Files
zulip/zerver/lib/parallel.py
Anders Kaseorg 365fe0b3d5 python: Sort imports with isort.
Fixes #2665.

Regenerated by tabbott with `lint --fix` after a rebase and change in
parameters.

Note from tabbott: In a few cases, this converts technical debt in the
form of unsorted imports into different technical debt in the form of
our largest files having very long, ugly import sequences at the
start.  I expect this change will increase pressure for us to split
those files, which isn't a bad thing.

Signed-off-by: Anders Kaseorg <anders@zulip.com>
2020-06-11 16:45:32 -07:00

75 lines
2.0 KiB
Python

import errno
import os
import pty
import sys
from typing import Callable, Dict, Iterable, Iterator, Tuple, TypeVar
JobData = TypeVar('JobData')
def run_parallel(job: Callable[[JobData], int],
data: Iterable[JobData],
threads: int=6) -> Iterator[Tuple[int, JobData]]:
pids: Dict[int, JobData] = {}
def wait_for_one() -> Tuple[int, JobData]:
while True:
try:
(pid, status) = os.wait()
return status, pids.pop(pid)
except KeyError:
pass
for item in data:
pid = os.fork()
if pid == 0:
sys.stdin.close()
try:
os.close(pty.STDIN_FILENO)
except OSError as e:
if e.errno != errno.EBADF:
raise
sys.stdin = open("/dev/null")
os._exit(job(item))
pids[pid] = item
threads = threads - 1
if threads == 0:
(status, item) = wait_for_one()
threads += 1
yield (status, item)
if status != 0:
# Stop if any error occurred
break
while True:
try:
(status, item) = wait_for_one()
yield (status, item)
except OSError as e:
if e.errno == errno.ECHILD:
break
else:
raise
if __name__ == "__main__":
# run some unit tests
import time
jobs = [10, 19, 18, 6, 14, 12, 8, 2, 1, 13, 3, 17, 9, 11, 5, 16, 7, 15, 4]
expected_output = [6, 10, 12, 2, 1, 14, 8, 3, 18, 19, 5, 9, 13, 11, 4, 7, 17, 16, 15]
def wait_and_print(x: int) -> int:
time.sleep(x * 0.1)
return 0
output = []
for (status, job) in run_parallel(wait_and_print, jobs):
output.append(job)
if output == expected_output:
print("Successfully passed test!")
else:
print("Failed test!")
print(jobs)
print(expected_output)
print(output)