Fixes for OSThread creation shutdown race.

runtime/vm/os_thread.cc

Index: runtime/vm/os_thread.cc
diff --git a/runtime/vm/os_thread.cc b/runtime/vm/os_thread.cc
index f6a7498280a6a2545b49266a08391066d99aced8..5b2d6e34d1310e0a80ef1fa41163077bc52f3591 100644
--- a/runtime/vm/os_thread.cc
+++ b/runtime/vm/os_thread.cc
@@ -36,18 +36,13 @@ OSThread::OSThread() :
 
 
 OSThread* OSThread::CreateOSThread() {
-  if (thread_list_lock_ == NULL) {
+  MutexLocker ml(thread_list_lock_);
+  if (!creation_enabled_) {
     return NULL;
   }
-  {
-    MutexLocker ml(thread_list_lock_);
-    if (!creation_enabled_) {
-      return NULL;
-    }
-    OSThread* os_thread = new OSThread();
-    AddThreadToListLocked(os_thread);
-    return os_thread;
-  }
+  OSThread* os_thread = new OSThread();
+  AddThreadToListLocked(os_thread);
+  return os_thread;
 }
 
 
@@ -121,15 +116,18 @@ void OSThread::InitOnce() {
 
 void OSThread::Cleanup() {
   if (thread_list_lock_ != NULL) {
+    // We cannot delete the key, yet. See the note about thread_list_lock_.
     // Delete the thread local key.
-    ASSERT(thread_key_ != kUnsetThreadLocalKey);
-    DeleteThreadLocal(thread_key_);
-    thread_key_ = kUnsetThreadLocalKey;
+    // ASSERT(thread_key_ != kUnsetThreadLocalKey);
+    // DeleteThreadLocal(thread_key_);
+    // thread_key_ = kUnsetThreadLocalKey;
 
+    // The thread_list_lock_ cannot be deleted without a bit more cleverness.
+    // See the note in os_thread.h.
     // Delete the global OSThread lock.
-    ASSERT(thread_list_lock_ != NULL);
-    delete thread_list_lock_;
-    thread_list_lock_ = NULL;
+    // ASSERT(thread_list_lock_ != NULL);
+    // delete thread_list_lock_;
+    // thread_list_lock_ = NULL;
   }

[siva, 2016/01/04 23:07:55]

Since everything inside the 'if statement' is commented out why not put the
whole statement under #if 0....#endif

[zra, 2016/01/04 23:21:53]

Done.

 }