !-d Rewrite. Rule ^(. *)$ /cgi-bin/blosxom. cgi/$1 [L, QSA] </Directory> 34

Tips • Observe Before You Act • Act on Monitoring Results • Don’t Overload Your System 35

Q&A

Conference Roadmap • • 37 TH 9: Building a Fast and Rich Web App with PHP 5 TH 10: Troubleshooting Apache configurations TH 19: mod_perl for Speed Freaks! TH 22: Garbage collection tuning for java server processes FR 12: Getting everything out of Apache Derby database FR 1: Scaling httpd 2. x to 50, 000 Concurrent Downloads FR 5: Apache Performance Tuning Part 2: Scaling Out FR 24: PHP and My. SQL Best Practices 2. 0

Current Version http: //people. apache. org/~sctemme/Apcon. EU 2006/FR 4/

Thank You