thread_sync.c: avoid reaching across stacks of dead threads

rb_ensure is insufficient cleanup for fork and we must
reinitialize all waitqueues in the child process.

Unfortunately this increases the footprint of ConditionVariable,
Queue and SizedQueue by 8 bytes on 32-bit (16 bytes on 64-bit).

[ruby-core:86316] [Bug #14634]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62934 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 2 insertions, 0 deletions

diff --git a/thread.c b/thread.c
index ea0f526d2e..1caea4976c 100644
--- a/thread.c
+++ b/thread.c
@@ -4216,6 +4216,8 @@ rb_thread_atfork_internal(rb_thread_t *th, void (*atfork)(rb_thread_t *, const r
     }
     rb_vm_living_threads_init(vm);
     rb_vm_living_threads_insert(vm, th);
+    rb_thread_sync_reset_all();
+
     vm->sleeper = 0;
     clear_coverage();
 }