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Date:  Thu, 12 Jul 2007 11:51:36 +0200
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Subject:  Re: [PHP-DEV] Mid-term Update for Cycle Collector (Google Summer
 of Code Project)
From: sb@sebastian-bergmann.de (Sebastian Bergmann)

David Wang schrieb:
> Hello, everyone. My name is David Wang and I am one of the students
> participating in Google Summer of Code this year. As you may remember,
> my project is to implement a garbage collector for circular references
> in PHP. As the midterm for Summer of Code is coming up, my mentor,
> Derick Rethans, thought it would be a good idea if I shared my
> progress with the community.

 Hello David,

> On the Graph test, maximum memory usage with unmodified PHP was 133.9
> MB with an execution time of 8 seconds.
> On the Graph test, maximum memory usage with gc was 51.6 MB with an
> execution time of 9 seconds.
> On the Template test, maxmium memory usage with unmodified PHP was 1.5
> GB with an execution time of 30 seconds.
> On the Template test, maxmium memory usage with gc was 67.3 MB with an
> execution time of 1 minute.
> On the whole suite of tests (which includes the Graph and Template
> tests), execution time with unmodified PHP was 12:03. With cycle
> collection, it was 12:43.

 these numbers are quite impressive.

> My project is currently being hosted on the xdebug CVS. You can get
> the latest version with the following commands:
> 
> cvs -d :pserver:srmread@cvs.xdebug.org:/repository login
> CVS password: srmread
> cvs -d :pserver:srmread@cvs.xdebug.org:/repository co circular
> Note that I'm implementing my project on top of a CVS version of PHP
> 5.2 that is a couple of weeks old. However, the cycle collector can be
> ported into other versions of PHP fairly easily as it does not affect
> the existing Zend engine code too much.

 As a first step, I think the code changes that convert direct accesses
 to the reference counters to the proper macros should be merged. These
 changes should be done in any case and it minimizes your patch and makes
 it more readable.

-- 
Sebastian Bergmann                          http://sebastian-bergmann.de/
GnuPG Key: 0xB85B5D69 / 27A7 2B14 09E4 98CD 6277 0E5B 6867 C514 B85B 5D69