Thanks for writing this Andrew! I think you're right, it doesn't really offer a performance advantage over using multiple processes, so I guess I should stick to ProcessPoolExecutor. Thanks for taking the time to write this! Ram. On Tue, Jan 21, 2014 at 9:30 PM, Andrew Barnert wrote:

I slapped together a fork of concurrent/futures/process.py. It's named "procthreadex.py", and it just uses a ThreadPoolExecutor in the _process_worker function. You can get it at http://pastebin.com/Ba2KPYy3, and a test program skeleton at http://pastebin.com/ifwX6NaB.

Maybe you can find a use case where ProcessThreadPoolExecutor(4, 4) outperforms ProcessPoolExecutor(16). (I haven't been able to.)

------------------------------ *From:* Ram Rachum *To:* Andrew Barnert *Cc:* "python-ideas@googlegroups.com" *Sent:* Tuesday, January 21, 2014 2:17 AM

*Subject:* Re: [Python-ideas] Add `n_threads` argument to `concurrent.futures.ProcessPoolExecutor`

If you're writing code that needs to use both a lot of IO and a lot of CPU. For example, you're downloading many items from the internet and then doing post-processing on them.

On Tue, Jan 21, 2014 at 10:42 AM, Andrew Barnert wrote:

On Jan 17, 2014, at 5:00, Ram Rachum wrote:

...

Hi,

I'd like to use `concurrent.futures.ProcessPoolExecutor` but have each process contain multiple worker threads. We could have an `n_threads` argument to the constructor, defaulting to 1 to maintain backward compatibility, and setting a value higher than 1 would cause multiple threads to be spawned in each process.

What for?

Generally you use processes because you can't use threads. Whether this is because you're running CPU-bound code that needs to get around the GIL, because you want complete isolation between tasks, because your platform doesn't support threads, or any other reason I can think of, you wouldn't want threads per process either.

There are use cases for multiple processes of multiple threads, like running four independent IOCP-based servers (let them all try to use all your cores and let the kernel load balance among them), or isolated tasks with sharing-based subtasks... But those kinds of uses don't make sense in a single executor.