Using gevent monkey patching with threading makes thread work serially
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When threads are monkey patched in gevent, they behave as coroutines. This means that you have to explicitly yield control to make it possible for other coroutines to execute.
The way to do this is call a blocking operation that has been patched (this will yield automatically) or gevent.sleep
:
#!/usr/bin/env python
from gevent import monkey, sleep
monkey.patch_all()
import threading
class ExampleThread(threading.Thread):
def run(self):
for i in xrange(10):
print 'working'
sleep()
if __name__ == '__main__':
worker = ExampleThread()
worker.start()
print 'this will be printed after the first call to sleep'
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Comments
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yossi about 4 years
I am using gevent and I am monkey patching everything.
It seems like the monkey patching causes the threading to work serially.My code:
import threading from gevent import monkey; monkey.patch_all() class ExampleThread(threading.Thread): def run(self): do_stuff() # takes a few minutes to finish print 'finished working' if __name__ == '__main__': worker = ExampleThread() worker.start() print 'this should be printed before the worker finished'
So the thread is not working as expected.
But if I remove themonkey.patch_all()
it is working fine.
The problem is that I need themonkey.patch_all()
for using gevent (now shown in the code above)My solution:
I changed the
monkey.patch_all()
to
monkey.patch_all(thread=False)
so I am not patching the thread.
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yossi over 12 yearsi have edited my question. i cant use sleep because my work takes a few minutes,
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jcollado over 12 years@yossi If you have a task that takes a long time to complete and isn't possible to yield control at some point, then you need real threads instead of coroutines. In such a case, I'd say you're better off not patching threads.
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Merlin almost 12 yearsI found this interesting. What would be the use case of this vs the standard theading module.
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jcollado almost 12 years@Merlin The motivation section in PEP342 might be a good source for that. In summary, threads aren't really cheap and if we need a lot of them, then it's worth considering alternatives.
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F79 almost 5 yearshow to use this?