bpo-34651: Only allow the main interpreter to fork. (gh-9279)

When os.fork() is called (on platforms that support it) all threads but the current one are destroyed in the child process. Consequently we must ensure that all but the associated interpreter are likewise destroyed. The main interpreter is critical for runtime operation, so we must ensure that fork only happens in the main interpreter.

https://bugs.python.org/issue34651

1 files changed, 3 insertions, 14 deletions

diff --git a/Lib/test/test__xxsubinterpreters.py b/Lib/test/test__xxsubinterpreters.py
index ac76cc1..26032d6 100644
--- a/Lib/test/test__xxsubinterpreters.py
+++ b/Lib/test/test__xxsubinterpreters.py
@@ -824,23 +824,12 @@ class RunStringTests(TestBase):
 
             expected = 'spam spam spam spam spam'
             script = dedent(f"""
-                # (inspired by Lib/test/test_fork.py)
                 import os
-                pid = os.fork()
-                if pid == 0:  # child
+                try:
+                    os.fork()
+                except RuntimeError:
                     with open('{file.name}', 'w') as out:
                         out.write('{expected}')
-                    # Kill the unittest runner in the child process.
-                    os._exit(1)
-                else:
-                    SHORT_SLEEP = 0.1
-                    import time
-                    for _ in range(10):
-                        spid, status = os.waitpid(pid, os.WNOHANG)
-                        if spid == pid:
-                            break
-                        time.sleep(SHORT_SLEEP)
-                    assert(spid == pid)
                 """)
             interpreters.run_string(self.id, script)