GH-110829: Ensure Thread.join() joins the OS thread (#110848)

Joining a thread now ensures the underlying OS thread has exited. This is required for safer fork() in multi-threaded processes.

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Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/Python/thread_pthread_stubs.h b/Python/thread_pthread_stubs.h
index 48bad36ec44..4741e594e52 100644
--- a/Python/thread_pthread_stubs.h
+++ b/Python/thread_pthread_stubs.h
@@ -94,6 +94,15 @@ pthread_detach(pthread_t thread)
     return 0;
 }
 
+int
+pthread_join(pthread_t thread, void** value_ptr)
+{
+    if (value_ptr) {
+        *value_ptr = NULL;
+    }
+    return 0;
+}
+
 PyAPI_FUNC(pthread_t) pthread_self(void)
 {
     return 0;