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https://issues.apache.org/jira/browse/XERCESC-2162?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16719457#comment-16719457
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Roger Leigh commented on XERCESC-2162:
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I'm unsure why volatile would be a needed qualifier on these specific
variables. They shouldn't be optimised out, irrespective of whether volatile
is added or not.
fHeartBeat is intrinsically racy from what I can see; it's modified by both the
main thread and the corresponding worker, and read in the main thread, but it's
only used for some cosmetic reporting symbols as far as I can see. Moreover,
we always run the thread tests with -quiet, so "if (gRunInfo.quiet == false..."
on 1306 should always be false. fHeartBeat should be written once by the
worker for each pass and never read.
fInProgress is written in the worker and checked in the main thread at
termination; should be safe given how it's used with or without volatile. I
can see this deadlocking if a worker terminates early; it will never be reset
back to false.
fParses isn't actually used except for some trivial reporting; shouldn't be
optimised out though
fThreadNum is set once in the main thread and read by the worker, should be safe
Are all four of these structure members definitely optimised out? Can you put
a breakpoint in one of the workers and check each member at e.g. thInfo at line
1077 and 1150 for a few passes.
I'm suspicious that the volatile qualifiers are hiding some deeper problem. It
shouldn't be required for multi-threaded code, and neither GCC, Clang nor MSVC
are optimising anything away. The compiler doesn't have sufficient information
to elide these members as far as I can see. They are being passed by pointer
to the thread main for each worker, and that should surely be a barrier to
optimisation; the compiler should not be able to determine that it's not
modified at this point, and that should kill any elision. At least, that's my
take on it, but I could certainly be wrong.
The 21 second timeout is because the test is run with "-time 20" and there's a
final 1 second delay while the threads terminate. This is adjustable in the
test configuration.
> ThreadTest freezes with Intel 17.0.5.239 and 18.0.1.163
> -------------------------------------------------------
>
> Key: XERCESC-2162
> URL: https://issues.apache.org/jira/browse/XERCESC-2162
> Project: Xerces-C++
> Issue Type: Bug
> Components: Samples/Tests
> Affects Versions: 3.2.2
> Environment: cat /etc/redhat-release
> Red Hat Enterprise Linux Server release 7.6 (Maipo)
> uname -a
> Linux tfe10 3.10.0-957.el7.x86_64 #1 SMP Thu Oct 4 20:48:51 UTC 2018 x86_64
> x86_64 x86_64 GNU/Linux
> Two versions of the Intel compiler suite were tried:
> icpc --version
> icpc (ICC) 17.0.5 20170817
> Copyright (C) 1985-2017 Intel Corporation. All rights reserved.
> icc --version
> icc (ICC) 17.0.5 20170817
> Copyright (C) 1985-2017 Intel Corporation. All rights reserved.
> icpc --version
> icpc (ICC) 18.0.1 20171018
> Copyright (C) 1985-2017 Intel Corporation. All rights reserved.
> icc --version
> icc (ICC) 18.0.1 20171018
> Copyright (C) 1985-2017 Intel Corporation. All rights reserved.
> Reporter: Sam Trahan
> Priority: Major
>
> The ThreadTest1 hangs forever when Xerces-C 3.2.2 is compiled using the Intel
> compiler versions 17.0.5.239 or 18.0.1.163. Running ThreadTest1 directly in
> gdb reveals that all ten threads exit, and main() is stuck in a wait loop
> calling sleep() forever.
> export CXX=icpc
> export CFLAGS='-fp-model precise'
> export CXXFLAGS='-fp-model precise'
> export CC=icc
> export CPP="icc -E"
> export CXXCPP="icpc -E"
> ./configure --prefix=/some/path
> make
> make check
> Changing the CXXFLAGS to this does not help:
> export CXXFLAGS='-fp-model precise -std=c++11'
> The last bit of output from "make check:"
> make[3]: Entering directory `/a-very-long-path/.../tests'
> PASS: scripts/DOMTest
> PASS: scripts/DOMMemTest
> PASS: scripts/RangeTest
> PASS: scripts/DOMTraversalTest
> XFAIL: scripts/XSerializerTest
> PASS: scripts/XSerializerTest1
> PASS: scripts/XSerializerTest2
> PASS: scripts/XSerializerTest3
> PASS: scripts/XSerializerTest4
> PASS: scripts/XSerializerTest5
> PASS: scripts/XSValueTest
> XFAIL: scripts/InitTermTest
> PASS: scripts/InitTermTest1
> PASS: scripts/InitTermTest2
> PASS: scripts/InitTermTest3
> XFAIL: scripts/ThreadTest
> The test hangs at that XFAIL: line. The "ps" command reveals ThreadTest1 is
> running:
> /a-very-long-path/.../tests/.libs/lt-ThreadTest -parser=sax -v=never -quiet
> -threads 10 -time 20 personal.xml
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