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POMemory leak when using OpenMP
 

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    <p>The below test case runs out of memory on 32 bit machines (throwing std::bad_alloc) in the loop following the "post MT section" message when OpenMP is used, however, if the #pragmas for OpenMP are commented out, the code runs through to completion fine, so it appears that when the memory is allocated in parallel threads, it does not free correctly and thus we run out of memory.</p> <p>Question is whether there is something wrong with the memory allocation and deletion code below or is this a bug in gcc v4.2.2 or OpenMP? I also tried gcc v4.3 and got same failure.</p> <pre><code>int main(int argc, char** argv) { std::cout &lt;&lt; "start " &lt;&lt; std::endl; { std::vector&lt;std::vector&lt;int*&gt; &gt; nts(100); #pragma omp parallel { #pragma omp for for(int begin = 0; begin &lt; int(nts.size()); ++begin) { for(int i = 0; i &lt; 1000000; ++i) { nts[begin].push_back(new int(5)); } } } std::cout &lt;&lt; " pre delete " &lt;&lt; std::endl; for(int begin = 0; begin &lt; int(nts.size()); ++begin) { for(int j = 0; j &lt; nts[begin].size(); ++j) { delete nts[begin][j]; } } } std::cout &lt;&lt; "post MT section" &lt;&lt; std::endl; { std::vector&lt;std::vector&lt;int*&gt; &gt; nts(100); int begin, i; try { for(begin = 0; begin &lt; int(nts.size()); ++begin) { for(i = 0; i &lt; 2000000; ++i) { nts[begin].push_back(new int(5)); } } } catch (std::bad_alloc &amp;e) { std::cout &lt;&lt; e.what() &lt;&lt; std::endl; std::cout &lt;&lt; "begin: " &lt;&lt; begin &lt;&lt; " i: " &lt;&lt; i &lt;&lt; std::endl; throw; } std::cout &lt;&lt; "pre delete 1" &lt;&lt; std::endl; for(int begin = 0; begin &lt; int(nts.size()); ++begin) { for(int j = 0; j &lt; nts[begin].size(); ++j) { delete nts[begin][j]; } } } std::cout &lt;&lt; "end of prog" &lt;&lt; std::endl; char c; std::cin &gt;&gt; c; return 0; } </code></pre>
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    1. COWhen I run this under Windows built with the Intel compiler my allocations start failing in the first loop due to hitting the 2gb limit for a 32 bit process. Is it possible that the overhead of OpenMP is just pushing your process over whatever the limit is on your platform?
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    2. CO@Scott Danahy Try changing the test case to cut all allocations in half, this test worked with a 4 GB limit.
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