[issue40860] Exception in multiprocessing/context.py under load

[Arkady]

Arkady <larytet at gmail.com> added the comment:

A workaround is to synchronize the call to Process.start()

diff --git a/main.py b/main.py
index d09dc53..49d68f0 100644
--- a/main.py
+++ b/main.py
@@ -26,17 +26,24 @@ def load_cpu(deadline):
     while time.time() - start < 0.2*deadline:
         math.pow(random.randint(0, 1), random.randint(0, 1))

+def join_process(job, timeout):
+    time_start = time.time()
+    while time.time()-time_start < timeout and job.is_alive():
+        time.sleep(0.1   * timeout)
+        continue
+
 job_counter = 0
+lock = threading.Lock()
 def spawn_job(deadline):
     '''
     Creat a new Process, call join(), process errors
     '''    
     global job_counter
     time_start = time.time()
-    job = multiprocessing.Process(target=load_cpu, args=(deadline, ))
-    job.start()
-    # timeout=None in the call to join() solves the problem
-    job.join(deadline)
+    with lock:
+        job = multiprocessing.Process(target=load_cpu, args=(deadline, ))
+        job.start()
+    join_process(job, deadline)

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue40860>
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