Fix for issue 25236

runtime/vm/os_thread.h

Index: runtime/vm/os_thread.h
diff --git a/runtime/vm/os_thread.h b/runtime/vm/os_thread.h
index 9371b4538ae3d44227f23d13f58ac3bcd182551e..2dbbb510deda636621ef52c47cc6b278666e7841 100644
--- a/runtime/vm/os_thread.h
+++ b/runtime/vm/os_thread.h
@@ -50,7 +50,6 @@ class BaseThread {
 // Low-level operations on OS platform threads.
 class OSThread : public BaseThread {
  public:
-  OSThread();
   ~OSThread();
 
   ThreadId id() const {
@@ -170,17 +169,26 @@ class OSThread : public BaseThread {
   static bool Compare(ThreadId a, ThreadId b);
   static void GetThreadCpuUsage(ThreadId thread_id, int64_t* cpu_usage);
 
+  static OSThread* CreateOSThread();

[zra, 2015/12/17 16:37:59]

Maybe this should go up at the top of the class where the constructor would
normally go to make it easier to find. Add a comment explaining when NULL can be
returned.

[siva, 2015/12/17 18:19:13]

Done.

+
   // Called at VM startup and shutdown.
   static void InitOnce();
 
   static bool IsThreadInList(ThreadJoinId join_id);
 
+  static void DisableOSThreadCreation();
+  static void EnableOSThreadCreation();
+
   static const intptr_t kStackSizeBuffer = (4 * KB * kWordSize);
 
   static const ThreadId kInvalidThreadId;
   static const ThreadJoinId kInvalidThreadJoinId;
 
  private:
+  // The constructor is private as CreateOSThread should be used
+  // to create a new OSThread structure.
+  OSThread();
+
   // These methods should not be used in a generic way and hence
   // are private, they have been added to solve the problem of
   // accessing the VM thread structure from an OSThread object
@@ -220,6 +228,7 @@ class OSThread : public BaseThread {
 
   static OSThread* thread_list_head_;
   static Mutex* thread_list_lock_;
+  static bool creation_enabled_;
 
   friend class OSThreadIterator;
   friend class ThreadInterrupterWin;