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litespeed_wiki:php:opcode_cache [2014/05/22 13:39] Michael Armstrong |
litespeed_wiki:php:opcode_cache [2018/09/14 15:56] (current) Michael Alegre [Opcode caching limitations] |
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| ====== PHP Opcode Caching: General Overview ====== | ====== PHP Opcode Caching: General Overview ====== | ||
| - | One advantage of LiteSpeed Web Server is that it allows for effective use of opcode caching with shared hosting. This wiki will cover the basics of opcode caching — what it does and its limitations. We recommend this wiki for users who are new to opcode caching. | + | LiteSpeed Web Server allows for effective use of opcode caching with shared hosting. Because Apache does not provide this capability, new LSWS users may want a brief introduction to opcode caching. This wiki will cover the basics of opcode caching — what it does, its limitations, and popular opcode caches. |
| ===== What is opcode caching? ===== | ===== What is opcode caching? ===== | ||
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| ===== Opcode caching limitations ===== | ===== Opcode caching limitations ===== | ||
| - | - **Opcode caching requires extra RAM.** The RAM limit you set for opcode caching will be automatically partitioned off. You will lose access to this RAM for other uses, so do not allow opcode caching to use too much of your RAM. | + | - **Opcode caching requires extra RAM.** The RAM limit you set for opcode caching will be automatically partitioned off. You will lose access to this RAM for other uses, so do not allow opcode caching to use too much of your RAM. For example, for a plesk user, normally 128M memory was allowed for that account. opcode cache should be set to 32M or lower. We did see out of memory error when opcode cache memory set to 64M. |
| - | - **Opcode caching requires PHP processes be forked from the same parent process in order to share the cache.** If the process is killed, the cache is flushed. This is why opcode caching does not work well with Apache's suPHP -- suPHP starts a new process for each PHP process, causing opcode cache to be flushed almost as soon as it was created. LiteSpeed's [[http://www.litespeedtech.com/products/litespeed-sapi/php/suexec-daemon-mode|suEXEC Daemon mode]] and [[http://www.litespeedtech.com/products/litespeed-sapi/php/suexec-processgroup|suEXEC ProcessGroup]] have been developed for greater use of opcode caching with PHP suEXEC. | + | - **Opcode caching requires PHP processes be forked from the same parent process in order to share the cache.** If the parent process is killed, the cache is flushed. This is why opcode caching does not work well with Apache's suPHP -- suPHP starts a new process for each PHP process, causing opcode cache to be flushed almost as soon as it was created. LiteSpeed's [[http://www.litespeedtech.com/products/litespeed-sapi/php/suexec-daemon-mode|Daemon mode]] and [[http://www.litespeedtech.com/products/litespeed-sapi/php/suexec-processgroup|ProcessGroup mode]] have been developed for greater use of opcode caching with PHP suEXEC while default Worker mode does not. Please [[litespeed_wiki:php:enable_opcode_cache|make a change]] during opcode enabling process. |
| - **Opcode caches can be buggy.** Many users find that choosing an opcode cache is a matter of trial and error -- different opcode caches work better in different setups. | - **Opcode caches can be buggy.** Many users find that choosing an opcode cache is a matter of trial and error -- different opcode caches work better in different setups. | ||
| + | - **Opcode caches can cause 503 errors.** This is an extension of the previous point. Opcodes caches are a frequent cause of 503 errors. Try turning off your opcode cache if you're getting 503 errors. | ||
| ===== Popular Opcode Caches ===== | ===== Popular Opcode Caches ===== | ||
| - | * [[http://pecl.php.net/package/APC|APC (Alternative Opcode Cache)]] -- Supports PHP 5.4 and earlier. | + | |
| - | * [[http://eaccelerator.net/|eAccelerator]] -- Supports PHP 5.4 and 5.5. (Possibly dead.) | + | * [[http://pecl.php.net/package/ZendOpcache|Zend Opcache]] -- Actively maintained and supports PHP 5.2 and up. Starting from PHP 5.5,including 7.0, it is bundled with PHP main source code. |
| - | * [[http://xcache.lighttpd.net/|xCache]] -- Supports all PHP versions. | + | * [[litespeed_wiki:php:apc|APC (Alternative Opcode Cache)]] -- Appears to be discontinued. Supports PHP up to version 5.4, but has been reported buggy with PHP 5.4. May be a good solution for PHP 5.3. APC has opcode cache as well as user/variable cache. Since PHP 5.5 and PHP 5.6 are unsupported by APC, xCache or Zend Opcache can be alternatives for op-code cache while APCu could be alternative to APC's user cache. |
| - | * [[http://pecl.php.net/package/ZendOpcache|Zend Opcache]] -- Supports PHP 5.2 and up. | + | * [[http://xcache.lighttpd.net/|xCache]] -- Actively maintained and supports most PHP versions upto 5.6 but not 7.0. |
| + | * [[http://eaccelerator.net/|eAccelerator]] -- Dead project. Supported PHP 5.4 and earlier. | ||
| + | |||
| + | How to enable opcode caches? Please check [[litespeed_wiki:php:enable_opcode_cache|here]]. | ||