[issue31115] Py3.6 threading/reference counting issues with `numexpr`

[Robert McLeod]

New submission from Robert McLeod:

I'm working on the development branch of the `numexpr` module and I've run into some problems on Python 3.6, where I seem to get a variety of errors relating to threading or reference counting errors. This module is commonly used for accelerating NumPy code, as it can parse an expression into a C-extension virtual machine program and break the calculations down into blocks which are then dispatched over multiple threads. I get similar errors on both Ubuntu 16.04 with GCC5.4 and Win7 with MSVC2015.  I created an issue here where I provide some of the `gcc` error outputs.  

https://github.com/pydata/numexpr/issues/252

Typically I'm getting a different error on every run. 

We use a wrapper for Windows threads that emulated pthreads, and I found on Windows crashes occurred on calling the Windows system function `WaitForSingleObject(cond->sema, INFINITE);` in the file numexpr3/win32/pthread.c.  

I cannot replicate this problem in Python 2.7/3.4/3.5 on Windows or Linux. I'm using Anaconda in both instances, with nomkl NumPy on Linux and mkl NumPy on Windows.  

I tried valgrinding with Python 3.5 and 3.6, and I get numerous errors coming from places like pickle and ast (which the new NumExpr uses) in 3.6 and it's basically clean in 3.5.  The logs are attached to the issue linked above.

----------
components: Extension Modules, Library (Lib)
messages: 299722
nosy: Robert McLeod
priority: normal
severity: normal
status: open
title: Py3.6 threading/reference counting issues with `numexpr`
type: crash
versions: Python 3.6

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue31115>
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