#3526 closed Bugs (invalid)
Data races in boost::thread detected by drd/helgrind
| Reported by: | Owned by: | Anthony Williams | |
|---|---|---|---|
| Milestone: | To Be Determined | Component: | thread |
| Version: | Boost Development Trunk | Severity: | Regression |
| Keywords: | valgrind, drd, threading | Cc: | bvanassche@… |
Description
OS: Ubuntu Jaunty, 64-bit
Valgrind version: 3.4.1
There are data races detected by valgrind tools drd and helgrind in boost::thread library examples. Problem appears in boost 1.37-1.40 at least and everything runs just fine in boost 1.34 (hard to test more versions, my work PC is not so fast and building takes a lot of time).
Test cases:
1) thread_group.cpp example from boost library
2) attached file, my own minimal test case that provoked exploration
Attachments (1)
Change History (12)
by , 13 years ago
comment:2 by , 13 years ago
Yes, of course. Here is the output for current boost svn version (now in Arch Linux): {BUILD}
make all Building file: ../src/test.cpp Invoking: GCC C++ Compiler g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/test.d" -MT"src/test.d" -o"src/test.o" "../src/test.cpp" Finished building: ../src/test.cpp Building target: test Invoking: GCC C++ Linker g++ -o"test" ./src/test.o -lboost_thread Finished building target: test
{RUN}
[mist@mist-pc test]$ valgrind --tool=drd ./Debug/test ==13143== drd, a thread error detector ==13143== Copyright (C) 2006-2009, and GNU GPL'd, by Bart Van Assche. ==13143== Using Valgrind-3.5.0 and LibVEX; rerun with -h for copyright info ==13143== Command: ./Debug/test ==13143== ==13143== Thread 3: ==13143== Conflicting load by thread 3 at 0x05043df0 size 8 ==13143== at 0x4E3A684: ??? (in /usr/local/lib/libboost_thread.so.1.41.0) ==13143== by 0x4E3AA88: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/local/lib/libboost_thread.so.1.41.0) ==13143== by 0x4E3B084: thread_proxy (in /usr/local/lib/libboost_thread.so.1.41.0) ==13143== by 0x4C2CC70: vgDrd_thread_wrapper (in /usr/lib/valgrind/vgpreload_drd-amd64-linux.so) ==13143== by 0x5D4B579: start_thread (in /lib/libpthread-2.10.1.so) ==13143== by 0x58B514C: clone (in /lib/libc-2.10.1.so) ==13143== Allocation context: BSS section of /usr/local/lib/libboost_thread.so.1.41.0 ==13143== Other segment start (thread 2) ==13143== at 0x4C25533: pthread_mutex_lock (in /usr/lib/valgrind/vgpreload_drd-amd64-linux.so) ==13143== by 0x4E3A73D: ??? (in /usr/local/lib/libboost_thread.so.1.41.0) ==13143== by 0x4E3AA88: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/local/lib/libboost_thread.so.1.41.0) ==13143== by 0x4E3B084: thread_proxy (in /usr/local/lib/libboost_thread.so.1.41.0) ==13143== by 0x4C2CC70: vgDrd_thread_wrapper (in /usr/lib/valgrind/vgpreload_drd-amd64-linux.so) ==13143== by 0x5D4B579: start_thread (in /lib/libpthread-2.10.1.so) ==13143== by 0x58B514C: clone (in /lib/libc-2.10.1.so) ==13143== Other segment end (thread 2) ==13143== at 0x4C2615F: pthread_mutex_unlock (in /usr/lib/valgrind/vgpreload_drd-amd64-linux.so) ==13143== by 0x4E3AA88: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/local/lib/libboost_thread.so.1.41.0) ==13143== by 0x4E3B084: thread_proxy (in /usr/local/lib/libboost_thread.so.1.41.0) ==13143== by 0x4C2CC70: vgDrd_thread_wrapper (in /usr/lib/valgrind/vgpreload_drd-amd64-linux.so) ==13143== by 0x5D4B579: start_thread (in /lib/libpthread-2.10.1.so) ==13143== by 0x58B514C: clone (in /lib/libc-2.10.1.so) ==13143== Other segment start (thread 2) ==13143== at 0x4C25533: pthread_mutex_lock (in /usr/lib/valgrind/vgpreload_drd-amd64-linux.so) ==13143== by 0x4E3A6AB: ??? (in /usr/local/lib/libboost_thread.so.1.41.0) ==13143== by 0x4E3AA88: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/local/lib/libboost_thread.so.1.41.0) ==13143== by 0x4E3B084: thread_proxy (in /usr/local/lib/libboost_thread.so.1.41.0) ==13143== by 0x4C2CC70: vgDrd_thread_wrapper (in /usr/lib/valgrind/vgpreload_drd-amd64-linux.so) ==13143== by 0x5D4B579: start_thread (in /lib/libpthread-2.10.1.so) ==13143== by 0x58B514C: clone (in /lib/libc-2.10.1.so) ==13143== Other segment end (thread 2) ==13143== at 0x4C2615F: pthread_mutex_unlock (in /usr/lib/valgrind/vgpreload_drd-amd64-linux.so) ==13143== by 0x4E3A722: ??? (in /usr/local/lib/libboost_thread.so.1.41.0) ==13143== by 0x4E3AA88: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/local/lib/libboost_thread.so.1.41.0) ==13143== by 0x4E3B084: thread_proxy (in /usr/local/lib/libboost_thread.so.1.41.0) ==13143== by 0x4C2CC70: vgDrd_thread_wrapper (in /usr/lib/valgrind/vgpreload_drd-amd64-linux.so) ==13143== by 0x5D4B579: start_thread (in /lib/libpthread-2.10.1.so) ==13143== by 0x58B514C: clone (in /lib/libc-2.10.1.so) ==13143== ==13143== ==13143== For counts of detected and suppressed errors, rerun with: -v ==13143== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 34 from 29)
comment:4 by , 13 years ago
Okay. The problem is [source:trunk/boost/thread/pthread/once.hpp@45865#L49 once.hpp line 49] and [source:trunk/boost/thread/pthread/once.hpp@45865#L72 once.hpp line 72]. For this to work, we need atomic read and write. I'm not sure whether this is a real problem or not. At least it should be explicit.
