faulthandler: don't dump all threads when running without the GIL

It's not safe to access other threads stacks when running without the GIL.

Lib/test/support/script_helper.py

@@ -39,7 +39,7 @@ def interpreter_requires_environment():
  global __cached_interp_requires_environment
  if __cached_interp_requires_environment is None:
  # If PYTHONHOME is set, assume that we need it
- if 'PYTHONHOME' in os.environ:
+ if 'PYTHONHOME' in os.environ or 'PYTHONGIL' in os.environ:
  __cached_interp_requires_environment = True
  return True
  # cannot run subprocess, assume we don't need it

Lib/test/test_capi/test_misc.py

@@ -311,7 +311,7 @@ def test_getitem_with_error(self):
  r'Python runtime state: initialized\n'
  r'ValueError: bug\n'
  r'\n'
- r'Current thread .* \(most recent call first\):\n'
+ r'(Current thread|Stack).* \(most recent call first\):\n'
  r' File .*, line 6 in <module>\n'
  r'\n'
  r'Extension modules: _testcapi \(total: 1\)\n')

Lib/test/test_faulthandler.py

@@ -95,21 +95,25 @@ def check_error(self, code, lineno, fatal_error, *,
 
  Raise an error if the output doesn't match the expected format.
  """
+ if sys.flags.nogil:
+ all_threads = False
  if all_threads:
  if know_current_thread:
  header = 'Current thread 0x[0-9a-f]+'
  else:
  header = 'Thread 0x[0-9a-f]+'
- else:
+ elif know_current_thread:
  header = 'Stack'
  regex = [f'^{fatal_error}']
  if py_fatal_error:
  regex.append("Python runtime state: initialized")
  regex.append('')
- regex.append(fr'{header} \(most recent call first\):')
- if garbage_collecting:
+ if all_threads or know_current_thread:
+ regex.append(fr'{header} \(most recent call first\):')
+ if garbage_collecting and all_threads:
  regex.append(' Garbage-collecting')
- regex.append(fr' File "<string>", line {lineno} in {function}')
+ if all_threads or know_current_thread:
+ regex.append(fr' File "<string>", line {lineno} in {function}')
  regex = '\n'.join(regex)
 
  if other_regex:
@@ -691,6 +695,8 @@ def check_register(self, filename=False, all_threads=False,
 
  Raise an error if the output doesn't match the expected format.
  """
+ if sys.flags.nogil:
+ all_threads = False
  signum = signal.SIGUSR1
  code = """
  import faulthandler

Modules/faulthandler.c

@@ -183,6 +183,11 @@ faulthandler_dump_traceback(int fd, int all_threads,
 
  reentrant = 1;
 
+ if (_PyRuntime.preconfig.disable_gil) {
+ // It's not safe to dump all threads when running without the GIL.
+ all_threads = 0;
+ }
+
  /* SIGSEGV, SIGFPE, SIGABRT, SIGBUS and SIGILL are synchronous signals and
  are thus delivered to the thread that caused the fault. Get the Python
  thread state of the current thread.

Python/pylifecycle.c

@@ -2559,7 +2559,14 @@ _Py_FatalError_DumpTracebacks(int fd, PyInterpreterState *interp,
  PUTS(fd, "\n");
 
  /* display the current Python stack */
- _Py_DumpTracebackThreads(fd, interp, tstate);
+ if (_PyRuntime.preconfig.disable_gil) {
+ if (tstate != NULL) {
+ _Py_DumpTraceback(fd, tstate);
+ }
+ }
+ else {
+ _Py_DumpTracebackThreads(fd, interp, tstate);
+ }
 }
 
 /* Print the current exception (if an exception is set) with its traceback,