thread lock-guard race condition
Hello, I have written this little example: boost::mutex mutex; void thread() { for (int i = 0; i < 5; ++i) { boost::this_thread::sleep(boost::posix_time::seconds(3)); boost::lock_guard<boost::mutex> lock(mutex); std::cout << "Thread " << boost::this_thread::get_id() << ": " << i << std::endl; } } int main(int argc, char *argv[]) { boost::thread t1(thread); boost::thread t2(thread); t1.join(); t2.join(); } I compile the code with pthread option on the gcc (4.0.1). In the first case the program works, but if I use the helgrind tool of valgrind I'll get this errors (sorry for the long messages). I would like to understand what I have done wrong. I hope I understand the lock_guard in the correct way: If I create the lock with the mutex variable the thread, that creates the lock runs down the next lines. All other threads that run into the lock_guard line blocks until the lock variable of the first thread call the destructor (which should be on every loop iteration). Thanks for help Phil ------Valgrind Logs----------- ==19846== Thread #1 is the program's root thread ==19846== Thread #3 & #2 was created ==19846== at 0x15A1FDE: __bsdthread_create (in /usr/lib/ libSystem.B.dylib) ==19846== by 0x378F4: pthread_create_WRK (hg_intercepts.c:257) ==19846== by 0x379C8: pthread_create (hg_intercepts.c:294) ==19846== by 0x55C06: boost::thread::start_thread() (in libboost_thread.dylib) ==19846== by 0x9FED: boost::thread::thread<void (*)()>(void (*)(), boost::disable_if<boost::is_convertible<void (*&)(), boost::detail::thread_move_t<void (*)()> >, boost::thread::dummy*>::type) (in ./main) ==19846== by 0x2A82: main (in ./main) This message is show for thread #1, #2 and #3 ==19846== Possible data race during read of size 4 at 0x5e008 by thread #3 ==19846== at 0x56381: void boost::call_once<void (*) ()>(boost::once_flag&, void (*)()) (in libboost_thread.dylib) ==19846== by 0x545AC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/ libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib) ==19846== This conflicts with a previous write of size 4 by thread #2 ==19846== at 0x5647F: void boost::call_once<void (*) ()>(boost::once_flag&, void (*)()) (in /libboost_thread.dylib) ==19846== by 0x545AC: thread_proxy (in /libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/ libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib) ==19846== Thread #2: Bug in libpthread: recursive write lock granted on mutex/wrlock which does not support recursion ==19846== at 0x385D2: pthread_cond_timedwait_WRK (hg_intercepts.c: 764) ==19846== by 0x386B0: pthread_cond_timedwait$* (hg_intercepts.c:798) ==19846== by 0x5AABB: boost ::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost ::this_thread ::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/ libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib) The next message is shown for the thread #2 & #3 ==19846== Thread #3: lock order "0x2500668 before 0x25005C8" violated ==19846== at 0x37E1B: pthread_mutex_lock (hg_intercepts.c:496) ==19846== by 0x5ABA3: boost ::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost ::this_thread ::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/ libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib) ==19846== Required order was established by acquisition of lock at 0x2500668 ==19846== at 0x37E1B: pthread_mutex_lock (hg_intercepts.c:496) ==19846== by 0x15A3452: _pthread_cond_wait (in /usr/lib/ libSystem.B.dylib) ==19846== by 0x15C89F7: pthread_cond_timedwait$UNIX2003 (in /usr/ lib/libSystem.B.dylib) ==19846== by 0x38575: pthread_cond_timedwait_WRK (hg_intercepts.c: 760) ==19846== by 0x386B0: pthread_cond_timedwait$* (hg_intercepts.c:798) ==19846== by 0x5AABB: boost ::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost ::this_thread ::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/ libSystem.B.dylib) ==19846== followed by a later acquisition of lock at 0x25005C8 ==19846== at 0x37E1B: pthread_mutex_lock (hg_intercepts.c:496) ==19846== by 0x53E6A: boost::this_thread::interruption_point() (in libboost_thread.dylib) ==19846== by 0x5AAC2: boost ::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in /libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost ::this_thread ::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/ libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib)
