Threading in Python
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Threading in Python
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Re: Threading in Python
#2Where does the GIL factor into this? I thought using threads in Python gives basically no gains unless all the heavy work is being done outside the interpreter. I've always gone with the multiprocessing module instead.
Re: Threading in Python
#3Where does the GIL factor into this? I thought using threads in Python gives basically no gains unless all the heavy work is being done outside the interpreter. I've always gone with the multiprocessing module instead.
Python threads are only useful if you use C modules that handle the GIL correctly and I/O bound stuff from the standard library, it gives no speed boost for python code
Re: Threading in Python
#4Where does the GIL factor into this? I thought using threads in Python gives basically no gains unless all the heavy work is being done outside the interpreter. I've always gone with the multiprocessing module instead.
This stems back to parallelism vs. concurrency. Yes, it is true that your Python threads will not run in parallel but they will run concurrently. If you're curious about parallelism vs. concurrency, here is a great talk by Rob Pike on the subject: http://vimeo.com/49718712
Re: Threading in Python
#5Where does the GIL factor into this? I thought using threads in Python gives basically no gains unless all the heavy work is being done outside the interpreter. I've always gone with the multiprocessing module instead.
Python threads are only useful if you use C modules that handle the GIL correctly and I/O bound stuff from the standard library, it gives no speed boost for python code
If not for performance, why would anybody use it? Scalability?
Re: Threading in Python
#6Where does the GIL factor into this? I thought using threads in Python gives basically no gains unless all the heavy work is being done outside the interpreter. I've always gone with the multiprocessing module instead.
Python threads are only useful if you use C modules that handle the GIL correctly and I/O bound stuff from the standard library, it gives no speed boost for python code
here's one more usecase which is probably very common: When you use python as glue to call other programs which can run asynchronously. As an example I've used python once to implement a parallelized genetic algorithm where the evaluation function was a matlab program. It was quite a breeze to spawn hundreds of such threads over ssh using one PC as the controller - if only I hadn't shocked the local sysadmins ;-).
Re: Threading in Python
#7Earlier quoted context omitted.
Python threads are only useful if you use C modules that handle the GIL correctly and I/O bound stuff from the standard library, it gives no speed boost for python code
If not for performance, why would anybody use it? Scalability?
I/O bound stuff from the standard library
still for performance
Re: Threading in Python
#8Earlier quoted context omitted.
Python threads are only useful if you use C modules that handle the GIL correctly and I/O bound stuff from the standard library, it gives no speed boost for python code
If not for performance, why would anybody use it? Scalability?
It still provides concurrency.
Re: Threading in Python
#9Re: Threading in Python
#10Some developers, when confronted with a problem, think
"I know, I'll use threads"
have two Now problems they.