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Date: Fri, 23 Jan 2004 03:58:00 -0000
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From: "ljrittle at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
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Reply-To: gcc-bugzilla@gcc.gnu.org
Subject: [Bug libstdc++/13823] Significant performance issue with std::map on multiple threads on dual processor - possibly default allocator
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X-SW-Source: 2004-01/txt/msg02885.txt.bz2
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------- Additional Comments From ljrittle at gcc dot gnu dot org  2004-01-23 03:58 -------
Try this (we might change the default allocator to make it work better for MP
at the next major library revision --- ABI change, but 3.4 will support this
allocator
with very good performance for people that wish to tune their application):

#include <iostream>
#include <map>
#include <ext/mt_allocator.h>

void *calc(void *n)
{
  std::map<int, int, std::less<const int>,
           __gnu_cxx::__mt_alloc< std::pair<const int, int> > > m;
      
  for (unsigned i = 0; i < 100000; ++i) 
    m[i] = i;

  return 0;
}

int main(int argc, char *argv[])
{
  int n = argc == 2 ? std::max(atoi(argv[1]), 1) : 2;

  pthread_t id[n];

  for (int i = 0; i < n; ++i)
    pthread_create(&id[i], 0, calc, new int(i));
  
  for (int i = 0; i < n; ++i)
    pthread_join(id[i], 0);
  
  return 0;
}

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |SUSPENDED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13823