Hi, Phil, Valgrind user manual give no more information than " Applications that use the Boost.Thread library should run fine under DRD." I ran your code using DRD tool of valgrind and got race warnings too. I then ran the following thread_group.cpp code distributed with boost_1_42, debugged it with valgrind --tool=drd, and it gave race warnings (more errors than your code) too: int count = 0; boost::mutex mutex; void increment_count() { boost::mutex::scoped_lock lock(mutex); std::cout << "count = " << ++count << std::endl; } int main(int argc, char* argv[]) { boost::thread_group threads; for (int i = 0; i < 10; ++i) threads.create_thread(&increment_count); threads.join_all(); } This suggests that valgrind might give false race warnings for boost thread code. Although I am not 100% sure of it. BTW, what other debugging tools are available to us for debugging boost threaded code? Robert On Wed, Nov 24, 2010 at 11:05 AM, Kraus Philipp <philipp.kraus@flashpixx.de>wrote:
Hello,
I have written this little example:
boost::mutex mutex;
void thread() { for (int i = 0; i < 5; ++i) { boost::this_thread::sleep(boost::posix_time::seconds(3)); boost::lock_guard<boost::mutex> lock(mutex); std::cout << "Thread " << boost::this_thread::get_id() << ": " << i << std::endl; } }
int main(int argc, char *argv[]) { boost::thread t1(thread); boost::thread t2(thread); t1.join(); t2.join(); }
I compile the code with pthread option on the gcc (4.0.1). In the first case the program works, but if I use the helgrind tool of valgrind I'll get this errors (sorry for the long messages). I would like to understand what I have done wrong. I hope I understand the lock_guard in the correct way: If I create the lock with the mutex variable the thread, that creates the lock runs down the next lines. All other threads that run into the lock_guard line blocks until the lock variable of the first thread call the destructor (which should be on every loop iteration).
Thanks for help
Phil
------Valgrind Logs-----------
==19846== Thread #1 is the program's root thread
==19846== Thread #3 & #2 was created ==19846== at 0x15A1FDE: __bsdthread_create (in /usr/lib/libSystem.B.dylib) ==19846== by 0x378F4: pthread_create_WRK (hg_intercepts.c:257) ==19846== by 0x379C8: pthread_create (hg_intercepts.c:294) ==19846== by 0x55C06: boost::thread::start_thread() (in libboost_thread.dylib) ==19846== by 0x9FED: boost::thread::thread<void (*)()>(void (*)(), boost::disable_if<boost::is_convertible<void (*&)(), boost::detail::thread_move_t<void (*)()> >, boost::thread::dummy*>::type) (in ./main) ==19846== by 0x2A82: main (in ./main)
This message is show for thread #1, #2 and #3
==19846== Possible data race during read of size 4 at 0x5e008 by thread #3 ==19846== at 0x56381: void boost::call_once<void (*)()>(boost::once_flag&, void (*)()) (in libboost_thread.dylib) ==19846== by 0x545AC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib) ==19846== This conflicts with a previous write of size 4 by thread #2 ==19846== at 0x5647F: void boost::call_once<void (*)()>(boost::once_flag&, void (*)()) (in /libboost_thread.dylib) ==19846== by 0x545AC: thread_proxy (in /libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib)
==19846== Thread #2: Bug in libpthread: recursive write lock granted on mutex/wrlock which does not support recursion ==19846== at 0x385D2: pthread_cond_timedwait_WRK (hg_intercepts.c:764) ==19846== by 0x386B0: pthread_cond_timedwait$* (hg_intercepts.c:798) ==19846== by 0x5AABB: boost::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost::this_thread::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib)
The next message is shown for the thread #2 & #3
