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The Alternative PHP Cache install

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. from


Unpack your distribution file. You will have downloaded a file named something like apc_x.y.tar.gz. Unzip this file with a command like
# wget
# gunzip apc_x.y.tar.gz

Next you have to untar it with
#  tar xvf apc_x.y.tar

This will create an apc_x.y directory. cd into this new directory:
# cd apc_x.y

phpize is a script that should have been installed with PHP, and is normally located in /usr/local/php/bin assuming you installed PHP in /usr/local/php. (If you do not have the phpize script, you must reinstall PHP and be sure not to disable PEAR.).

Locate phpize:
# find / -name phpize

mine is in
yours may be in /usr/local/php/bin/phpize

Run the phpize command:
#  /usr/local/php/bin/phpize

Its output should resemble this:
        Configuring for:
          PHP Api Version:   20020918
          Zend Module Api No:   20020429
          Zend Extension Api No:   20021010

phpize should create a configure script in the current directory. If you get errors instead, you might be missing some required development tools, such as autoconf or libtool. You can try downloading the latest versions of those tools and running phpize again.

Run the configure script.

phpize creates a configure script. The only option you need to specify is the location of your php-config script.

find location of php-config
# find / -name php-config
# ./configure --enable-apc --enable-apc-mmap --with-apxs --with-php-config=/etc/alternatives/php-config

php-config should be located in the same directory as phpize.
If you prefer to use mmap instead of the default IPC shared memory support,  add --enable-apc-mmap to your configure line.

    If you prefer to use sysv IPC semaphores over the safer fcntl() locks, add –enable-sem to your configure line.  If you don’t have a problem
    with your server segaulting, or any other unnatural accumulation of semaphores on your system, the semaphore based locking is slightly faster.

Compile and install the files.
Simply type:
# make install
Installing shared extensions:     /usr/lib/php5/extensions/

Suggested Configuration (in your php.ini file)

Although the default APC settings are fine for many installations, serious
users should consider tuning the following parameters:

    OPTION                  DESCRIPTION
    ——————      ————————————————–
    apc.enabled             This 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 zend_extension
                            line can just be commented-out).
                            (Default: 1)

    apc.shm_segments        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.  Setting this to a
                            value other than 1 has no effect in mmap mode
                            since mmap’ed shm segments don’t have size limits.
                            (Default: 1)

    apc.shm_size            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.
                            (Default: 30)

    apc.optimization        This option has been deprecated.
                            (Default: 0)

    apc.num_files_hint      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.
                            (Default: 1000)

    apc.user_entries_hint   Just like num_files_hint, a "hint" about the number
                            of distinct user cache variables to store.
                            Set to zero or omit if you’re not sure;
                            (Default: 4096)

    apc.ttl                 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
                            (Default: 0)

    apc.user_ttl            The number of seconds a user 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
                            (Default: 0)

    apc.gc_ttl              The number of seconds that a cache entry may
                            remain on the garbage-collection list. This value
                            provides a failsafe 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.
                            (Default: 3600)

 apc.cache_by_default    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.
                            (Default: On)

    apc.filters             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.
                            (Default: "")

    apc.mmap_file_mask      If compiled with MMAP support by using –enable-mmap
                            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
                            something like /tmp/apc.XXXXXX (exactly 6 X’s).
                            To use POSIX-style shm_open/mmap put a ".shm"
                            somewhere in your mask.  eg.  "/apc.shm.XXXXXX"
                            You can also set it to "/dev/zero" to use your
                            kernel’s /dev/zero interface to anonymous mmap’ed
                            memory.  Leaving it undefined will force an
                            anonymous mmap.
                            (Default: "")

    apc.slam_defense        ** DEPRECATED – Use apc.write_lock instead **
                            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 this to 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 0 disables this
                            (Default: 0)

                            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 file_update_protection
                            setting puts a delay on caching brand new files.  The
                            default is 2 seconds which means that if the modification
                            timestamp (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.
                            (Default: 2)

    apc.enable_cli          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.
                            (Default: 0)

    apc.max_file_size       Prevents large files from being cached.
                            (Default: 1M)

    apc.stat                Whether to stat the main script file and the fullpath
                            includes.  If you turn this off you will need to restart

 apc.write_lock          On busy servers when you first start up the server, or when
                            many files are modified, you can end up with all your processes
                            trying to compile and cache the same files.  With write_lock
                            enabled, only one process at a time will try to compile an
                            uncached script while the other processes will run uncached
                            instead of sitting around waiting on a lock.
                            (Default: 1)

    apc.report_autofilter   Logs any scripts that were automatically excluded from being
                            cached due to early/late binding issues.
                            (Default: 0)

    apc.rfc1867             RFC1867 File Upload Progress hook handler is only available
                            if you compiled APC against PHP 5.2.0 or later.  When enabled
                            any file uploads which includes a field called
                            APC_UPLOAD_PROGRESS before the file field in an upload form
                            will cause APC to automatically create an upload_<key>
                            user cache entry where <key> is the value of the
                            APC_UPLOAD_PROGRESS form entry.

                            Note that the file upload tracking is not threadsafe at this
                            point, so new uploads that happen while a previous one is
                            still going will disable the tracking for the previous.
                            (Default: 0)

    apc.localcache          This enables a lock-free local process shadow-cache which
                            reduces lock contention when the cache is being written to.
                            (Default: 0)

    apc.localcache.size     The size of the local process shadow-cache, should be set to
                            a sufficently large value, approximately half of num_files_hint.
                            (Default: 512)

                            Optimize include_once and require_once calls and avoid the
                            expensive system calls used.
                            (Default: 0)


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