How to make a Python generator execution asynchronous?











up vote
0
down vote

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I have a piece of of code that looks like this:



def generator():
while True:
result = very_long_computation()
yield result

def caller():
g = generator()
for i in range(n):
element = next(g)
another_very_long_computation()


Basically, I'd like to overlap the execution of very_long_computation() and another_very_long_computation() as much as possible.



Is there simple way to make the generator asynchronous? I'd like the generator to start computing the next iteration of the while loop right after result has been yielded, so that (ideally) the next result is ready to be yielded before the succesive next() call in caller().










share|improve this question


















  • 1




    FWIW, there's a very interesting video youtube tutorial by David Beazley titled A Curious Course on Coroutines and Concurrency from PyCon 2009 which you would probably find very enlightening.
    – martineau
    Nov 8 at 19:02






  • 1




    I'll check it out, thanks!
    – miditower
    Nov 9 at 13:06















up vote
0
down vote

favorite












I have a piece of of code that looks like this:



def generator():
while True:
result = very_long_computation()
yield result

def caller():
g = generator()
for i in range(n):
element = next(g)
another_very_long_computation()


Basically, I'd like to overlap the execution of very_long_computation() and another_very_long_computation() as much as possible.



Is there simple way to make the generator asynchronous? I'd like the generator to start computing the next iteration of the while loop right after result has been yielded, so that (ideally) the next result is ready to be yielded before the succesive next() call in caller().










share|improve this question


















  • 1




    FWIW, there's a very interesting video youtube tutorial by David Beazley titled A Curious Course on Coroutines and Concurrency from PyCon 2009 which you would probably find very enlightening.
    – martineau
    Nov 8 at 19:02






  • 1




    I'll check it out, thanks!
    – miditower
    Nov 9 at 13:06













up vote
0
down vote

favorite









up vote
0
down vote

favorite











I have a piece of of code that looks like this:



def generator():
while True:
result = very_long_computation()
yield result

def caller():
g = generator()
for i in range(n):
element = next(g)
another_very_long_computation()


Basically, I'd like to overlap the execution of very_long_computation() and another_very_long_computation() as much as possible.



Is there simple way to make the generator asynchronous? I'd like the generator to start computing the next iteration of the while loop right after result has been yielded, so that (ideally) the next result is ready to be yielded before the succesive next() call in caller().










share|improve this question













I have a piece of of code that looks like this:



def generator():
while True:
result = very_long_computation()
yield result

def caller():
g = generator()
for i in range(n):
element = next(g)
another_very_long_computation()


Basically, I'd like to overlap the execution of very_long_computation() and another_very_long_computation() as much as possible.



Is there simple way to make the generator asynchronous? I'd like the generator to start computing the next iteration of the while loop right after result has been yielded, so that (ideally) the next result is ready to be yielded before the succesive next() call in caller().







python asynchronous generator yield






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 8 at 18:46









miditower

173




173








  • 1




    FWIW, there's a very interesting video youtube tutorial by David Beazley titled A Curious Course on Coroutines and Concurrency from PyCon 2009 which you would probably find very enlightening.
    – martineau
    Nov 8 at 19:02






  • 1




    I'll check it out, thanks!
    – miditower
    Nov 9 at 13:06














  • 1




    FWIW, there's a very interesting video youtube tutorial by David Beazley titled A Curious Course on Coroutines and Concurrency from PyCon 2009 which you would probably find very enlightening.
    – martineau
    Nov 8 at 19:02






  • 1




    I'll check it out, thanks!
    – miditower
    Nov 9 at 13:06








1




1




FWIW, there's a very interesting video youtube tutorial by David Beazley titled A Curious Course on Coroutines and Concurrency from PyCon 2009 which you would probably find very enlightening.
– martineau
Nov 8 at 19:02




FWIW, there's a very interesting video youtube tutorial by David Beazley titled A Curious Course on Coroutines and Concurrency from PyCon 2009 which you would probably find very enlightening.
– martineau
Nov 8 at 19:02




1




1




I'll check it out, thanks!
– miditower
Nov 9 at 13:06




I'll check it out, thanks!
– miditower
Nov 9 at 13:06












1 Answer
1






active

oldest

votes

















up vote
3
down vote



accepted










There is no simple way, especially since you've got very_long_computation and another_very_long_computation instead of very_slow_io. Even if you moved generator into its own thread, you'd be limited by CPython's global interpreter lock, preventing any performance benefit.



You could move the work into a worker process, but the multiprocessing module isn't the drop-in replacement for threading it likes to pretend to be. It's full of weird copy semantics, unintuitive restrictions, and platform-dependent behavior, as well as just having a lot of communication overhead.



If you've got I/O along with your computation, it's fairly simple to shove the generator's work into its own thread to at least get some work done during the I/O:



from queue import Queue
import threading

def worker(queue, n):
gen = generator()
for i in range(n):
queue.put(next(gen))

def caller():
queue = Queue()
worker_thread = threading.Thread(worker, args=(queue, n))
worker_thread.start()
for i in range(n):
element = queue.get()
another_very_long_computation()





share|improve this answer























  • Actually very_long_computation() is about 50% of computation and 50% I/O. Do you think it is possible to overlap with at least the I/O part?
    – miditower
    Nov 9 at 13:05










  • @miditower: See the edit.
    – user2357112
    Nov 10 at 5:41











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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes








up vote
3
down vote



accepted










There is no simple way, especially since you've got very_long_computation and another_very_long_computation instead of very_slow_io. Even if you moved generator into its own thread, you'd be limited by CPython's global interpreter lock, preventing any performance benefit.



