Introduction to APC
APC (alternative PHP cache) is a PHP buffer. It stores PHP pages in memory and reduces the I/O to the hard drive. This is obvious for performance improvement. You can even improve the performance of system 50% with a 50% reduction in CPU usage.
APC Extensions for installing PHP under Windows
Note: You cannot install both APC and Zend Optimiser on a single day server, only one of them can be selected.
Follow the instructions below to install the APC extension for PHP.
Download the correct version
I am using the PHP version is 5.3.10
Note: Make sure your version of the APC version you downloaded corresponds to your PHP edition.
set PHP.ini
Edit the php.ini file and add the following code to the Extension area section
Extension = Php_apc.dll
Reboot the server and use Phpinfo to see if the installation was successful
phpinfo ();
Phpinfo See if APC expansion has been successfully installed
to view available memory
Create a PHP file apcmeminfo.php
Print_r (Apc_sma_info ());
The amount of memory used by the cache is computed using this formula:
total_memory = apc.shm_segments * apc.shm_size
In this example, the available memory is about MB. Typically, if we need to exceed MB in our cache, we should increase the number of segments used by APC. However, this can cause Web server errors, so it is best to increase the size of the fragment. We should progressively increase the amount of usable total for the cache to avoid memory loss.
the default APC is as follows:
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Apc.cache_by_default = On
APC.ENABLE_CLI = Off
apc.enabled = On
Apc.file_update_protection = 2
Apc.filters =
Apc.gc_ttl = 3600
Apc.include_once_override = Off
Apc.max_file_size = 1M
Apc.num_files_hint = 1000
Apc.optimization = Off
Apc.report_autofilter = Off
Apc.shm_segments = 1
Apc.shm_size = 30
Apc.slam_defense = 0
Apc.stat = On
Apc.ttl = 0
Apc.user_entries_hint = 100
Apc.user_ttl = 0
Apc.write_lock = On
For an explanation of the complete parameter setting for APC, please refer to: HTTP://WWW.PHP.NET/APC.
The following is an APC block in a php.ini. Please paste them into your php.ini file:
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apc.enabled = 1
Apc.shm_segments = 1
Apc.shm_size = 64
Apc.max_file_size = 10M
Apc.stat=1
The remaining settings will use the default values.
Set up a temporary directory
APC requires a temporary directory to store files. It will attempt to cache files in Windows Temp directory, please write permissions to the temp directory beforehand.
Monitoring and tuning caching
monitoring and tuning APC cache
The APC source contains a PHP script that is useful for monitoring and tuning performance caching.
1, download APC Monitor file: HTTP://PECL.PHP.NET/PACKAGE/APC
2, the apc.php file in the package shows APC monitoring information.
3, run this file and you will see a graph showing your cache for some statistics.
4, tune the cache to view the general cache information and Detailed Memory Usage and Fragmentation sections (overall cache information and verbose memory usage and fragmentation).
5, monitor cache full count and percentage of fragments, if cache count is greater than 0, it means that caching is fully and reads frequently, because there is not enough memory to allocate. Adding apc.shm_size can solve the problem.
6, the fragment percentage should be 0%, but the value will rise as memory is read and write frequently.
the safety of apc.php
pay attention to the safety of apc.php, should use security authentication way to control apc.php information output, for example:
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Moodle user authentication
Require_once (".. /config.php ");
Require_once ($CFG--->libdir. /adminlib.php ');
Require_login ();
Require_capability (' Moodle/site:config ', get_context_instance (Context_system, SITEID));
Disable APC Auth (APC security certification)
Defaults (' Use_authentication ', 0);
//....
