Python Flask sending response immediately

Question

I need to execute Process during request like below

@app.route('/test')
def test_process():
    print "starting new process"
    p = Process(target=do_long_extra_job)
    p.start()

    return "this is response"

do_long_extra_job is on another process, so expected work flow is like this

1. start a process
2. response
3. long running extra job finished

but actual flow is like this

1. stat a process
2. long running extra job finished
3. response

how can I response immediately after starting new process?

Answer 1

The apply_async method in the multiprocessing.Pool class may work for you. 'Process' won't work for you in this case since it's a blocking method, meaning that your return statement will not execute until p.start() has finished executing.

Example with apply_async and multiprocessing.Pool:

def do_long_extra_job():
    #some extra long process
    return

@app.route('/test')
def test_process():
    print "starting new process"
    pool = multiprocessing.Pool(processes=1)
    pool.apply_async(do_long_extra_job)
    return "this is response"