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From Tom Schindl <tomAtLi...@gmx.at>
Subject Re: No image creation in mod_perl
Date Tue, 28 Mar 2006 10:48:59 GMT
Well this example does not demonstrate the problem it demonstrates the
solution to let perl free memory allocated once by setting the variable
to undef ;-)

---------------8<---------------
#!/usr/bin/perl


&bla();
print "Done";
my $bla = <STDIN>;

sub bla {
   my $var = "";
   for( 1 .. 10_000_000  ) {
      $var .= "xxx";
   }

#   undef $var; # The solution to wipe out allocated memory
                # by explicitly setting vars to undef
}
---------------8<---------------


Tom

Tom Schindl wrote:
> You can try memory management yourself and see that the memory allocated
> is not wiped until the script is finished.
> 
> --------------------8<--------------------
> #!/usr/bin/perl
> 
> &bla();
> print "Done";
> 
> sub bla {
>    my $var = "";
>    for( 1 .. 10_000_000  ) {
>       $var .= "xxx";
>    }
> 
>    my $bla = <STDIN>;
>    undef $var;
> }
> --------------------8<--------------------
> 
> You can modify this example to use threads and see what's happeing to
> your memory.
> 
> Tom
> 
> 
> Foo Ji-Haw wrote:
> 
>>Hello Carl,
>>
>>
>>>Nope that's right, so you load up one image. The perl process
>>>allocates itself 100MB of memory for it from the OS. Then doesn't
>>>release it back to the OS once it's finished with.
>>>
>>>The perl process will re-use this memory, so if you process another
>>>image you don't grab another 100MB, it's just not available at the OS
>>>level or for other processes.
>>>
>>>This isn't completely bad as long as your OS has good memory
>>>management. The unused memory in the perl process will just be swapped
>>>out to disk and left there until that process uses it again or exits.
>>
>>Can I confirm that in the Windows implementation, if a thread allocates
>>requires 100MB of memory and then releases it, the next thread can reuse
>>that memory?
>>
>>Thanks.
>>
>>
> 
> 


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