You could move the work into a worker process, but the multiprocessing module isn't the drop-in replacement for threading it likes to pretend to be. It's full of weird copy semantics, unintuitive restrictions, and platform-dependent behavior, as well as just having a lot of communication overhead.



If you've got I/O along with your computation, it's fairly simple to shove the generator's work into its own thread to at least get some work done during the I/O:



from queue import Queue
import threading

def worker(queue, n):
gen = generator()
for i in range(n):
queue.put(next(gen))

def caller():
queue = Queue()
worker_thread = threading.Thread(worker, args=(queue, n))
worker_thread.start()
for i in range(n):
element = queue.get()
another_very_long_computation()





share|improve this answer























  • Actually very_long_computation() is about 50% of computation and 50% I/O. Do you think it is possible to overlap with at least the I/O part?
    – miditower
    Nov 9 at 13:05










  • @miditower: See the edit.
    – user2357112
    Nov 10 at 5:41















up vote
3
down vote



accepted










There is no simple way, especially since you've got very_long_computation and another_very_long_computation instead of very_slow_io. Even if you moved generator into its own thread, you'd be limited by CPython's global interpreter lock, preventing any performance benefit.



You could move the work into a worker process, but the multiprocessing module isn't the drop-in replacement for threading it likes to pretend to be. It's full of weird copy semantics, unintuitive restrictions, and platform-dependent behavior, as well as just having a lot of communication overhead.



If you've got I/O along with your computation, it's fairly simple to shove the generator's work into its own thread to at least get some work done during the I/O:



from queue import Queue
import threading

def worker(queue, n):
gen = generator()
for i in range(n):
queue.put(next(gen))

def caller():
queue = Queue()
worker_thread = threading.Thread(worker, args=(queue, n))
worker_thread.start()
for i in range(n):
element = queue.get()
another_very_long_computation()





share|improve this answer























  • Actually very_long_computation() is about 50% of computation and 50% I/O. Do you think it is possible to overlap with at least the I/O part?
    – miditower
    Nov 9 at 13:05










  • @miditower: See the edit.
    – user2357112
    Nov 10 at 5:41













up vote
3
down vote



accepted







up vote
3
down vote



accepted






There is no simple way, especially since you've got very_long_computation and another_very_long_computation instead of very_slow_io. Even if you moved generator into its own thread, you'd be limited by CPython's global interpreter lock, preventing any performance benefit.



You could move the work into a worker process, but the multiprocessing module isn't the drop-in replacement for threading it likes to pretend to be. It's full of weird copy semantics, unintuitive restrictions, and platform-dependent behavior, as well as just having a lot of communication overhead.



If you've got I/O along with your computation, it's fairly simple to shove the generator's work into its own thread to at least get some work done during the I/O:



from queue import Queue
import threading

def worker(queue, n):
gen = generator()
for i in range(n):
queue.put(next(gen))

def caller():
queue = Queue()
worker_thread = threading.Thread(worker, args=(queue, n))
worker_thread.start()
for i in range(n):
element = queue.get()
another_very_long_computation()





share|improve this answer














There is no simple way, especially since you've got very_long_computation and another_very_long_computation instead of very_slow_io. Even if you moved generator into its own thread, you'd be limited by CPython's global interpreter lock, preventing any performance benefit.



You could move the work into a worker process, but the multiprocessing module isn't the drop-in replacement for threading it likes to pretend to be. It's full of weird copy semantics, unintuitive restrictions, and platform-dependent behavior, as well as just having a lot of communication overhead.



If you've got I/O along with your computation, it's fairly simple to shove the generator's work into its own thread to at least get some work done during the I/O:



from queue import Queue
import threading

def worker(queue, n):
gen = generator()
for i in range(n):
queue.put(next(gen))

def caller():
queue = Queue()
worker_thread = threading.Thread(worker, args=(queue, n))
worker_thread.start()
for i in range(n):
element = queue.get()
another_very_long_computation()






share|improve this answer














share|improve this answer



share|improve this answer








edited Nov 10 at 5:41

























answered Nov 8 at 18:54









user2357112

148k12154242




148k12154242












  • Actually very_long_computation() is about 50% of computation and 50% I/O. Do you think it is possible to overlap with at least the I/O part?
    – miditower
    Nov 9 at 13:05










  • @miditower: See the edit.
    – user2357112
    Nov 10 at 5:41


















  • Actually very_long_computation() is about 50% of computation and 50% I/O. Do you think it is possible to overlap with at least the I/O part?
    – miditower
    Nov 9 at 13:05










  • @miditower: See the edit.
    – user2357112
    Nov 10 at 5:41
















Actually very_long_computation() is about 50% of computation and 50% I/O. Do you think it is possible to overlap with at least the I/O part?
– miditower
Nov 9 at 13:05




Actually very_long_computation() is about 50% of computation and 50% I/O. Do you think it is possible to overlap with at least the I/O part?
– miditower
Nov 9 at 13:05












@miditower: See the edit.
– user2357112
Nov 10 at 5:41




@miditower: See the edit.
– user2357112
Nov 10 at 5:41


















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