Hello grinders.
So, I find it difficult to see the race. Below, the valgrind DRD output follows:
**************************************************************
Conflicting load by thread 1 at 0x1221c91c size 4
==4907== at 0x5B7028: Parallel_Mesh_Generation::try_lock(Vertex*,
int) (Parallel_Mesh_Generation.cxx:2224)
......
Other segment start (thread 9)
==4907== at 0x4C352A0: pthread_mutex_unlock (drd_pthread_intercepts.c:665)
==4907== by 0x5CB1E9: boost::mutex::unlock() (mutex.hpp:61)
==4907== by 0x5C96DE: Parallel_Mesh_Generation::UpdateNewCells(int,
Simple_Containers::Vector<Cell*>&) (Parallel_Mesh_Generation.cxx:8909)
==4907== by 0x5B3FC7: Parallel_Mesh_Generation::client_insert(int
const&, Point const&, Cell*) (Parallel_Mesh_Generation.cxx:790)
Other segment end (thread 9)
==4907== at 0x6E13464: __lll_lock_wait (lowlevellock.S:136)
==4907== by 0x6E0E5D8: _L_lock_953 (pthread_mutex_lock.c:117)
==4907== by 0x6E0E3F9: pthread_mutex_lock (pthread_mutex_lock.c:61)
==4907== by 0x4C362AF: pthread_mutex_lock (drd_pthread_intercepts.c:614)
==4907== by 0x5CB182: boost::mutex::lock() (mutex.hpp:52)
==4907== by 0x5C9661: Parallel_Mesh_Generation::UpdateNewCells(int,
Simple_Containers::Vector<Cell*>&) (Parallel_Mesh_Generation.cxx:8900)
==4907== by 0x5B3FC7: Parallel_Mesh_Generation::client_insert(int
const&, Point const&, Cell*) (Parallel_Mesh_Generation.cxx:790)
**************************************************************
According to DRD, there is a race when thead 1 is at line 2224, and
thread 9 is at the lines 8900-8909, correct?
Below, the relevant code lines are attached:
**************************************************************
Thread 1:
if(v->thread_id == thread_id)
//line 2224
**************************************************************
and
**************************************************************
Thread 9:
this->utilization_mtx.lock();
//line 8900
if(this->threads_without_work != 0)
{
this->threads_without_work--;
#ifdef REPORT_COUNTERS
(*this->begging_list_not_empty[thread_id])++;
#endif
other_id =
this->beggers[(this->beg_index_start++)%this->number_of_threads];
this->utilization_mtx.unlock(); //line
8909
**************************************************************
The variable "thread_id" in Thread 9 is local to its stack. It has
nothing to do with either "v->thread_id" or "thread_id" of Thread 1.
Is this a false positive, or the drd message says something else?
Regards,
Panagiotis Foteinos
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