PHP如何通过开启Opcache来提高性能

在开启Opcache之前,我们先了解一下什么是Opcache:

OPcache 通过将 PHP 脚本预编译的字节码存储到共享内存中来提升 PHP 的性能, 存储预编译字节码的好处就是 省去了每次加载和解析 PHP 脚本的开销。
PHP 5.5.0 及后续版本中已经绑定了 OPcache 扩展。 对于 PHP 5.2,5.3 和 5.4 版本可以使用 » PECL 扩展中的 OPcache 库。

下面来说说如何安装Opcache,不同的PHP版本安装的方法稍有不同:

OPcache 只能编译为共享扩展。 如果你使用 --disable-all 参数 禁用了默认扩展的构建, 那么必须使用 --enable-opcache 选项来开启 OPcache。
编译之后,就可以使用 zend_extension 指令来将 OPcache 扩展加载到 PHP 中。在非 Windows 平台使用 zend_extension=/full/path/to/opcache.so,
Windows平台使用 zend_extension=C:\path\to\php_opcache.dll

PHP 5.2,5.3和 5.4版本中没有和PHP捆绑,需要自行安装,这里不做说明。

官方出了一个推荐配置如下:

使用下列推荐设置来获得较好的 性能:

opcache.memory_consumption=128
opcache.interned_strings_buffer=8
opcache.max_accelerated_files=4000
opcache.revalidate_freq=60
opcache.fast_shutdown=1
opcache.enable_cli=1
你也可以禁用 opcache.save_comments 并且启用 opcache.enable_file_override。 需要提醒的是,在生产环境中使用上述配置之前,必须经过严格测试。 因为上述配置存在一个已知问题,它会引发一些框架和应用的异常, 尤其是在存在文档使用了备注注解的时候。

配置扩展的时候注意以下问题

在php.ini中增加opcache时需要使用zend_extension,而不是extension,不然会得到以下WARNING

PHP Warning: PHP Startup: Invalid library (appears to be a Zend Extension, try loading using zend_extension=opcache.so from php.ini) in Unknown on line 0

由于我自己的服务器安装的PHP7,已经安装了Opcache,所以我只需在php.ini文件中配置以下内容

zend_extension=/usr/local/php/lib/php/extensions/no-debug-non-zts-20151012/opcache.so

[opcache]

;开关打开
opcache.enable=1
;设置共享内存大小, 单位为:Mb
opcache.memory_consumption=128
opcache.interned_strings_buffer=8
opcache.max_accelerated_files=4000
opcache.revalidate_freq=60
opcache.fast_shutdown=1
opcache.enable_cli=1

本次涉及到的有两个参数

revalidate_freq,默认2
检查脚本时间戳是否有更新的周期,以秒为单位。 设置为 0 会导致针对每个请求, OPcache 都会检查脚本更新

validate_timestamps,默认1
如果启用,那么 OPcache 会每隔 opcache.revalidate_freq 设定的秒数 检查脚本是否更新。 如果禁用此选项,你必须使用 opcache_reset() 或者 opcache_invalidate() 函数来手动重置 OPcache,也可以 通过重启 Web 服务器来使文件系统更改生效。

最后重启Nginx和PHP即可

下面是OPcache 可用的配置指令完整列表:

; Determines if Zend OPCache is enabled
;opcache.enable=0

; Determines if Zend OPCache is enabled for the CLI version of PHP
;opcache.enable_cli=0

; The OPcache shared memory storage size.
;opcache.memory_consumption=64

; The amount of memory for interned strings in Mbytes.
;opcache.interned_strings_buffer=4

; The maximum number of keys (scripts) in the OPcache hash table.
; Only numbers between 200 and 1000000 are allowed.
;opcache.max_accelerated_files=2000

; The maximum percentage of "wasted" memory until a restart is scheduled.
;opcache.max_wasted_percentage=5

; When this directive is enabled, the OPcache appends the current working
; directory to the script key, thus eliminating possible collisions between
; files with the same name (basename). Disabling the directive improves
; performance, but may break existing applications.
;opcache.use_cwd=1

; When disabled, you must reset the OPcache manually or restart the
; webserver for changes to the filesystem to take effect.
;opcache.validate_timestamps=1

; How often (in seconds) to check file timestamps for changes to the shared
; memory storage allocation. ("1" means validate once per second, but only
; once per request. "0" means always validate)
;opcache.revalidate_freq=2

; Enables or disables file search in include_path optimization
;opcache.revalidate_path=0

; If disabled, all PHPDoc comments are dropped from the code to reduce the
; size of the optimized code.
;opcache.save_comments=1

; If enabled, a fast shutdown sequence is used for the accelerated code
; Depending on the used Memory Manager this may cause some incompatibilities.
;opcache.fast_shutdown=0

; Allow file existence override (file_exists, etc.) performance feature.
;opcache.enable_file_override=0

; A bitmask, where each bit enables or disables the appropriate OPcache
; passes
;opcache.optimization_level=0xffffffff

;opcache.inherited_hack=1
;opcache.dups_fix=0

; The location of the OPcache blacklist file (wildcards allowed).
; Each OPcache blacklist file is a text file that holds the names of files
; that should not be accelerated. The file format is to add each filename
; to a new line. The filename may be a full path or just a file prefix
; (i.e., /var/www/x  blacklists all the files and directories in /var/www
; that start with 'x'). Line starting with a ; are ignored (comments).
;opcache.blacklist_filename=

; Allows exclusion of large files from being cached. By default all files
; are cached.
;opcache.max_file_size=0

; Check the cache checksum each N requests.
; The default value of "0" means that the checks are disabled.
;opcache.consistency_checks=0

; How long to wait (in seconds) for a scheduled restart to begin if the cache
; is not being accessed.
;opcache.force_restart_timeout=180

; OPcache error_log file name. Empty string assumes "stderr".
;opcache.error_log=

; All OPcache errors go to the Web server log.
; By default, only fatal errors (level 0) or errors (level 1) are logged.
; You can also enable warnings (level 2), info messages (level 3) or
; debug messages (level 4).
;opcache.log_verbosity_level=1

; Preferred Shared Memory back-end. Leave empty and let the system decide.
;opcache.preferred_memory_model=

; Protect the shared memory from unexpected writing during script execution.
; Useful for internal debugging only.
;opcache.protect_memory=0

; Allows calling OPcache API functions only from PHP scripts which path is
; started from specified string. The default "" means no restriction
;opcache.restrict_api=

; Mapping base of shared memory segments (for Windows only). All the PHP
; processes have to map shared memory into the same address space. This
; directive allows to manually fix the "Unable to reattach to base address"
; errors.
;opcache.mmap_base=

; Enables and sets the second level cache directory.
; It should improve performance when SHM memory is full, at server restart or
; SHM reset. The default "" disables file based caching.
;opcache.file_cache=

; Enables or disables opcode caching in shared memory.
;opcache.file_cache_only=0

; Enables or disables checksum validation when script loaded from file cache.
;opcache.file_cache_consistency_checks=1

; Implies opcache.file_cache_only=1 for a certain process that failed to
; reattach to the shared memory (for Windows only). Explicitly enabled file
; cache is required.
;opcache.file_cache_fallback=1

; Enables or disables copying of PHP code (text segment) into HUGE PAGES.
; This should improve performance, but requires appropriate OS configuration.
;opcache.huge_code_pages=0

; Validate cached file permissions.
; opcache.validate_permission=0

; Prevent name collisions in chroot'ed environment.
; opcache.validate_root=0

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