Revert "[3.11] pythongh-94026: Buffer regrtest worker stdout in tempo…

…rary file (pythonGH-94253) (pythonGH-94408)"

This reverts commit 0122ab2.

Lib/test/libregrtest/runtest_mp.py

@@ -5,11 +5,10 @@
 import signal
 import subprocess
 import sys
-import tempfile
 import threading
 import time
 import traceback
-from typing import NamedTuple, NoReturn, Literal, Any, TextIO
+from typing import NamedTuple, NoReturn, Literal, Any
 
 from test import support
 from test.support import os_helper
@@ -52,7 +51,7 @@ def parse_worker_args(worker_args) -> tuple[Namespace, str]:
  return (ns, test_name)
 
 
-def run_test_in_subprocess(testname: str, ns: Namespace, stdout_fh: TextIO) -> subprocess.Popen:
+def run_test_in_subprocess(testname: str, ns: Namespace) -> subprocess.Popen:
  ns_dict = vars(ns)
  worker_args = (ns_dict, testname)
  worker_args = json.dumps(worker_args)
@@ -68,17 +67,18 @@ def run_test_in_subprocess(testname: str, ns: Namespace, stdout_fh: TextIO) -> s
  # Running the child from the same working directory as regrtest's original
  # invocation ensures that TEMPDIR for the child is the same when
  # sysconfig.is_python_build() is true. See issue 15300.
- kw = dict(
- stdout=stdout_fh,
- # bpo-45410: Write stderr into stdout to keep messages order
- stderr=stdout_fh,
- text=True,
- close_fds=(os.name != 'nt'),
- cwd=os_helper.SAVEDCWD,
- )
+ kw = {}
  if USE_PROCESS_GROUP:
  kw['start_new_session'] = True
- return subprocess.Popen(cmd, **kw)
+ return subprocess.Popen(cmd,
+ stdout=subprocess.PIPE,
+ # bpo-45410: Write stderr into stdout to keep
+ # messages order
+ stderr=subprocess.STDOUT,
+ universal_newlines=True,
+ close_fds=(os.name != 'nt'),
+ cwd=os_helper.SAVEDCWD,
+ **kw)
 
 
 def run_tests_worker(ns: Namespace, test_name: str) -> NoReturn:
@@ -204,12 +204,12 @@ def mp_result_error(
  test_result.duration_sec = time.monotonic() - self.start_time
  return MultiprocessResult(test_result, stdout, err_msg)
 
- def _run_process(self, test_name: str, stdout_fh: TextIO) -> int:
+ def _run_process(self, test_name: str) -> tuple[int, str, str]:
  self.start_time = time.monotonic()
 
  self.current_test_name = test_name
  try:
- popen = run_test_in_subprocess(test_name, self.ns, stdout_fh)
+ popen = run_test_in_subprocess(test_name, self.ns)
 
  self._killed = False
  self._popen = popen
@@ -226,10 +226,10 @@ def _run_process(self, test_name: str, stdout_fh: TextIO) -> int:
  raise ExitThread
 
  try:
- # gh-94026: stdout+stderr are written to tempfile
- retcode = popen.wait(timeout=self.timeout)
+ # bpo-45410: stderr is written into stdout
+ stdout, _ = popen.communicate(timeout=self.timeout)
+ retcode = popen.returncode
  assert retcode is not None
- return retcode
  except subprocess.TimeoutExpired:
  if self._stopped:
  # kill() has been called: communicate() fails on reading
@@ -244,12 +244,17 @@ def _run_process(self, test_name: str, stdout_fh: TextIO) -> int:
  # bpo-38207: Don't attempt to call communicate() again: on it
  # can hang until all child processes using stdout
  # pipes completes.
+ stdout = ''
  except OSError:
  if self._stopped:
  # kill() has been called: communicate() fails
  # on reading closed stdout
  raise ExitThread
  raise
+ else:
+ stdout = stdout.strip()
+
+ return (retcode, stdout)
  except:
  self._kill()
  raise
@@ -259,17 +264,7 @@ def _run_process(self, test_name: str, stdout_fh: TextIO) -> int:
  self.current_test_name = None
 
  def _runtest(self, test_name: str) -> MultiprocessResult:
- # gh-94026: Write stdout+stderr to a tempfile as workaround for
- # non-blocking pipes on Emscripten with NodeJS.
- with tempfile.TemporaryFile(
- 'w+', encoding=sys.stdout.encoding
- ) as stdout_fh:
- # gh-93353: Check for leaked temporary files in the parent process,
- # since the deletion of temporary files can happen late during
- # Python finalization: too late for libregrtest.
- retcode = self._run_process(test_name, stdout_fh)
- stdout_fh.seek(0)
- stdout = stdout_fh.read().strip()
+ retcode, stdout = self._run_process(test_name)
 
  if retcode is None:
  return self.mp_result_error(Timeout(test_name), stdout)
@@ -316,6 +311,9 @@ def run(self) -> None:
  def _wait_completed(self) -> None:
  popen = self._popen
 
+ # stdout must be closed to ensure that communicate() does not hang
+ popen.stdout.close()
+
  try:
  popen.wait(JOIN_TIMEOUT)
  except (subprocess.TimeoutExpired, OSError) as exc: