<html>
    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - compiler-rt/test/profile/Posix/instrprof-gcov-parallel.test is flaky"
   href="https://bugs.llvm.org/show_bug.cgi?id=45673">45673</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>compiler-rt/test/profile/Posix/instrprof-gcov-parallel.test is flaky
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>compiler-rt
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>10.0
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Linux
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>profile
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>slyfox@inbox.ru
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org, t-kawashima@fujitsu.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Initially noticed as
<a href="http://lab.llvm.org:8011/builders/sanitizer-ppc64be-linux/builds/16358">http://lab.llvm.org:8011/builders/sanitizer-ppc64be-linux/builds/16358</a> where
parallel prof tests found only 6 of 7 samples.

Running locally I seem to observe similar effect:

"""
#!/bin/bash

rm -f instrprof-gcov-parallel.target.gcda instrprof-gcov-parallel.target.c.gcov
instrprof-gcov-parallel.target.gcda instrprof-gcov-parallel.target.gcno

/usr/lib/llvm/10/bin/clang            -o driver
instrprof-gcov-parallel.driver.c
/usr/lib/llvm/10/bin/clang --coverage -o target
instrprof-gcov-parallel.target.c

./driver ./target

llvm-cov gcov instrprof-gcov-parallel.target.gcda >/dev/null 2>&1
fgrep aaa++ instrprof-gcov-parallel.target.c.gcov
"""

"""
$ while :; do ./instrprof-gcov-parallel.test; done
      707:    7:    aaa++;
...
      101:    7:    aaa++;
...
      707:    7:    aaa++;
      707:    7:    aaa++;
...
      606:    7:    aaa++;
      707:    7:    aaa++;
      404:    7:    aaa++;
      707:    7:    aaa++;
"""

"""
$ clang --version
clang version 10.0.0
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/lib/llvm/10/bin
"""

Could be some race in handling SIGCHLD and normal process execution?</pre>
        </div>
      </p>


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