<div dir="ltr"><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Mar 19, 2014 at 6:42 PM, Bryan Keiren <span dir="ltr"><<a href="mailto:bryan.keiren@guerrilla-games.com" target="_blank">bryan.keiren@guerrilla-games.com</a>></span> wrote:<br>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I’m not involved with however our threading is implemented or used ;) All I know is that we’re trying to match each allocation with a de-allocation and the
way the LLVM code currently works is not compatible with this philosophy. Because we felt this might have been an issue with LLVM itself we decided to go here and ask you guys.<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">We will probably just patch LLVM locally (argh, I can already hear the muttered curses of the people who have to re-patch a future version upgrade… Haha).</span></p>
</div></div></blockquote><div><br></div><div>As Kostya mentioned, requiring that each allocated chunk of memory should be deallocated before exiting main() is rather impractical for C++, as this wouldn't work in multithreaded environment where the memory should be accessible by threads even after main() exits, and threads can't be joined because there can be no valid shutdown order. Even if you can guarantee this doesn't happen in your setting, it isn't so for all users of LLVM libraries.</div>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Kostya Serebryany [mailto:<a href="mailto:kcc@google.com" target="_blank">kcc@google.com</a>]
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<b>Sent:</b> Wednesday, March 19, 2014 15:29<br>
<b>To:</b> Bryan Keiren<br>
<b>Cc:</b> Caldarale, Charles R; <a href="mailto:llvmdev@cs.uiuc.edu" target="_blank">llvmdev@cs.uiuc.edu</a><br>
<b>Subject:</b> Re: [LLVMdev] getElapsedWallTime unnecessary heap allocation and memory leak<u></u><u></u></span></p><div><div class="h5">
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<p class="MsoNormal">On Wed, Mar 19, 2014 at 6:18 PM, Bryan Keiren <<a href="mailto:bryan.keiren@guerrilla-games.com" target="_blank">bryan.keiren@guerrilla-games.com</a>> wrote:<u></u><u></u></p>
<p class="MsoNormal">We are indeed trying to completely clean the heap before exiting main().<u></u><u></u></p>
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<p class="MsoNormal">Which means that you either don't have threads, or you join all threads before main exits.<u></u><u></u></p>
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<p class="MsoNormal">Is that the case?<u></u><u></u></p>
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<p class="MsoNormal">Good for you if so! <u></u><u></u></p>
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-----Original Message-----<br>
From: Caldarale, Charles R [mailto:<a href="mailto:Chuck.Caldarale@unisys.com" target="_blank">Chuck.Caldarale@unisys.com</a>]<br>
Sent: Wednesday, March 19, 2014 14:42<br>
To: Bryan Keiren; <a href="mailto:llvmdev@cs.uiuc.edu" target="_blank">llvmdev@cs.uiuc.edu</a><br>
Subject: RE: [LLVMdev] getElapsedWallTime unnecessary heap allocation and memory leak<br>
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> From: <a href="mailto:llvmdev-bounces@cs.uiuc.edu" target="_blank">llvmdev-bounces@cs.uiuc.edu</a> [mailto:<a href="mailto:llvmdev-bounces@cs.uiuc.edu" target="_blank">llvmdev-bounces@cs.uiuc.edu</a>]<br>
> On Behalf Of Bryan Keiren<br>
> Subject: [LLVMdev] getElapsedWallTime unnecessary heap allocation and<br>
> memory leak<br>
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> In the file \lib\Support\Process.cpp on line 60, it seems as though an<br>
> unnecessary heap allocation and memory leak occurs.<br>
<br>
> static TimeValue getElapsedWallTime() {<br>
> static TimeValue &StartTime = *new TimeValue(TimeValue::now());<br>
> return TimeValue::now() - StartTime;<br>
> }<br>
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> The issue is that the StartTime variable's value is allocated on the<br>
> heap, after which a *reference* to it is stored (not the pointer<br>
> itself). This means that the allocated memory is actually never properly de-allocated.<br>
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Since the StartTime field is static, why is this considered a leak? The reference has not been lost and is utilized whenever getElapsedWallTime() is invoked. Although it might be infinitesimally more efficient to avoid the new operator, the overall memory
consumption is almost identical.<br>
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Are you trying to get rid of the entire heap at some point before process termination?<br>
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- Chuck<br>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div>Alexey Samsonov, MSK</div>
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