Fix initialization of global_num_tasks in parallel_executor #4093
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hkaiser
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Sep 16, 2019
libs/execution/include/hpx/parallel/executors/parallel_executor.hpp
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hkaiser
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libs/execution/include/hpx/parallel/executors/parallel_executor.hpp
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Initializing the static variable global_num_tasks with hpx::get_os_thread_count() could lead to deadlocks when accessing the configuration option which contains the number of OS threads is contended. In this case the thread can be suspended while holding a lock for the static variable. This makes the variable non-static and gets the number of threads from the thread pool if inside an HPX thread. Otherwise it gets the number of threads for the default pool.
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Fixes deadlocks typically seen in the
1d_stencilexample caused by yielding while initializing a static variable. Details in commit message.Also initializes
global_num_tasksin theparallel_executorbased on the number of threads in the current pool (or default pool if not on an HPX thread).