On Fri, Oct 10, 2008 at 3:32 PM, Nathan Rixham <nrixham@xxxxxxxxx> wrote:
> Alan Boudreault wrote:
>>
>> Hi all,
>>
>> I'm wondering why PHP doesn't free my memory with this test code. The
>> memory usage is always the same even if i unset my object. The Garbage
>> collector seems to only free the memory at the end of the script.
>>
>> Here's the php Scripts that i use for testing:
>>
>> <?php
>> //dl("php_mapscript.so");
>>
>> function test() {
>> $oShapeFile = ms_newShapefileObj(
>> "/opt/www/bdga/msp/data/bdga/BDGA_HYDRO_S_POLY.shp", -1);
>> echo "before getShape : ".memory_get_usage(true)."\n";
>> for ($i=0; $i<$oShapeFile->numshapes;$i++) {
>> $oShape = $oShapeFile->getShape($i);
>> $oShape->free();
>> unset($oShape);
>> $oShape = NULL;
>> }
>>
>> echo "after getShape : ".memory_get_usage(true)."\n";
>> $oShapeFile->free();
>> unset($oShapeFile);
>> $oShapeFile = null;
>>
>> echo "after free : ".memory_get_usage(true)."\n";
>> }
>>
>> echo "start : ".memory_get_usage(true)."\n";
>> test();
>> echo "end : ".memory_get_usage(true)."\n";
>>
>> ?>
>>
>> Output result:
>> start : 262144
>> before getShape : 262144
>> after getShape : 11010048
>> after free : 11010048
>> end : 11010048
>>
>> I've also run valgrind to be sure that is not my extension that doesn't
>> free its memory:
>> $ valgrind --leak-check=full php -f shapeTest.php
>> ==18730== LEAK SUMMARY:
>> ==18730== definitely lost: 0 bytes in 0 blocks.
>> ==18730== possibly lost: 0 bytes in 0 blocks.
>> ==18730== still reachable: 240 bytes in 2 blocks.
>> ==18730== suppressed: 0 bytes in 0 blocks.
>>
>>
>> Thanks,
>> Alan
>>
>
> interesting, I'm finding the same thing in one of my atom feed parsers; over
> time no matter how much I unset / truncate variables the memory usage stills
> grows over time - at this time I can't find any way to bring it right down;
> on a timer the whole script resets and restarts itself;
>
> one thing I have noticed is that I can see the emalloc memory usage report
> dropping and rising [memory_get_usage( false );], but still rising over
> time..
>
> hope this wasn't a hijack; just here trying to figure out the same problem
> at the minute!
>
> Regards..
>
> Nathan
>
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>
I think the engine doesn't really worry about freeing memory until it
has to. Or was this only on circular references? I remember there
was that whole GSOC project to implement garbage collection, but it
never got implemented. Maybe someone who really knows will chime in.
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