[Valgrind-users] Conflicting load reported on libstdc++ std::string

[Bart V. A. <bva...@ac...>]

On Tue, May 11, 2010 at 11:20 AM, Konstantin Serebryany <
kon...@gm...> wrote:

>
>> Have you already found a workaround that allows to avoid triggering
>> the race report on std::locale::locale() ? If not, it would help if
>> you could post a small example that allows to reproduce this behavior.
>>
>
> You may like the test NegativeTests.EmptyRepTest from
> http://code.google.com/p/data-race-test/wiki/RacecheckUnittest
>
> % ~/valgrind/trunk/inst/bin/valgrind --tool=helgrind
> ./bin/racecheck_unittest-linux-x86-O0
> --gtest_filter="NegativeTests.EmptyRepTest"
>
> ==28925== Possible data race during read of size 4 at 0x7fbf5b8 by thread
> #3
> ==28925==    at 0x7F6F3A2: std::string::erase(unsigned int, unsigned int)
> (in /usr/grte/v1/lib/libstdc++.so.6.0.9)
> ==28925==    by 0x804CB82: NegativeTests_EmptyRep::Worker()
> (racecheck_unittest.cc:3168)
> ==28925==    by 0x806E806: MyThread::ThreadBody(MyThread*)
> (thread_wrappers_pthread.h:329)
> ==28925==    by 0x47C4155: mythread_wrapper (hg_intercepts.c:213)
> ==28925==    by 0x47F1024: start_thread (in /usr/grte/v1/lib/
> libpthread-2.3.6.so)
> ==28925==    by 0x1BD4A75D: clone (in /usr/grte/v1/lib/libc-2.3.6.so)
> ==28925==  This conflicts with a previous write of size 4 by thread #2
> ==28925==    at 0x7F6EC1B: std::string::_M_mutate(unsigned int, unsigned
> int, unsigned int) (in /usr/grte/v1/lib/libstdc++.so.6.0.9)
> ==28925==    by 0x7F6F3C6: std::string::erase(unsigned int, unsigned int)
> (in /usr/grte/v1/lib/libstdc++.so.6.0.9)
> ==28925==    by 0x804CB82: NegativeTests_EmptyRep::Worker()
> (racecheck_unittest.cc:3168)
> ==28925==    by 0x806E806: MyThread::ThreadBody(MyThread*)
> (thread_wrappers_pthread.h:329)
> ==28925==    by 0x47C4155: mythread_wrapper (hg_intercepts.c:213)
> ==28925==    by 0x47F1024: start_thread (in /usr/grte/v1/lib/
> libpthread-2.3.6.so)
> ==28925==    by 0x1BD4A75D: clone (in /usr/grte/v1/lib/libc-2.3.6.so)
>
>
> % ~/valgrind/trunk/inst/bin/valgrind --tool=drd
> ./bin/racecheck_unittest-linux-x86-O0
> --gtest_filter="NegativeTests.EmptyRepTest"
>
> ==28930==
> ==28930== Conflicting load by thread 3 at 0x04b1f5b8 size 4
> ==28930==    at 0x4ACEB7E: std::string::_M_mutate(unsigned int, unsigned
> int, unsigned int) (in /usr/grte/v1/lib/libstdc++.so.6.0.9)
> ==28930==    by 0x4ACF3C6: std::string::erase(unsigned int, unsigned int)
> (in /usr/grte/v1/lib/libstdc++.so.6.0.9)
> ==28930==    by 0x804CB82: NegativeTests_EmptyRep::Worker()
> (racecheck_unittest.cc:3168)
> ==28930==    by 0x806E806: MyThread::ThreadBody(MyThread*)
> (thread_wrappers_pthread.h:329)
> ==28930==    by 0x47C9BBD: vgDrd_thread_wrapper
> (drd_pthread_intercepts.c:272)
> ==28930==    by 0x47F7024: start_thread (in /usr/grte/v1/lib/
> libpthread-2.3.6.so)
> ==28930==    by 0x4BED75D: clone (in /usr/grte/v1/lib/libc-2.3.6.so)
> ==28930== Allocation context: BSS section of
> /usr/grte/v1/lib/libstdc++.so.6.0.9
> ==28930== Other segment start (thread 2)
> ==28930==    (thread finished, call stack no longer available)
> ==28930== Other segment end (thread 2)
> ==28930==    (thread finished, call stack no longer available)
> ==28930==
>

Why did you post this in reply to a message about std::locale::locale() ? As
far as I can see the race reported on the std::string object and the race
reported on std::locale::locale() are unrelated.

Bart.