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https://issues.apache.org/jira/browse/XERCESC-2162?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16719074#comment-16719074
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Sam Trahan edited comment on XERCESC-2162 at 12/12/18 5:29 PM:
---------------------------------------------------------------

I tried three tests and determined the problem was a few missing "volatile" 
declarations.  The test takes 21.05 seconds to pass, which suggests to me that 
there is another problem somewhere.

Test 1: no optimization - works
Test 2: full debugging plus -O3 - fails just the same
Test 3: add "volatile" declarations in four places, full debugging, plus -O3 - 
works, but takes 21.05 seconds

(gdb) where
#0  0x00007ffe8e57fe2d in nanosleep () from /lib64/libc.so.6
#1  0x00007ffe8e57fcc4 in sleep () from /lib64/libc.so.6
#2  0x0000000000409912 in main (argc=-21216, argv=0x7fffffffad20)
    at /a-very-long-path/.../ThreadTest.cpp:1334

The failure is here:

                for (threadNum=0; threadNum < gRunInfo.numThreads; threadNum++) 
{
                    if (gThreadInfo[threadNum].fHeartBeat == false) {

The fHeartBeat is optimized away because it was not declared volatile:

(gdb) print gThreadInfo[threadNum].fInProgress
value has been optimized out

There is no "volatile" protecting the variable, nor any data structure 
containing it.  Thus, the compiler is free to optimize it any way it wants to.  
If I add "volatile" to these declarations, the thread tests pass, but take 
21.05 seconds each to do it, which suggests there is another problem somewhere.

    volatile bool            fHeartBeat;   // Set true by the thread each time 
it finishes                                                                     
                
                                  //   parsing a file.                          
                                                                                
               
    volatile bool            fInProgress;  // Set to false by the thread when 
parse in progress                                                               
                 
    volatile unsigned int    fParses;      // Number of parses completed.       
                                                                                
               
    volatile int             fThreadNum;   // Identifying number for this 
thread.                                                                         
                     




was (Author: samueltrahannoaa):
I tried two tests and determined the problem was a few missing "volatile" 
declarations.  The test takes 21.05 seconds to pass, which suggests to me that 
there is another problem somewhere.

Test 1: no optimization - works
Test 2: full debugging plus -O3 - fails just the same

(gdb) where
#0  0x00007ffe8e57fe2d in nanosleep () from /lib64/libc.so.6
#1  0x00007ffe8e57fcc4 in sleep () from /lib64/libc.so.6
#2  0x0000000000409912 in main (argc=-21216, argv=0x7fffffffad20)
    at /a-very-long-path/.../ThreadTest.cpp:1334

The failure is here:

                for (threadNum=0; threadNum < gRunInfo.numThreads; threadNum++) 
{
                    if (gThreadInfo[threadNum].fHeartBeat == false) {

The fHeartBeat is optimized away because it was not declared volatile:

(gdb) print gThreadInfo[threadNum].fInProgress
value has been optimized out

There is no "volatile" protecting the variable, nor any data structure 
containing it.  Thus, the compiler is free to optimize it any way it wants to.  
If I add "volatile" to these declarations, the thread tests pass, but take 
21.05 seconds each to do it, which suggests there is another problem somewhere.

    volatile bool            fHeartBeat;   // Set true by the thread each time 
it finishes                                                                     
                
                                  //   parsing a file.                          
                                                                                
               
    volatile bool            fInProgress;  // Set to false by the thread when 
parse in progress                                                               
                 
    volatile unsigned int    fParses;      // Number of parses completed.       
                                                                                
               
    volatile int             fThreadNum;   // Identifying number for this 
thread.                                                                         
                     



> 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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