==19846== Thread #3: lock order "0x2500668 before 0x25005C8" violated ==19846== at 0x37E1B: pthread_mutex_lock (hg_intercepts.c:496) ==19846== by 0x5ABA3: boost::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost::this_thread::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib) ==19846== Required order was established by acquisition of lock at 0x2500668 ==19846== at 0x37E1B: pthread_mutex_lock (hg_intercepts.c:496) ==19846== by 0x15A3452: _pthread_cond_wait (in /usr/lib/libSystem.B.dylib) ==19846== by 0x15C89F7: pthread_cond_timedwait$UNIX2003 (in /usr/lib/libSystem.B.dylib) ==19846== by 0x38575: pthread_cond_timedwait_WRK (hg_intercepts.c:760) ==19846== by 0x386B0: pthread_cond_timedwait$* (hg_intercepts.c:798) ==19846== by 0x5AABB: boost::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost::this_thread::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib) ==19846== followed by a later acquisition of lock at 0x25005C8 ==19846== at 0x37E1B: pthread_mutex_lock (hg_intercepts.c:496) ==19846== by 0x53E6A: boost::this_thread::interruption_point() (in libboost_thread.dylib) ==19846== by 0x5AAC2: boost::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in /libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost::this_thread::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib)
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If I recall, helgrind is not quite as fully-developed as the rest of the valgrind suite, and I do think it can give false positives for race conditions. Brian On Wed, Nov 24, 2010 at 7:48 PM, Boost lzw <boostlzw@gmail.com> wrote:
Hi, Phil,
Valgrind user manual give no more information than " Applications that use the Boost.Thread library should run fine under DRD." I ran your code using DRD tool of valgrind and got race warnings too.
I then ran the following thread_group.cpp code distributed with boost_1_42, debugged it with valgrind --tool=drd, and it gave race warnings (more errors than your code) too:
int count = 0; boost::mutex mutex;
void increment_count() { boost::mutex::scoped_lock lock(mutex); std::cout << "count = " << ++count << std::endl; }
int main(int argc, char* argv[]) { boost::thread_group threads; for (int i = 0; i < 10; ++i) threads.create_thread(&increment_count); threads.join_all(); }
This suggests that valgrind might give false race warnings for boost thread code. Although I am not 100% sure of it. BTW, what other debugging tools are available to us for debugging boost threaded code?
Robert
On Wed, Nov 24, 2010 at 11:05 AM, Kraus Philipp <philipp.kraus@flashpixx.de> wrote:
Hello, I have written this little example: boost::mutex mutex; void thread() { for (int i = 0; i < 5; ++i) { boost::this_thread::sleep(boost::posix_time::seconds(3)); boost::lock_guard<boost::mutex> lock(mutex); std::cout << "Thread " << boost::this_thread::get_id() << ": " << i << std::endl; } } int main(int argc, char *argv[]) { boost::thread t1(thread); boost::thread t2(thread); t1.join(); t2.join(); } I compile the code with pthread option on the gcc (4.0.1). In the first case the program works, but if I use the helgrind tool of valgrind I'll get this errors (sorry for the long messages). I would like to understand what I have done wrong. I hope I understand the lock_guard in the correct way: If I create the lock with the mutex variable the thread, that creates the lock runs down the next lines. All other threads that run into the lock_guard line blocks until the lock variable of the first thread call the destructor (which should be on every loop iteration). Thanks for help Phil
------Valgrind Logs-----------
==19846== Thread #1 is the program's root thread ==19846== Thread #3 & #2 was created ==19846== at 0x15A1FDE: __bsdthread_create (in /usr/lib/libSystem.B.dylib) ==19846== by 0x378F4: pthread_create_WRK (hg_intercepts.c:257) ==19846== by 0x379C8: pthread_create (hg_intercepts.c:294) ==19846== by 0x55C06: boost::thread::start_thread() (in libboost_thread.dylib) ==19846== by 0x9FED: boost::thread::thread<void (*)()>(void (*)(), boost::disable_if<boost::is_convertible<void (*&)(), boost::detail::thread_move_t<void (*)()> >, boost::thread::dummy*>::type) (in ./main) ==19846== by 0x2A82: main (in ./main) This message is show for thread #1, #2 and #3 ==19846== Possible data race during read of size 4 at 0x5e008 by thread #3 ==19846== at 0x56381: void boost::call_once<void (*)()>(boost::once_flag&, void (*)()) (in libboost_thread.dylib) ==19846== by 0x545AC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib) ==19846== This conflicts with a previous write of size 4 by thread #2 ==19846== at 0x5647F: void boost::call_once<void (*)()>(boost::once_flag&, void (*)()) (in /libboost_thread.dylib) ==19846== by 0x545AC: thread_proxy (in /libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib) ==19846== Thread #2: Bug in libpthread: recursive write lock granted on mutex/wrlock which does not support recursion ==19846== at 0x385D2: pthread_cond_timedwait_WRK (hg_intercepts.c:764) ==19846== by 0x386B0: pthread_cond_timedwait$* (hg_intercepts.c:798) ==19846== by 0x5AABB: boost::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost::this_thread::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib) The next message is shown for the thread #2 & #3 ==19846== Thread #3: lock order "0x2500668 before 0x25005C8" violated ==19846== at 0x37E1B: pthread_mutex_lock (hg_intercepts.c:496) ==19846== by 0x5ABA3: boost::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost::this_thread::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib) ==19846== Required order was established by acquisition of lock at 0x2500668 ==19846== at 0x37E1B: pthread_mutex_lock (hg_intercepts.c:496) ==19846== by 0x15A3452: _pthread_cond_wait (in /usr/lib/libSystem.B.dylib) ==19846== by 0x15C89F7: pthread_cond_timedwait$UNIX2003 (in /usr/lib/libSystem.B.dylib) ==19846== by 0x38575: pthread_cond_timedwait_WRK (hg_intercepts.c:760) ==19846== by 0x386B0: pthread_cond_timedwait$* (hg_intercepts.c:798) ==19846== by 0x5AABB: boost::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost::this_thread::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib) ==19846== followed by a later acquisition of lock at 0x25005C8 ==19846== at 0x37E1B: pthread_mutex_lock (hg_intercepts.c:496) ==19846== by 0x53E6A: boost::this_thread::interruption_point() (in libboost_thread.dylib) ==19846== by 0x5AAC2: boost::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in /libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost::this_thread::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/libSystem.B.dylib)
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Hi Robert, Am 25.11.2010 um 04:48 schrieb Boost lzw:
Hi, Phil,
Valgrind user manual give no more information than " Applications that use the Boost.Thread library should run fine under DRD." I ran your code using DRD tool of valgrind and got race warnings too.
I then ran the following thread_group.cpp code distributed with boost_1_42, debugged it with valgrind --tool=drd, and it gave race warnings (more errors than your code) too:
Yes, the same things here. I tested the code with Boost 1.44 and 1.45 on OSX and Gentoo Linux. }
This suggests that valgrind might give false race warnings for boost thread code. Although I am not 100% sure of it.
If there are only false-positivies, I would ignore this error. I think so, because the code works fine and in my data structures are no errors Thx Phil
On Wed, Nov 24, 2010 at 11:05 AM, Kraus Philipp <philipp.kraus@flashpixx.de
wrote: Hello,
I have written this little example:
boost::mutex mutex;
void thread() { for (int i = 0; i < 5; ++i) { boost::this_thread::sleep(boost::posix_time::seconds(3)); boost::lock_guard<boost::mutex> lock(mutex); std::cout << "Thread " << boost::this_thread::get_id() << ": " << i << std::endl; } }
int main(int argc, char *argv[]) { boost::thread t1(thread); boost::thread t2(thread); t1.join(); t2.join(); }
I compile the code with pthread option on the gcc (4.0.1). In the first case the program works, but if I use the helgrind tool of valgrind I'll get this errors (sorry for the long messages). I would like to understand what I have done wrong. I hope I understand the lock_guard in the correct way: If I create the lock with the mutex variable the thread, that creates the lock runs down the next lines. All other threads that run into the lock_guard line blocks until the lock variable of the first thread call the destructor (which should be on every loop iteration).
