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threading.Thread: Add start=False parameter to start immediately the thread #155334
Description
It's common to create multiple threads, start them, and then join them. Example:
threads = [
threading.Thread(target=run_a),
threading.Thread(target=run_b),
]
for thread in threads:
thread.start()
...
for thread in threads:
thread.join()I propose adding a start=False parameter to threading.Thread to start immediately the thread. The example would become:
threads = [
threading.Thread(target=run_a, start=True),
threading.Thread(target=run_b, start=True),
]
...
for thread in threads:
thread.join()The new parameter would solve the old issue gh-93293 which requests to return self in start(). The issue example:
threads = []
for i in range(10):
thread = threading.Thread(target=fn, args=(i,))
thread.start()
threads.append(thread)
for t in threads:
t.join()would become:
threads = [threading.Thread(target=fn, args=(i,), start=True) for i in range(10)]
for t in threads:
t.join()
Activity
vstinner commentedon Aug 7, 2026
Adding a start parameter was mentioned in https://discuss.python.org/t/add-a-threading-run-convenience-function/108430 discussion.
ZeroIntensity commentedon Aug 9, 2026
I think
threading.run/threading.run_daemonwould be better, because the ergonomics ofgroup(see #155348),args, andkwargsare bad. Constructors should also generally not perform expensive operations.