bpo-37224: Using threading.Event to make sure the thread is running already. by shihai1991 · Pull Request #26598 · python/cpython

test_already_running (test.test__xxsubinterpreters.RunStringTests) ... spam
[InterpreterID(0), InterpreterID(60)]
FAIL

======================================================================
FAIL: test_already_running (test.test__xxsubinterpreters.RunStringTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/shihai/cpython/Lib/test/test__xxsubinterpreters.py", line 836, in test_already_running 
    with self.assertRaises(RuntimeError):
AssertionError: RuntimeError not raised

---------------------------------------------------------------------- 

Ran 123 tests in 111.315s

FAILED (failures=1, skipped=6)
Warning -- Uncaught thread exception: RuntimeError
Exception in thread Thread-8 (run):
Traceback (most recent call last):
  File "/home/shihai/cpython/Lib/threading.py", line 1006, in _bootstrap_inner
    self.run()
  File "/home/shihai/cpython/Lib/threading.py", line 943, in run
    self._target(*self._args, **self._kwargs)
  File "/home/shihai/cpython/Lib/test/test__xxsubinterpreters.py", line 50, in run
    interpreters.run_string(interp, dedent(f"""
RuntimeError: unrecognized interpreter ID 60
test test__xxsubinterpreters failed

diff --git a/Lib/test/test__xxsubinterpreters.py b/Lib/test/test__xxsubinterpreters.py
index 7baea69a4e5..2b2a3d4bd7d 100644
--- a/Lib/test/test__xxsubinterpreters.py
+++ b/Lib/test/test__xxsubinterpreters.py
@@ -42,8 +42,13 @@ def _run_output(interp, request, shared=None):
 @contextlib.contextmanager
 def _running(interp):
     r, w = os.pipe()
+    # [bpo-37224](https://bugs.python.org/issue37224): Using threading.Event to make sure
+    # the interpreter is running already.
+    done = threading.Event()
+    print(interpreters.list_all())
     def run():
         interpreters.run_string(interp, dedent(f"""
+            {done.set()}
             # wait for "signal"
             with open({r}, encoding="utf-8") as rpipe:
                 rpipe.read()
@@ -51,6 +56,7 @@ def run():

     t = threading.Thread(target=run)
     t.start()
+    done.wait()

     yield