The function foo
below returns a string 'foo'
. How can I get the value 'foo'
which is returned from the thread’s target?
from threading import Thread def foo(bar): print('hello {}'.format(bar)) return 'foo' thread = Thread(target=foo, args=('world!',)) thread.start() return_value = thread.join()
The “one obvious way to do it”, shown above, doesn’t work: thread.join()
returned None
.
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Answer
In Python 3.2+, stdlib concurrent.futures
module provides a higher level API to threading
, including passing return values or exceptions from a worker thread back to the main thread:
import concurrent.futures def foo(bar): print('hello {}'.format(bar)) return 'foo' with concurrent.futures.ThreadPoolExecutor() as executor: future = executor.submit(foo, 'world!') return_value = future.result() print(return_value)