The Alternative PHP Cache (APC) is a free and open opcode cache for PHP. It was conceived of to provide a free, open, and robust framework for caching and optimizing PHP intermediate code.
本 » PECL 扩展未绑定于 PHP 中。
进一步信息例如新版本，下载，源程序，维护者信息以及更新日志可以在此找到： » http://pecl.php.net/package/apc.
On Windows, APC expects
c:\tmp to exist, and be
writable by the web server.
For more in-depth, highly technical documentation, see the » developer-supplied TECHNOTES file .
Although the default APC settings are fine for many installations, serious users should consider tuning the following parameters.
|apc.enable_cli||"0"||PHP_INI_SYSTEM||> APC 3.0.6|
有关 PHP_INI_* 常量进一步的细节与定义参见附录 G,
apc.enabled can be set to 0 to disable APC. This is
primarily useful when APC is statically compiled
into PHP, since there is no other way to disable
it (when compiled as a DSO, the
php.ini can just be commented-out).
The number of shared memory segments to allocate
for the compiler cache. If APC is running out of
shared memory but you have already set
apc.shm_size as high as your system allows, you
can try raising this value.
The size of each shared memory segment in MB. By default, some systems (including most BSD variants) have very low limits on the size of a shared memory segment.
The optimization level. Zero disables the optimizer, and higher values use more aggressive optimizations. Expect very modest speed improvements. This is experimental.
A "hint" about the number of distinct source files that will be included or requested on your web server. Set to zero or omit if you're not sure; this setting is mainly useful for sites that have many thousands of source files.
The number of seconds a cache entry is allowed to idle in a slot in case this cache entry slot is needed by another entry. Leaving this at zero means that your cache could potentially fill up with stale entries while newer entries won't be cached.
The number of seconds that a cache entry may remain on the garbage-collection list. This value provides a fail-safe in the event that a server process dies while executing a cached source file; if that source file is modified, the memory allocated for the old version will not be reclaimed until this TTL reached. Set to zero to disable this feature.
On by default, but can be set to off and used in
conjunction with positive
apc.filters so that files
are only cached if matched by a positive filter.
A comma-separated list of POSIX extended regular
expressions. If any pattern matches the source
filename, the file will not be cached. Note that
the filename used for matching is the one passed
to include/require, not the absolute path. If the
first character of the expression is a
+ then the
expression will be additive in the sense that any
files matched by the expression will be cached, and
if the first character is a
- then anything matched
will not be cached. The
- case is the default, so
it can be left off.
If compiled with MMAP support by using
this is the mktemp-style file_mask to pass to the
mmap module for determing whether your mmap'ed memory
region is going to be file-backed or shared memory
backed. For straight file-backed mmap, set it to
To use POSIX-style shm_open/mmap put a
somewhere in your mask. e.g.
You can also set it to
/dev/zero to use your
/dev/zero interface to anonymous mmap'ed
memory. Leaving it undefined will force an anonymous mmap.
On very busy servers whenever you start the server or
modify files you can create a race of many processes
all trying to cache the same file at the same time.
This option sets the percentage of processes that will
skip trying to cache an uncached file. Or think of it
as the probability of a single process to skip caching.
For example, setting
75 would mean that there is
a 75% chance that the process will not cache an uncached
file. So, the higher the setting the greater the defense
against cache slams. Setting this to
disables this feature.
When you modify a file on a live web server you really
should do so in an atomic manner. That is, write to a
temporary file and rename (
mv) the file into its
permanent position when it is ready. Many text editors, cp, tar and
other such programs don't do this. This means that there
is a chance that a file is accessed (and cached) while it
is still being written to. This
setting puts a delay on caching brand new files. The
default is 2 seconds which means that if the modification
mtime) on a file shows that it is less than 2
seconds old when it is accessed, it will not be cached.
The unfortunate person who accessed this half-written file
will still see weirdness, but at least it won't persist.
If you are certain you always atomically update your files
by using something like rsync which does this correctly, you
can turn this protection off by setting it to 0. If you
have a system that is flooded with io causing some update
procedure to take longer than 2 seconds, you may want to
increase this a bit.
Mostly for testing and debugging. Setting this enables APC for the CLI version of PHP. Normally you wouldn't want to create, populate and tear down the APC cache on every CLI request, but for various test scenarios it is handy to be able to enable APC for the CLI version of APC easily.