Thanks for help
Phil
------Valgrind Logs-----------
==19846== Thread #1 is the program's root thread
==19846== Thread #3 & #2 was created ==19846== at 0x15A1FDE: __bsdthread_create (in /usr/lib/ libSystem.B.dylib) ==19846== by 0x378F4: pthread_create_WRK (hg_intercepts.c:257) ==19846== by 0x379C8: pthread_create (hg_intercepts.c:294) ==19846== by 0x55C06: boost::thread::start_thread() (in libboost_thread.dylib) ==19846== by 0x9FED: boost::thread::thread<void (*)()>(void (*) (), boost::disable_if<boost::is_convertible<void (*&)(), boost::detail::thread_move_t<void (*)()> >, boost::thread::dummy*>::type) (in ./main) ==19846== by 0x2A82: main (in ./main)
This message is show for thread #1, #2 and #3
==19846== Possible data race during read of size 4 at 0x5e008 by thread #3 ==19846== at 0x56381: void boost::call_once<void (*) ()>(boost::once_flag&, void (*)()) (in libboost_thread.dylib) ==19846== by 0x545AC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/ libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/ libSystem.B.dylib) ==19846== This conflicts with a previous write of size 4 by thread #2 ==19846== at 0x5647F: void boost::call_once<void (*) ()>(boost::once_flag&, void (*)()) (in /libboost_thread.dylib) ==19846== by 0x545AC: thread_proxy (in /libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/ libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/ libSystem.B.dylib)
==19846== Thread #2: Bug in libpthread: recursive write lock granted on mutex/wrlock which does not support recursion ==19846== at 0x385D2: pthread_cond_timedwait_WRK (hg_intercepts.c: 764) ==19846== by 0x386B0: pthread_cond_timedwait$* (hg_intercepts.c: 798) ==19846== by 0x5AABB: boost ::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost ::this_thread ::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/ libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/ libSystem.B.dylib)
The next message is shown for the thread #2 & #3
==19846== Thread #3: lock order "0x2500668 before 0x25005C8" violated ==19846== at 0x37E1B: pthread_mutex_lock (hg_intercepts.c:496) ==19846== by 0x5ABA3: boost ::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost ::this_thread ::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/ libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/ libSystem.B.dylib) ==19846== Required order was established by acquisition of lock at 0x2500668 ==19846== at 0x37E1B: pthread_mutex_lock (hg_intercepts.c:496) ==19846== by 0x15A3452: _pthread_cond_wait (in /usr/lib/ libSystem.B.dylib) ==19846== by 0x15C89F7: pthread_cond_timedwait$UNIX2003 (in /usr/ lib/libSystem.B.dylib) ==19846== by 0x38575: pthread_cond_timedwait_WRK (hg_intercepts.c: 760) ==19846== by 0x386B0: pthread_cond_timedwait$* (hg_intercepts.c: 798) ==19846== by 0x5AABB: boost ::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost ::this_thread ::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/ libSystem.B.dylib) ==19846== followed by a later acquisition of lock at 0x25005C8 ==19846== at 0x37E1B: pthread_mutex_lock (hg_intercepts.c:496) ==19846== by 0x53E6A: boost::this_thread::interruption_point() (in libboost_thread.dylib) ==19846== by 0x5AAC2: boost ::condition_variable::timed_wait(boost::unique_lock<boost::mutex>&, boost::posix_time::ptime const&) (in /libboost_thread.dylib) ==19846== by 0x54DC5: boost::this_thread::sleep(boost::posix_time::ptime const&) (in libboost_thread.dylib) ==19846== by 0xEE31: void boost ::this_thread ::sleep<boost::posix_time::seconds>(boost::posix_time::seconds const&) (in ./main) ==19846== by 0x23F8: thread() (in ./main) ==19846== by 0x545CC: thread_proxy (in libboost_thread.dylib) ==19846== by 0x37828: mythread_wrapper (hg_intercepts.c:221) ==19846== by 0x15A2154: _pthread_start (in /usr/lib/ libSystem.B.dylib) ==19846== by 0x15A2011: thread_start (in /usr/lib/ libSystem.B.dylib)
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participants (3)
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Boost lzw -
Brian Budge -
Kraus Philipp