Backport fixes to as_completed and map iterators (bpo-27144) #66
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Contributor
Author
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@agronholm As you mentioned you are busy, here you have a reproducer with output from runs before and after the changes in this PR. Note how the count (and obviously memory footprint) of Reproducer script: # file: reproducer.py
import gc
import time
from pympler import summary
from pympler import muppy
from concurrent.futures import ThreadPoolExecutor, as_completed
def random_data(*args):
time.sleep(1)
return bytearray(1024*1024*2)
def gen_executor0():
with ThreadPoolExecutor(1) as executor:
futures = [executor.submit(random_data) for x in range(5)]
for future in as_completed(futures):
futures.remove(future)
future = None
yield
def gen_executor1():
with ThreadPoolExecutor(1) as executor:
for y in executor.map(random_data, range(5)):
y = None
yield
def main(gen_executor):
for cycle in gen_executor():
gc.collect()
summary.print_(summary.summarize(muppy.get_objects()), limit=4)
if __name__ == '__main__':
print("as_completed()")
main(gen_executor0)
print("executor.map()")
main(gen_executor1)Run before this PR: $ python reproducer.py
as_completed()
types | # objects | total size
=========== | =========== | ============
bytearray | 1 | 2.00 MB
dict | 767 | 1.14 MB
str | 8468 | 803.97 KB
code | 2595 | 324.38 KB
types | # objects | total size
=========== | =========== | ============
bytearray | 2 | 4.00 MB
dict | 768 | 1.14 MB
str | 8468 | 803.97 KB
code | 2595 | 324.38 KB
types | # objects | total size
=========== | =========== | ============
bytearray | 3 | 6.00 MB
dict | 767 | 1.14 MB
str | 8468 | 803.97 KB
code | 2595 | 324.38 KB
types | # objects | total size
=========== | =========== | ============
bytearray | 4 | 8.00 MB
dict | 766 | 1.14 MB
str | 8468 | 803.97 KB
code | 2595 | 324.38 KB
types | # objects | total size
=========== | =========== | ============
bytearray | 5 | 10.00 MB
dict | 765 | 1.14 MB
str | 8466 | 803.89 KB
code | 2595 | 324.38 KB
executor.map()
types | # objects | total size
=========== | =========== | ============
bytearray | 1 | 2.00 MB
dict | 766 | 1.14 MB
str | 8465 | 803.84 KB
code | 2596 | 324.50 KB
types | # objects | total size
=========== | =========== | ============
bytearray | 2 | 4.00 MB
dict | 765 | 1.14 MB
str | 8465 | 803.84 KB
code | 2596 | 324.50 KB
types | # objects | total size
=========== | =========== | ============
bytearray | 3 | 6.00 MB
dict | 764 | 1.14 MB
str | 8465 | 803.84 KB
code | 2596 | 324.50 KB
types | # objects | total size
=========== | =========== | ============
bytearray | 4 | 8.00 MB
dict | 763 | 1.14 MB
str | 8465 | 803.84 KB
code | 2596 | 324.50 KB
types | # objects | total size
=========== | =========== | ============
bytearray | 5 | 10.00 MB
dict | 762 | 1.14 MB
str | 8463 | 803.76 KB
code | 2596 | 324.50 KBRun after this PR: $ python reproducer.py
as_completed()
types | # objects | total size
======= | =========== | ============
dict | 765 | 1.14 MB
str | 8470 | 804.44 KB
code | 2596 | 324.50 KB
type | 167 | 148.64 KB
types | # objects | total size
======= | =========== | ============
dict | 764 | 1.14 MB
str | 8470 | 804.44 KB
code | 2596 | 324.50 KB
type | 167 | 148.64 KB
types | # objects | total size
======= | =========== | ============
dict | 761 | 1.14 MB
str | 8470 | 804.44 KB
code | 2596 | 324.50 KB
type | 167 | 148.64 KB
types | # objects | total size
======= | =========== | ============
dict | 758 | 1.13 MB
str | 8470 | 804.44 KB
code | 2596 | 324.50 KB
type | 167 | 148.64 KB
types | # objects | total size
======= | =========== | ============
dict | 755 | 1.13 MB
str | 8461 | 804.04 KB
code | 2596 | 324.50 KB
type | 167 | 148.64 KB
executor.map()
types | # objects | total size
======= | =========== | ============
dict | 764 | 1.14 MB
str | 8467 | 804.30 KB
code | 2597 | 324.62 KB
type | 167 | 148.64 KB
types | # objects | total size
======= | =========== | ============
dict | 761 | 1.14 MB
str | 8467 | 804.30 KB
code | 2597 | 324.62 KB
type | 167 | 148.64 KB
types | # objects | total size
======= | =========== | ============
dict | 758 | 1.13 MB
str | 8467 | 804.30 KB
code | 2597 | 324.62 KB
type | 167 | 148.64 KB
types | # objects | total size
======= | =========== | ============
dict | 755 | 1.13 MB
str | 8467 | 804.30 KB
code | 2597 | 324.62 KB
type | 167 | 148.64 KB
types | # objects | total size
======= | =========== | ============
dict | 752 | 1.13 MB
str | 8458 | 803.91 KB
code | 2597 | 324.62 KB
type | 167 | 148.64 KB |
agronholm
reviewed
Nov 29, 2017
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agronholm
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Two oddities, otherwise looks good.
| yield future | ||
| for f in _yield_finished_futures(finished, waiter, | ||
| ref_collect=(fs,)): | ||
| f = [f] |
Owner
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Why this? Why not just yield f?
Owner
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Ahhh...because otherwise the future would still be referenced by the generator. Gotcha.
Contributor
Author
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Indeed. Maybe Python 4 will consider fixing iteration target vars leaking to the scope :-).
| finished.reverse() | ||
| for f in _yield_finished_futures(finished, waiter, | ||
| ref_collect=(fs, pending)): | ||
| f = [f] |
Owner
|
Thank you very much! |
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Python issues:
concurrent.futures.as_completed()python/cpython#3830