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Make size of the Python futures pool in ucxx::Worker configurable #11

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pentschev opened this issue Apr 3, 2023 · 0 comments
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If requests for Python futures from the worker pool happen too quickly, it may lead to warnings, for example in test_multiple_nodes.py::test_many_servers_many_clients. Making the size configurable will potentially allow for better performance and to circumvent those warnings.

@pentschev pentschev added the feature request New feature or request label Apr 3, 2023
rapids-bot bot pushed a commit that referenced this issue Dec 5, 2023
It is unclear why but for some reason `notify_all()` is causing futexes never to return in some situations. This occurs very frequently in CI and is also less frequently reproducible locally.

The typical stack trace for the blocked thread is shown below:

```cpp
Thread 6 (Thread 0x7f13ec84f700 (LWP 2823667) "pytest"):
#0  futex_wait (private=<optimized out>, expected=32765, futex_word=0x7ffd5186a874) at ../sysdeps/nptl/futex-internal.h:141
#1  futex_wait_simple (private=<optimized out>, expected=32765, futex_word=0x7ffd5186a874) at ../sysdeps/nptl/futex-internal.h:172
#2  __condvar_quiesce_and_switch_g1 (private=<optimized out>, g1index=<synthetic pointer>, wseq=<optimized out>, cond=0x7ffd5186a860) at pthread_cond_common.c:416
#3  __pthread_cond_broadcast (cond=0x7ffd5186a860) at pthread_cond_broadcast.c:73
#4  0x00007f140fe5f23c in ucxx::BaseDelayedSubmissionCollection<std::function<void ()> >::process() (this=0x560d0effafd0) at /repo/cpp/include/ucxx/delayed_submission.h:154
#5  0x00007f140fe5f399 in ucxx::DelayedSubmissionCollection::processPost (this=<optimized out>) at /repo/cpp/src/delayed_submission.cpp:84
#6  0x00007f140fe7ed71 in ucxx::WorkerProgressThread::progressUntilSync(std::function<bool ()>, bool const&, std::function<void (void*)>, void*, std::shared_ptr<ucxx::DelayedSubmissionCollection>) (progressFunction=..., stop=@0x560d0f6527f8: false, startCallback=..., startCallbackArg=<optimized out>, delayedSubmissionCollection=...) at /opt/conda/envs/test/x86_64-conda-linux-gnu/include/c++/11.4.0/bits/shared_ptr_base.h:1295
#7  0x00007f140fe7f3ee in std::__invoke_impl<void, void (*)(std::function<bool ()>, bool const&, std::function<void (void*)>, void*, std::shared_ptr<ucxx::DelayedSubmissionCollection>), std::function<bool ()>, std::reference_wrapper<bool>, std::function<void (void*)>, void*, std::shared_ptr<ucxx::DelayedSubmissionCollection> >(std::__invoke_other, void (*&&)(std::function<bool ()>, bool const&, std::function<void (void*)>, void*, std::shared_ptr<ucxx::DelayedSubmissionCollection>), std::function<bool ()>&&, std::reference_wrapper<bool>&&, std::function<void (void*)>&&, void*&&, std::shared_ptr<ucxx::DelayedSubmissionCollection>&&) (__f=<optimized out>, __f=<optimized out>) at /opt/conda/envs/test/x86_64-conda-linux-gnu/include/c++/11.4.0/bits/invoke.h:61
#8  std::__invoke<void (*)(std::function<bool ()>, bool const&, std::function<void (void*)>, void*, std::shared_ptr<ucxx::DelayedSubmissionCollection>), std::function<bool ()>, std::reference_wrapper<bool>, std::function<void (void*)>, void*, std::shared_ptr<ucxx::DelayedSubmissionCollection> >(void (*&&)(std::function<bool ()>, bool const&, std::function<void (void*)>, void*, std::shared_ptr<ucxx::DelayedSubmissionCollection>), std::function<bool ()>&&, std::reference_wrapper<bool>&&, std::function<void (void*)>&&, void*&&, std::shared_ptr<ucxx::DelayedSubmissionCollection>&&) (__fn=<optimized out>) at /opt/conda/envs/test/x86_64-conda-linux-gnu/include/c++/11.4.0/bits/invoke.h:96
#9  std::thread::_Invoker<std::tuple<void (*)(std::function<bool ()>, bool const&, std::function<void (void*)>, void*, std::shared_ptr<ucxx::DelayedSubmissionCollection>), std::function<bool ()>, std::reference_wrapper<bool>, std::function<void (void*)>, void*, std::shared_ptr<ucxx::DelayedSubmissionCollection> > >::_M_invoke<0ul, 1ul, 2ul, 3ul, 4ul, 5ul>(std::_Index_tuple<0ul, 1ul, 2ul, 3ul, 4ul, 5ul>) (this=<optimized out>) at /opt/conda/envs/test/x86_64-conda-linux-gnu/include/c++/11.4.0/bits/std_thread.h:259
#10 std::thread::_Invoker<std::tuple<void (*)(std::function<bool ()>, bool const&, std::function<void (void*)>, void*, std::shared_ptr<ucxx::DelayedSubmissionCollection>), std::function<bool ()>, std::reference_wrapper<bool>, std::function<void (void*)>, void*, std::shared_ptr<ucxx::DelayedSubmissionCollection> > >::operator()() (this=<optimized out>) at /opt/conda/envs/test/x86_64-conda-linux-gnu/include/c++/11.4.0/bits/std_thread.h:266
#11 std::thread::_State_impl<std::thread::_Invoker<std::tuple<void (*)(std::function<bool ()>, bool const&, std::function<void (void*)>, void*, std::shared_ptr<ucxx::DelayedSubmissionCollection>), std::function<bool ()>, std::reference_wrapper<bool>, std::function<void (void*)>, void*, std::shared_ptr<ucxx::DelayedSubmissionCollection> > > >::_M_run() (this=<optimized out>) at /opt/conda/envs/test/x86_64-conda-linux-gnu/include/c++/11.4.0/bits/std_thread.h:211
#12 0x00007f140f92fe95 in std::execute_native_thread_routine (__p=<optimized out>) at ../../../../../libstdc++-v3/src/c++11/thread.cc:104
#13 0x00007f1412647609 in start_thread (arg=<optimized out>) at pthread_create.c:477
#14 0x00007f1412412133 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
```

Authors:
  - Peter Andreas Entschev (https://github.com/pentschev)

Approvers:
  - Lawrence Mitchell (https://github.com/wence-)

URL: #140
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