https://github.com/python/cpython/commit/847c803c13093f3ec0a09188831e1a44f27894b1 commit: 847c803c13093f3ec0a09188831e1a44f27894b1 branch: 3.12 author: Miss Islington (bot) <[email protected]> committer: colesbury <[email protected]> date: 2024-07-10T14:54:45Z summary:
[3.12] gh-107851: Fix spurious failures in fcntl eintr tests (GH-121556) (#121586) On heavily loaded machines, the subprocess may finish its sleep before the parent process manages to synchronize with it via a failed lock. This leads to errors like: Exception: failed to sync child in 300.3 sec Use pipes instead to mutually synchronize between parent and child. (cherry picked from commit af9f6de6ea930b607f948f2c91a87fe4ca9d64db) Co-authored-by: Sam Gross <[email protected]> files: M Lib/test/_test_eintr.py diff --git a/Lib/test/_test_eintr.py b/Lib/test/_test_eintr.py index 15586f15dfab30..493932d6c6d441 100644 --- a/Lib/test/_test_eintr.py +++ b/Lib/test/_test_eintr.py @@ -18,6 +18,7 @@ import socket import subprocess import sys +import textwrap import time import unittest @@ -492,29 +493,31 @@ def test_devpoll(self): self.check_elapsed_time(dt) -class FNTLEINTRTest(EINTRBaseTest): +class FCNTLEINTRTest(EINTRBaseTest): def _lock(self, lock_func, lock_name): self.addCleanup(os_helper.unlink, os_helper.TESTFN) - code = '\n'.join(( - "import fcntl, time", - "with open('%s', 'wb') as f:" % os_helper.TESTFN, - " fcntl.%s(f, fcntl.LOCK_EX)" % lock_name, - " time.sleep(%s)" % self.sleep_time)) - start_time = time.monotonic() - proc = self.subprocess(code) + rd1, wr1 = os.pipe() + rd2, wr2 = os.pipe() + for fd in (rd1, wr1, rd2, wr2): + self.addCleanup(os.close, fd) + code = textwrap.dedent(f""" + import fcntl, os, time + with open('{os_helper.TESTFN}', 'wb') as f: + fcntl.{lock_name}(f, fcntl.LOCK_EX) + os.write({wr1}, b"ok") + _ = os.read({rd2}, 2) # wait for parent process + time.sleep({self.sleep_time}) + """) + proc = self.subprocess(code, pass_fds=[wr1, rd2]) with kill_on_error(proc): with open(os_helper.TESTFN, 'wb') as f: # synchronize the subprocess + ok = os.read(rd1, 2) + self.assertEqual(ok, b"ok") + + # notify the child that the parent is ready start_time = time.monotonic() - for _ in support.sleeping_retry(support.LONG_TIMEOUT, error=False): - try: - lock_func(f, fcntl.LOCK_EX | fcntl.LOCK_NB) - lock_func(f, fcntl.LOCK_UN) - except BlockingIOError: - break - else: - dt = time.monotonic() - start_time - raise Exception("failed to sync child in %.1f sec" % dt) + os.write(wr2, b"go") # the child locked the file just a moment ago for 'sleep_time' seconds # that means that the lock below will block for 'sleep_time' minus some _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3/lists/python-checkins.python.org/ Member address: [email protected]
