Shoehorning Apache Onto Your Box

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Shoehorning Apache Onto Your Box

• System Sizing Tips

Sander Temme ltsander_at_temme.netgt
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So, your web server machine may not be the
fastest, shiniest machine,but it can still take
a few hits without going down.
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Assumptions

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

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Purposes of Monitoring

• Observation
• Extrapolation
• Signals/Alerts
• Testing

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Monitoring Your Server
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Monitoring Apache
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Monitoring Nagios
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Other Monitoring Tools

• vmstat
• top
• free

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Web Server Logs

• ErrorLog
• LogLevel debug, info, notice, warn, error, crit
• Access Log TransferLog or CustomLog
• Common Log Format

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Common Log Format
172.16.2.91 - - 16/Nov/2003152327 -0800 "GET
/sctemme/ HTTP/1.1" 200 1446 172.16.2.91 - -
16/Nov/2003152328 -0800 "GET
/sctemme/css/doc.css HTTP/1.1" 200
167 172.16.2.91 - - 16/Nov/2003152328 -0800
"GET /sctemme/css/menu.css HTTP/1.1" 200
623 172.16.2.91 - - 16/Nov/2003152329 -0800
"GET /favicon.ico HTTP/1.1" 404 283 172.16.2.91 -
- 16/Nov/2003152334 -0800 "GET
/sctemme/index.html HTTP/1.1" 200 1446
Client IP 172.16.2.91
RFC 1413 ident -
username -
timestamp 16/Nov/2003152329 -0800
Request "GET /favicon.ico HTTP/1.1"
Status Code 404
Content Bytes 283
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Configuring for Performance

• Configuring Apache
• Tuning the Operating System
• Scaling Your Site

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Apache Configuration

• Process/Thread Management
• DNS Lookups
• Avoid .htaccess Files
• Disable unused modules
• Tune your App Tier
• Cache if you Can

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DNS Lookups

• HostnameLookups
• Access Control
• Bad Deny from example.com
• Good Deny from 172.160.234.5

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.htaccess Files

• Per-directory configuration files
• Accessed for every request
• Best performance AllowOverride none

GET /dir1/dir2/restricted.html HTTP/1.0
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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)

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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

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Top
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Tune your App Tier

• Tomcat
• Edit server.xml, tune minProcessors,
  maxProcessors
• 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

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Cache your Content

• Dynamic Content is Expensive
• Static Content is Cheap
• Dont Regenerate the Same Page
• Cache it!
• Wiki, Blog, Catalogs,
• Example wiki.apache.org

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System Tuning Tips

• RAM and swap space
• ulimit files and processes
• Turn off unused services and modules
• Patch your OS

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RAM and Swap

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

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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

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Example ajax.apache.org

• 4xItanium CPU HP Integrity Server, 8Gb RAM
• RHEL 3.0
• www.apache.org, most TLPs, JIRA, Bugzilla, Wiki
• Very beefy machine
• Does not perform well
• Especially disk access
• Upgrade to RHEL 4.0? (future)
• JIRA Upgrade Helped
• Cache for Wiki Helped
• Wiki under mod_pyton? (future?)

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Scaling Your Site

• Vertically
• Tiered Model
• Horizontally
• Load Balancing

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Scaling Vertically
TCP/IP
Client
TCP/IP
TCP/IP
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Scaling Vertically

• Move Services to Other Hosts
• Pros
• Less resource contention
• Specialized hardware
• Scale tiers individually
• Cons
• Development/Deployment harder
• More hosts to manage

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Scaling Horizontally
Client
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Tips

• Observe Before You Act
• Act on Monitoring Results
• Dont Overload Your System
• Use A Staging Server

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QA
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Further Reading

• Ryan B. Bloom, Apache Server 2.0 The Complete
  Reference, 2002 McGraw Hill Osborne ISBN
  0-07-222344-8
• Ben Laurie and Peter Laurie, Apache The
  Definitive Guide (3rd Edition), 2002 OReilly
  Associates ISBN 0596002033
• Patrick Killelea, Web Performance Tuning, 2nd
  Edition, 2002 OReilly Associates ISBN
  0-596-00172-X
• http//httpd.apache.org/docs-2.0/misc/perf-tuning.
  html
• http//httpd.apache.org/docs/misc/perf-tuning.html
  
• Adrian Cockcroft, Richard Pettit and Sun
  Microsystems Press, Sun Performance and Tuning
  Java and the Internet (2nd Edition), 1998
  Prentice Hall PTR ISBN 0130952494
• Ken Coar and Rich Bowen, Apache Cookbook, 2003
  OReilly Associates ISBN 0596001916

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Conference Roadmap

• T20 Scalable Internet Architectures
• WE04 QoS management of Internet services
• WE09 Troubleshooting Apache configurations
• TH01 Scaling Apache 2.x to gt 20,000 concurrent
  downloads
• TH17 Caching, Tips for Improving Performance
• TH21 Powering High-volume web sites with
  Lenya/Cocoon and mod_cache
• FR05 Improving Web Performance with Dynamic
  Compression
• FR09 Clustering and load balancing using
  mod_proxy

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Current Version

• http//apache.org/sctemme/ApconEU2005/WE05/

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Thank You
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Backup Slides
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Selecting Your MPM

• Apache 2.0 only!
• Processes and Threads
• Differences between platforms
• Thread-safety issues

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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

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Platforms and Threading

• Context switches expensive on Solaris, AIX
• Context switches cheaper on Linux
• Solaris uses MN 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

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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
• Use KSE threading in 5.x
• Still not endorsed by ASF