Revert to default mpcontext

Use threadpoolctl to protect against deadlocks.

pyproject.toml

@@ -21,7 +21,7 @@ classifiers = [
     "Intended Audience :: Science/Research",
 ]
 dynamic = ["version"]
-dependencies = ["tblib"]
+dependencies = ["tblib", "threadpoolctl"]
 
 [project.optional-dependencies]
 tests = ["pytest", "pytest-timeout", "numpy", "pytest-coverage"]

seqtools/evaluation.py

@@ -1,5 +1,4 @@
 import functools
-import io
 import itertools
 import multiprocessing
 import os
@@ -14,6 +13,8 @@
 from abc import ABC, abstractmethod
 from multiprocessing import sharedctypes
 
+import threadpoolctl
+
 from tblib import pickling_support
 
 from .C.refcountedbuffer import RefCountedBuffer
@@ -63,7 +64,7 @@ def __init__(self, seq, num_workers=0, buffer_size=10, init_fn=None, shm_size=0)
             self.free_shm_slots = set()
 
         # initialize workers
-        mp_ctx = multiprocessing.get_context(method="spawn")  # spawn is OpenMP-friendly
+        mp_ctx = multiprocessing.get_context()
         self.job_queue = mp_ctx.Queue()
         self.result_pipes = []
 
@@ -85,7 +86,8 @@ def __init__(self, seq, num_workers=0, buffer_size=10, init_fn=None, shm_size=0)
                 daemon=True,
             )
             old_sig_hdl = signal.signal(signal.SIGINT, signal.SIG_IGN)
-            worker.start()
+            with threadpoolctl.threadpool_limits(limits=1):
+                worker.start()
             signal.signal(signal.SIGINT, old_sig_hdl)
             tx.close()