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Date: Thu, 12 Nov 2009 11:54:55 -0800
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To: Basant Kukreja <basant.kukreja@gmail.com>
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Subject: Re: [PHP-DEV] open/close calls of include_once/require_once files.
From: rasmus@lerdorf.com (Rasmus Lerdorf)

A couple of notes.

You make it sound like this happens on all includes.  It is only
include_once/require_once that have this problem.  Regular
include/require do not.

This has been addressed in APC by overriding the opcode and providing
our own opcode handler for this case.  See
http://svn.php.net/viewvc/pecl/apc/trunk/apc_zend.c?view=markup&pathrev=289331
line 86.

Having said that, it would be preferable, of course, if we didn't need
to swap out that code in APC but I am not sure your solution for solving
this only for absolute path includes is the right way to go here.

-Rasmus

Basant Kukreja wrote:
> Hi, 
>     When php script includes a script,  php engine compiles the included file.
> When opcode caching extensions e.g apc are used, re-compilation is avoided by
> apc. But there is a performance problem here. Since php code uses
> zend_stream_open to open the included file, open/close system call is still
> there. When used with APC, open/close doesn't do any good for file-system based
> files. It only provides the realpath of the opened file. In php 5.3,
> zend_resolve_path already provides the realpath of the file being opened so we
> can avoid an open/close calls for file to be included if file is an absolute
> path.
> 
> Current php 5.3 implementation for include_once/require_once (pseudo code)
> 
> a) call zend_resolve_path. It will provide the realpath. Symlinks are taken
> care of by zend_resolve_path.
> b) Check if file is already included. If yes, do nothing else go to step (c)
> c) Call zend_stream_open and get the included_file realpath.
> d) Invoke zend_compile_file and do the rest.
> 
> Now zend_stream_open invokes the open/close calls to the including files which
> is redundant when caches are used.
> 
> Here is the suggested performance fix :
> a) Same as previous
> b) Same as previous
> c) If resolved_path is an absolute path then do step c.1 else do c.2
> c.1) Prepare a file_handle and directly invoke zend_compile_file
> c.2 Call zend_stream_open and get the included_file realpath.
> b) Same as previous
> 
> ---------------------------------------------------
> 
> Few notes :
> * Performance improvements using this patch = ~1.5% in an e-commerce workload.
> * Testing : I ran the php 5.3 test suite and didn't find any regression.
> * If files which are included are not absolute paths then they will follow
>   the same zend_stream_path route.
> * Tested with symlinks and found the behaviour is expected (no change).
> 
> I have attached the patch for review comments.
> 
> Regards,
> Basant.
> 
> Note: I previously did this work for php 5.2 but bug remains still open. 5.3
> implementation is relatively straight forward. Here is the reference to 5.2 bug
> : http://bugs.php.net/bug.php?id=47660&thanks=2
> 
> 
>