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<base href="http://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Infrequent deadlocks with std::future"
href="http://llvm.org/bugs/show_bug.cgi?id=21995">21995</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Infrequent deadlocks with std::future
</td>
</tr>
<tr>
<th>Product</th>
<td>libc++
</td>
</tr>
<tr>
<th>Version</th>
<td>3.4
</td>
</tr>
<tr>
<th>Hardware</th>
<td>All
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>All Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>brian@fiftythree.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu, mclow.lists@gmail.com
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=13582" name="attach_13582" title="Simple app to stress-test std::future">attachment 13582</a> <a href="attachment.cgi?id=13582&action=edit" title="Simple app to stress-test std::future">[details]</a></span>
Simple app to stress-test std::future
We see occasional deadlocks with std::future, first observed on iOS. We then
wrote a test program (attached) to try and isolate the problem. The test
program simulates a work queue and repeatedly creates stack-allocated futures
to track background "tasks".
The program deadlocks when built for OS X in both Xcode 5.1 & 6.1.1.
It also fails when compiled on Ubuntu Trusty with clang 3.4 and clang 3.6, but
segfaults rather than deadlocking.
Test program compiled as:
clang++-3.6 -o future-shock -std=c++11 -pthread -g future_shock.cpp
vagrant@vagrant-ubuntu-trusty-64:~$ clang++-3.6 -v
Ubuntu clang version 3.6.0-svn224581-1~exp1 (trunk) (based on LLVM 3.6.0)
Target: x86_64-pc-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.8.2
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.9.1
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.2
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.1
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.8
Candidate multilib: .;@m64
Selected multilib: .;@m64</pre>
</div>
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