comment:5 by , 13 years ago
Thanks! Mhm, if it will be stated as a not-real-problem, may be it is possible to contact with valgrind developers to give ability to switch off such message? It makes rather difficult to debug real thread usage errors.
follow-up: 7 comment:6 by , 12 years ago
| Cc: | added |
|---|---|
| Severity: | Regression → Problem |
| Version: | Boost 1.40.0 → Boost Development Trunk |
This is a real bug. With the current implementation it is possible that call_once() invokes its second argument (Function f) twice. flag.epoch should be tested again after detail::once_epoch_mutex has been locked, just like as when applying the double-checked optimization to the singleton pattern.
comment:7 by , 12 years ago
Replying to bvanassche@…:
This is a real bug. With the current implementation it is possible that call_once() invokes its second argument (Function f) twice. flag.epoch should be tested again after detail::once_epoch_mutex has been locked, just like as when applying the double-checked optimization to the singleton pattern.
Please ignore the above comment -- I overlooked the pthread_mutex_scoped_lock statement near the beginning of call_once() which guarantees thread-safe updating of flag.epoch and also that f() is invoked by only one thread.
comment:8 by , 12 years ago
| Resolution: | → invalid |
|---|---|
| Severity: | Problem → Regression |
| Status: | new → closed |
The reason DRD printed the above report is as follows:
- boost::detail::get_current_thread_data() and boost::detail::set_current_thread_data() both invoke boost::call_once(current_thread_tls_init_flag,create_current_thread_tls_key) and next use current_thread_tls_key.
- The first call of boost::call_once() invokes create_current_thread_tls_key() and hence sets current_thread_tls_key. This last function is invoked without holding the mutex detail::once_epoch_mutex.
- The second and subsequent invocations of boost::call_once() neither lock detail::once_epoch_mutex nor trigger a call to create_current_thread_tls_key().
Or: although every read of current_thread_tls_key happens after its initialization, this ordering is invisible to data race detection tools. That's why DRD complains about it. A suppression pattern for this access pattern will be added in Valgrind 3.6.0.
comment:9 by , 11 years ago
I still get the data race reports with valgrind-3.6.1. Did the suppression pattern not get into valgrind 3.6? Or is there another problem?
comment:10 by , 11 years ago
An appropriate suppression pattern was added in glibc-2.X-drd.supp via SVN revisions 8848, 10684 and 11152. As far as I can see these changes are present in Valgrind 3.6.0. Note: these changes only affect DRD but not Helgrind.
