Dear all,
When I compile the following program with:
$ g++ -g -pthread threads.cpp
// begin program /////////////////////////////////////////////
// file: threads.cpp
#include <pthread.h>
#include <iostream>
#include <sstream>
void *threadEntry(void *threadid)
{
long tid;
tid = (long)threadid;
for (int i = 0; i<5; i++) {
std::stringstream myStream;
myStream << "this thread is " << tid;
std::string myString(myStream.str());
pthread_yield();
}
pthread_exit(NULL);
}
int main (int argc, char *argv[])
{
pthread_t threads[2];
int rc;
long t;
for(t=0; t<2; t++) {
rc = pthread_create(&threads[t], NULL, threadEntry, (void *)t);
}
pthread_exit(NULL);
}
// end program /////////////////////////////////////////////
and run drd on it with:
$ valgrind --tool=drd ./a.out
I get the following output:
==16240== drd, a thread error detector
==16240== Copyright (C) 2006-2009, and GNU GPL'd, by Bart Van Assche.
==16240== Using Valgrind-3.5.0-Debian and LibVEX; rerun with -h for
copyright info
==16240== Command: ./a.out
==16240==
==16240== Thread 3:
==16240== Conflicting load by thread 3 at 0x05132e98 size 1
==16240== at 0x4ED44C8: std::ostream&
std::ostream::_M_insert<long>(long) (in /usr/lib/libstdc++.so.6.0.13)
==16240== by 0x400C48: threadEntry(void*) (threads.cpp:12)
==16240== by 0x4C32870: vgDrd_thread_wrapper (drd_pthread_intercepts.c:272)
==16240== by 0x55E8A03: start_thread (pthread_create.c:300)
==16240== by 0x58DD80C: clone (clone.S:112)
==16240== Allocation context: BSS section of /usr/lib/libstdc++.so.6.0.13
==16240== Other segment start (thread 2)
==16240== at 0x4C29F2F: pthread_mutex_unlock (drd_pthread_intercepts.c:633)
==16240== by 0x4EA387E: std::locale::locale() (in
/usr/lib/libstdc++.so.6.0.13)
==16240== by 0x4E9FE5F: std::ios_base::_M_init() (in
/usr/lib/libstdc++.so.6.0.13)
==16240== by 0x4EB4768: std::basic_ios<char, std::char_traits<char>
>::init(std::basic_streambuf<char, std::char_traits<char> >*) (in
/usr/lib/libstdc++.so.6.0.13)
==16240== by 0x4ED7DEA: std::basic_stringstream<char,
std::char_traits<char>, std::allocator<char>
>::basic_stringstream(std::_Ios_Openmode) (in
/usr/lib/libstdc++.so.6.0.13)
==16240== by 0x400C21: threadEntry(void*) (threads.cpp:11)
==16240== by 0x4C32870: vgDrd_thread_wrapper (drd_pthread_intercepts.c:272)
==16240== by 0x55E8A03: start_thread (pthread_create.c:300)
==16240== by 0x58DD80C: clone (clone.S:112)
==16240== Other segment end (thread 2)
==16240== at 0x58ACEB7: sched_yield (in /lib/libc-2.10.1.so)
==16240== by 0x400C63: threadEntry(void*) (threads.cpp:14)
==16240== by 0x4C32870: vgDrd_thread_wrapper (drd_pthread_intercepts.c:272)
==16240== by 0x55E8A03: start_thread (pthread_create.c:300)
==16240== by 0x58DD80C: clone (clone.S:112)
==16240==
==16240== Conflicting load by thread 3 at 0x05132eb9 size 1
==16240== at 0x4ED44D3: std::ostream&
std::ostream::_M_insert<long>(long) (in /usr/lib/libstdc++.so.6.0.13)
==16240== by 0x400C48: threadEntry(void*) (threads.cpp:12)
==16240== by 0x4C32870: vgDrd_thread_wrapper (drd_pthread_intercepts.c:272)
==16240== by 0x55E8A03: start_thread (pthread_create.c:300)
==16240== by 0x58DD80C: clone (clone.S:112)
==16240== Allocation context: BSS section of /usr/lib/libstdc++.so.6.0.13
==16240== Other segment start (thread 2)
==16240== at 0x4C29F2F: pthread_mutex_unlock (drd_pthread_intercepts.c:633)
==16240== by 0x4EA387E: std::locale::locale() (in
/usr/lib/libstdc++.so.6.0.13)
==16240== by 0x4E9FE5F: std::ios_base::_M_init() (in
/usr/lib/libstdc++.so.6.0.13)
==16240== by 0x4EB4768: std::basic_ios<char, std::char_traits<char>
>::init(std::basic_streambuf<char, std::char_traits<char> >*) (in
/usr/lib/libstdc++.so.6.0.13)
==16240== by 0x4ED7DEA: std::basic_stringstream<char,
std::char_traits<char>, std::allocator<char>
>::basic_stringstream(std::_Ios_Openmode) (in
/usr/lib/libstdc++.so.6.0.13)
==16240== by 0x400C21: threadEntry(void*) (threads.cpp:11)
==16240== by 0x4C32870: vgDrd_thread_wrapper (drd_pthread_intercepts.c:272)
==16240== by 0x55E8A03: start_thread (pthread_create.c:300)
==16240== by 0x58DD80C: clone (clone.S:112)
==16240== Other segment end (thread 2)
==16240== at 0x58ACEB7: sched_yield (in /lib/libc-2.10.1.so)
==16240== by 0x400C63: threadEntry(void*) (threads.cpp:14)
==16240== by 0x4C32870: vgDrd_thread_wrapper (drd_pthread_intercepts.c:272)
==16240== by 0x55E8A03: start_thread (pthread_create.c:300)
==16240== by 0x58DD80C: clone (clone.S:112)
==16240==
==16240==
==16240== For counts of detected and suppressed errors, rerun with: -v
==16240== ERROR SUMMARY: 6 errors from 2 contexts (suppressed: 208 from 140)
My question is: Are the errors reported real multi threading errors?
If not, how can I tell drd to suppress them? (In my real world program, I
have thousands of errors in hundreds of contexts, and I am trying to
find the real ones.)
If yes, can you help me understand what is wrong? Both threads only
use local variables. I have been reading about the global object
"locale" used by streams for localization, but I have read that it is
protected by a global mutex.
By the way, if in the program above I don't include iostream, then drd
reports almost a thousand errors from a hundred contexts!
Thank you very much!
Jorge Moraleda
FYI: I am running ubuntu linux 9.10. This is my system:
$ valgrind --version
valgrind-3.5.0-Debian
$ uname -r
2.6.31-20-generic
$ gcc -v
Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
4.4.1-4ubuntu9'
--with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr
--enable-shared --enable-multiarch --enable-linker-build-id
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4
--program-suffix=-4.4 --enable-nls --enable-clocale=gnu
--enable-libstdcxx-debug --enable-objc-gc --disable-werror
--with-arch-32=i486 --with-tune=generic --enable-checking=release
--build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 4.4.1 (Ubuntu 4.4.1-4ubuntu9)
------------------------------------------------------------------------------
Download Intel® Parallel Studio Eval
Try the new software tools for yourself. Speed compiling, find bugs
proactively, and fine-tune applications for parallel performance.
See why Intel Parallel Studio got high marks during beta.
http://p.sf.net/sfu/intel-sw-dev
_______________________________________________
Valgrind-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/valgrind-users
