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How to catch exceptions raised by Python worker threads
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import Queue | |
import threading | |
class WorkerThread(threading.Thread): | |
def __init__(self, q): | |
super(WorkerThread, self).__init__() | |
self q = q | |
self.exception = None | |
def run(): | |
try: | |
while not self.q.empty(): | |
item = None | |
try: | |
item = self.q.get(False) | |
# do your stuff | |
except Queue.Empty: | |
pass | |
finally: | |
if item: | |
self.q.task_done() | |
except Exception as e: | |
self.exception = e | |
def get_exception(): | |
return self.exception | |
class MyClass: | |
def spawn_threads(self, q): | |
self.threads = [] | |
for _ in range(NUM_THREADS): | |
t = WorkerThread(q) | |
self.threads,append(t) | |
t.start() | |
def raise_thread_exceptions(): | |
for t in self.threads: | |
e = t.get_exception() | |
if e: | |
raise e | |
def my_func(self): | |
q = Queue.Queue() | |
# do something and q.put() | |
self.spawn_threads(q) | |
q.join() | |
# raise exceptions from worker threads | |
self.raise_thread_exceptions() |
L38: self.threads.append(t)
L8: self.q = q
there's a bug here when all threads are thrown and the q still isn't empty.
L55 should be:
for t in threads: t.join()
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Brilliant. Thanks.