comment:11 by , 11 years ago
I get the following output with valgrind 3.6.1 and drd:
[froth@megaera ~]$ valgrind --tool=drd ./a.out ==9839== drd, a thread error detector ==9839== Copyright (C) 2006-2010, and GNU GPL'd, by Bart Van Assche. ==9839== Using Valgrind-3.6.1 and LibVEX; rerun with -h for copyright info ==9839== Command: ./a.out ==9839== ==9839== Thread 3: ==9839== Conflicting load by thread 3 at 0x040431ec size 4 ==9839== at 0x4035873: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== Allocation context: BSS section of /usr/lib/libboost_thread-mt.so.1.47.0 ==9839== Other segment start (thread 2) ==9839== at 0x400AC73: pthread_mutex_lock (drd_pthread_intercepts.c:587) ==9839== by 0x42E63C03: pthread_mutex_lock (in /lib/libc-2.14.90.so) ==9839== by 0x403595B: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x4035B84: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== Other segment end (thread 2) ==9839== at 0x400B508: pthread_mutex_unlock (drd_pthread_intercepts.c:640) ==9839== by 0x42E63C43: pthread_mutex_unlock (in /lib/libc-2.14.90.so) ==9839== by 0x40358CD: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x4035B84: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== Other segment start (thread 2) ==9839== at 0x400AC73: pthread_mutex_lock (drd_pthread_intercepts.c:587) ==9839== by 0x42E63C03: pthread_mutex_lock (in /lib/libc-2.14.90.so) ==9839== by 0x403589A: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x4035B84: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== Other segment end (thread 2) ==9839== at 0x400B508: pthread_mutex_unlock (drd_pthread_intercepts.c:640) ==9839== by 0x42E63C43: pthread_mutex_unlock (in /lib/libc-2.14.90.so) ==9839== by 0x403593B: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x4035B84: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== ==9839== Conflicting load by thread 3 at 0x040431e8 size 4 ==9839== at 0x4035879: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== Allocation context: BSS section of /usr/lib/libboost_thread-mt.so.1.47.0 ==9839== Other segment start (thread 2) ==9839== at 0x400AC73: pthread_mutex_lock (drd_pthread_intercepts.c:587) ==9839== by 0x42E63C03: pthread_mutex_lock (in /lib/libc-2.14.90.so) ==9839== by 0x403595B: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x4035B84: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== Other segment end (thread 2) ==9839== at 0x400B508: pthread_mutex_unlock (drd_pthread_intercepts.c:640) ==9839== by 0x42E63C43: pthread_mutex_unlock (in /lib/libc-2.14.90.so) ==9839== by 0x40358CD: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x4035B84: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== Other segment start (thread 2) ==9839== at 0x400AC73: pthread_mutex_lock (drd_pthread_intercepts.c:587) ==9839== by 0x42E63C03: pthread_mutex_lock (in /lib/libc-2.14.90.so) ==9839== by 0x403589A: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x4035B84: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== Other segment end (thread 2) ==9839== at 0x400B508: pthread_mutex_unlock (drd_pthread_intercepts.c:640) ==9839== by 0x42E63C43: pthread_mutex_unlock (in /lib/libc-2.14.90.so) ==9839== by 0x403593B: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x4035B84: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== ==9839== Thread 1: ==9839== Conflicting load by thread 1 at 0x040431ec size 4 ==9839== at 0x4035873: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42D7C6B2: (below main) (in /lib/libc-2.14.90.so) ==9839== Allocation context: BSS section of /usr/lib/libboost_thread-mt.so.1.47.0 ==9839== Other segment start (thread 2) ==9839== at 0x400B508: pthread_mutex_unlock (drd_pthread_intercepts.c:640) ==9839== by 0x42E63C43: pthread_mutex_unlock (in /lib/libc-2.14.90.so) ==9839== by 0x403593B: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x4035B84: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== Other segment end (thread 2) ==9839== at 0x400B508: pthread_mutex_unlock (drd_pthread_intercepts.c:640) ==9839== by 0x42E63C43: pthread_mutex_unlock (in /lib/libc-2.14.90.so) ==9839== by 0x40358CD: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x4035B84: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== Other segment start (thread 2) ==9839== at 0x42E55828: clone (in /lib/libc-2.14.90.so) ==9839== Other segment end (thread 2) ==9839== at 0x400B508: pthread_mutex_unlock (drd_pthread_intercepts.c:640) ==9839== by 0x42E63C43: pthread_mutex_unlock (in /lib/libc-2.14.90.so) ==9839== by 0x403593B: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x4035B84: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== ==9839== Conflicting load by thread 1 at 0x040431e8 size 4 ==9839== at 0x4035879: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42D7C6B2: (below main) (in /lib/libc-2.14.90.so) ==9839== Allocation context: BSS section of /usr/lib/libboost_thread-mt.so.1.47.0 ==9839== Other segment start (thread 2) ==9839== at 0x400B508: pthread_mutex_unlock (drd_pthread_intercepts.c:640) ==9839== by 0x42E63C43: pthread_mutex_unlock (in /lib/libc-2.14.90.so) ==9839== by 0x403593B: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x4035B84: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== Other segment end (thread 2) ==9839== at 0x400B508: pthread_mutex_unlock (drd_pthread_intercepts.c:640) ==9839== by 0x42E63C43: pthread_mutex_unlock (in /lib/libc-2.14.90.so) ==9839== by 0x40358CD: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x4035B84: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== Other segment start (thread 2) ==9839== at 0x42E55828: clone (in /lib/libc-2.14.90.so) ==9839== Other segment end (thread 2) ==9839== at 0x400B508: pthread_mutex_unlock (drd_pthread_intercepts.c:640) ==9839== by 0x42E63C43: pthread_mutex_unlock (in /lib/libc-2.14.90.so) ==9839== by 0x403593B: ??? (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x4035B84: boost::detail::set_current_thread_data(boost::detail::thread_data_base*) (in /usr/lib/libboost_thread-mt.so.1.47.0) ==9839== by 0x42F17CD2: start_thread (in /lib/libpthread-2.14.90.so) ==9839== by 0x42E5583D: clone (in /lib/libc-2.14.90.so) ==9839== ==9839== ==9839== For counts of detected and suppressed errors, rerun with: -v ==9839== ERROR SUMMARY: 4 errors from 4 contexts (suppressed: 42 from 22)
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My test case to run with valgrind