Le 24/04/15 21:17, Ben Pope a écrit :
On Tuesday, April 21, 2015 06:42 PM, Ben Pope wrote:
89 SUMMARY: ThreadSanitizer: data race /home/ben/development/boost/test/build/boost_root/status/../boost/smart_ptr/detail/shared_count.hpp:449:49
in boost::detail::shared_count::shared_count(boost::detail::shared_count const&)
I've just been looking at this one, essentially it seems to boil down to:
#include <atomic> #include <thread> #include <cstdint>
typedef _Atomic( std::int_least32_t ) atomic_int_least32_t;
inline void atomic_increment( atomic_int_least32_t * pw ) { __c11_atomic_fetch_add( pw, 1, __ATOMIC_RELAXED ); }
int main() { atomic_int_least32_t use_count_; std::thread t ([&](){ atomic_increment(&use_count_); }); __c11_atomic_init( &use_count_, 1 ); t.join(); }
The Boost.Thread code is different static void* thread_proxy(void* param) { boost::detail::thread_data_ptr thread_info = static_castboost::detail::thread_data_base*(param)->self; // (2) bool thread::start_thread_noexcept() { thread_info->self=thread_info; // (1) int const res = pthread_create(&thread_info->thread_handle, 0, &thread_proxy, thread_info.get()); if (res != 0) { thread_info->self.reset(); // (3) return false; } The thread context thread_info stores a smart_ptr to itself in member self (1). if the thread creation succeeds, self is used (2) Only if the thread creation fails, the self member is reset (3). I don't see where the data race is. I have changed (2) by boost::detail::thread_data_ptr thread_info = static_castboost::detail::thread_data_base*(param)->shared_from_this(); thread_info->self.reset(); Lets see what ThreadSanitizer reports after this change. https://github.com/boostorg/thread/commit/0218136ed7df26b66ec64cec1f7195b83e... Best, Vicente