• MemcachedExample

• BinaryTreeExample

Tools Boxaroo used

• dBug
• stack trace - customized
• poor man's profiling
• wanted to use xDebug but was never critical

Compilation

• configure with –-enable-inline-optimization
• Compile with -O3, -march, -msse3, -mfpmath=sse, -funroll-loops
• Compile only essential modules, rarely used ones as shared objs for scripts that need them
• Compile statically into Apache (up to 20% gain)
  • PHP: ./configure --with-apache=/path/to/apache_source
  • Apache: ./configure --activate-module=src/modules/php4/libphp4.a
• strip symbols out (saves 20-30%)

Config

• Disable...
  • magic_quotes_* directives. (but be extra careful with escaping)
  • Turn off expose_php
  • Turn off register_argc_argv for non-cli SAPIs
  • Unless absolutely necessary do not enable always_populate_raw_post_data
• Put php.ini where PHP will look first
• hdparm
• compress ob_start("ob_gzhandler");

Apache

• StartServers to avg simult. requests expected
• MaxSpareServers set high to handle spikes
• MaxClients ~2/5 max processes server can handle
• MaxRequestsPerChild ideally unlimited (0) but realistically a large number
• Avoid mod_rewrite if possible
• Tune logging setup
• Use IPs, not names for Deny/Allow rules
• Carefully set KeepAlive and KeepAliveTimeout to avoid crippling the server yet not to waste reconnection overhead - though probably disable for PHP / dynamic pages
• look into using lingerd to manage TCP stuff after page has been sent
• Use one group of servers just for static / css stuff; use another for dynamic - different tuning parameters
• Tux / thttpd

Coding tricks

• Compression - 10% CPU load, lower B/W
• CSS - 20-30% smaller pages than old HTML (esp tables)
• tidy extension, though CPU expensive, worth it maybe if cached
• Always use full path for include, esp with opcode cache
• Sometimes worth it to force type conversion
• watch for funcs (e.g. sizeof) being part of a loop construct! Eval'd each iteration!
• initialize variables! Incrementing undefined local 9-10x slower than pre-initialized one.
• methods in derived classes run faster than ones in the base class
• Replace regexps with normal string processing if possible. PCRE (perl compat) faster than ereg.
• Regexp's can be faster than DOM for XML parsing

Sessions

• Use RAM disk
• Implement your own session reader/writer like we did. Maybe to RAM disk. Or (?) mmcache
• enable shared memory (configure --with-mm), session.save_handler=mm in php.ini

Caching

• Tuck MMCache - like Zend - Using mmcache_cache_output(file, ???func???, ttl);
• Pear Cache
• Cache-lite (newer, more recommended)

Tuning / Benchmarking

• ab - Apachebench
  • =ab -n1000 -c10 http://192.168.0.99/php/testmysql.php= : 1000 requests, 10 simultaneous connections
• flood
• vmstat 1
• microtime()
• when load avg > # of procs, system is overloaded! In vmstat/top it's 1 / 5 / 15 mins
• In top, R = runnable, S = sleeping, W = swapped out

SQL

• Adodb might be faster than the built-in database abstraction system
• Use explain before queries to identify slow ones - queries not using keys
• Query chaining (separation by is faster
• Watch lock usage
  • Row level better than table level (try!)
• Joins just might be slower since there's a read lock on all tables involved
• Use non-persistent database connections to avoid running out of Mysql max # connections
• (try!) doing a temp table

mysql_query("CREATE TEMPORARY TABLE mtmp AS 
    SELECT id FROM msg WHERE 
        thread_id={$_GET['th']} AND apr=1 
        ORDER BY id ASC LIMIT {$count}, {$_GET['start']}");

// Retrieve needed data by using the temporary table as base
$result = mysql_query("SELECT * FROM mtmp mt
        INNER JOIN msg m ON m.id=mt.id
        INNER JOIN thread t ON m.thread_id=t.id
        INNER JOIN forum f ON t.forum_id=f.id
        LEFT JOIN users u ON m.poster_id=u.id
        LEFT JOIN level l ON u.level_id=l.id
        LEFT JOIN poll p ON m.poll_id=p.id
        LEFT JOIN poll_opt_track pot ON pot.poll_id=p.id 
            AND pot.user_id="._uid." 
        ORDER BY m.id ASC");

-- MattWalsh - 23 Oct 2008