PHP Web Site Optimization

title

PHP Web Site Optimization

author

Greg Weir

PHP Web Site Optimization Training Materials

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What is Optimization? ⌘

• Reducing resource utilization
• Improving response time
  • Sometimes there is a tradeoff between the two, increasing utilization to reduce response time
• In this course, general techniques for any PHP application are covered
  • For some specialized applications, (e.g. WordPress) additional subject matter training is recommended

The Optimization Process ⌘

1. Create a well instrumented test
   1. Time metrics are absolutely required
   2. Some resource utilization metrics are needed, others may not be
   3. Re-using existing monitoring metrics is a good practice, but in some cases they may not be enough
2. Run the test (establish a baseline)
3. Make a change
   1. Identify possible sources of delay
   2. Make *one* change (e.g. optimize a SQL query, tweak a script, add cache, add hardware)
4. Repeat test and record results

Recommended Tools ⌘

• Apache JMeter - http://jmeter.apache.org/
  • Load testing tool, used to create and run tests
• xdebug - https://xdebug.org/
  • Debugging extension for PHP, with a built-in profiler for performance data
• Cachegrind GUI
  • Works with performance data generated by xdebug
  • Versions available for Linux, Windows, and MacOS

Opcode Caching ⌘

• This is built in to all versions of PHP since 5.5, by default
  • Same sort of optimization Zend previously offered in their Zend Optimizer product
• Parameters for the built-in caching are manipulated using the OPcache Module

Interprocess Communication ⌘

• IPC is any means of storing variables or sending signals between processes
  • Legacy forms of IPC in PHP applications:
    • Shared Memory (shmop)
    • Flat file
    • Temp tables in databases
  • Best practice forms of IPC:
    • memcached
    • Redis
    • ZeroMQ, RabbitMQ, beanstalkd
    • Gearman

Parallel Processing ⌘

• The problem: PHP is synchronous in nature, it is not designed for multithreading
• Ways of doing parallel processing:
  • curl_multi or sockets - OK for lower numbers of parallel operations
  • popen() or exec() - requires custom code but is relatively easy
  • Forking (pcntl_fork) - this is an advanced technique
  • Task queueing - essential for large scale, easier to dianose problems

Database Optimization ⌘

• Know how to turn on query logging and query caching
• Database basics: keys, joins, table scans, functions
• Optimizing a known query
  • Look at each table involved (MySQL: DESCRIBE tbl_name, Postgres: \d+ tbl_name)
  • EXPLAIN - Available in MySQL and PostgreSQL
  • Can the query use existing keys better?
  • If there is a subquery, can we reduce or reuse it?
  • Are we retrieving columns we don't need?
  • Can we create a key to help improve the query?