Re: [Boost-users] Changing the heap allocator

From: Victor A. Wagner Jr. (vawjr_at_[hidden])
Date: 2004-04-10 03:16:30

re: (because of msvcp60.dll)
that may sum up the entire problem.... VC++6.0 is broken...period...simple 
statement of fact
it was replaced 2 years ago by .net then again by .net2003
you may wish to test with a current version

At Wednesday 2004-04-07 19:54, you wrote:
>Hi,
>
>I'm working on a project where I've replaced Microsoft's (terrible) heap 
>allocator with the Doug Lea allocator.  There seems to be some cases where 
>the Windows XP allocator is 500 times slower than it should be.  This made 
>my program take minutes rather than seconds to run.  To try to understand 
>what kind of allocation patterns cause the behaviour I wrote a small 
>console application (see below).  After playing around with different 
>allocation patterns for half an hour I found a case where the pathological 
>behaviour appeared.  I'm none the wiser about the problem.  For example, 
>moving the malloc(301) statement before the 7 x malloc(1000) makes the 
>problem go away!   However, given the ease with which I rediscovered the 
>problem, I wonder why there aren't more complaints about Microsoft's heap 
>allocator.  With some allocation patterns I have seen the allocator fall 
>below 1kHz on a Pentium IV 2GHz machine!
>
>I've created a library that exports alternative versions of operator new 
>and operator delete, by using a def file as follows
>
>EXPORTS
>       ??2_at_YAPAXI@Z
>       ??3_at_YAXPAX@Z
>
>I've had to do some hacky things to make it work with the STL (because of 
>msvcp60.dll) , but that's another story!
>
>Now my question : I want to use boost, but need to work out how to make it 
>use a different allocator.  Will I need to rebuild the boost dlls (such as 
>boost_python.dll),  against my static library?
>
>
>Regards,
>David Barrett-Lennard
>
>
>/////////////////////// heap allocation test ///////////////////////////
>
>#include <iostream>
>#include <time.h>
>
>int main(int argc, char* argv[])
>{
>     for (int count=1 ; count <= 5 ; ++count)
>     {
>         int n1 = 0, n2 = 0;
>         clock_t start = clock();
>         {
>             const int NUM = 10000;
>             void* L[NUM*7];
>             for (int i=0 ; i < NUM ; ++i)
>             {
>                 for (int j=0 ; j < 7 ; ++j) L[n1++] = malloc(1000);
>                 void* leak = malloc(301);
>                 ++n2;
>             }
>             for (int k=n1-1 ; k >= 0 ; --k) free(L[k]);
>         }
>         clock_t elapsed = clock()-start;
>         if (elapsed)
>         {
>             std::cout << "Time = " << elapsed << " ms"
>                       << "  Rate = " << 1000 * (n1 + n2) / elapsed << " Hz"
>                       << std::endl;
>         }
>     }
>     return 0;
>}
>
>
>
>
>
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Victor A. Wagner Jr.      http://rudbek.com
The five most dangerous words in the English language:
               "There oughta be a law"