From 1858233ffaee482a73a91b796f02ebb7ae1306b9 Mon Sep 17 00:00:00 2001
From: Peter Zhu <peter@peterzhu.ca>
Date: Fri, 3 Oct 2025 19:51:01 -0400
Subject: [PATCH] Free the native thread of the main thread on FREE_AT_EXIT

---
 internal/thread.h | 2 ++
 thread.c          | 9 +++++++++
 vm.c              | 3 +--
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/internal/thread.h b/internal/thread.h
index 928126c3b0..21efeeebc0 100644
--- a/internal/thread.h
+++ b/internal/thread.h
@@ -64,6 +64,8 @@ void rb_thread_io_close_wait(struct rb_io *);
 
 void rb_ec_check_ints(struct rb_execution_context_struct *ec);
 
+void rb_thread_free_native_thread(void *th_ptr);
+
 RUBY_SYMBOL_EXPORT_BEGIN
 
 void *rb_thread_prevent_fork(void *(*func)(void *), void *data); /* for ext/socket/raddrinfo.c */
diff --git a/thread.c b/thread.c
index 5556100102..0419fdf054 100644
--- a/thread.c
+++ b/thread.c
@@ -529,6 +529,15 @@ thread_cleanup_func(void *th_ptr, int atfork)
     rb_native_mutex_destroy(&th->interrupt_lock);
 }
 
+void
+rb_thread_free_native_thread(void *th_ptr)
+{
+    rb_thread_t *th = th_ptr;
+
+    native_thread_destroy_atfork(th->nt);
+    th->nt = NULL;
+}
+
 static VALUE rb_threadptr_raise(rb_thread_t *, int, VALUE *);
 static VALUE rb_thread_to_s(VALUE thread);
 
diff --git a/vm.c b/vm.c
index 8bdf9e4fc2..c9bf3dce36 100644
--- a/vm.c
+++ b/vm.c
@@ -3306,8 +3306,7 @@ ruby_vm_destruct(rb_vm_t *vm)
             rb_id_table_free(vm->constant_cache);
             set_free_table(vm->unused_block_warning_table);
 
-            xfree(th->nt);
-            th->nt = NULL;
+            rb_thread_free_native_thread(th);
 
 #ifndef HAVE_SETPROCTITLE
             ruby_free_proctitle();