Added check if thraeding is running before executing start thread.

src/OpenThreads/pthreads/PThread.cpp

@@ -603,6 +603,12 @@ bool Thread::isRunning()
 //
 int Thread::start() {
 
+    PThreadPrivateData *pd = static_cast<PThreadPrivateData *> (_prvData);
+    if (pd->isRunning())
+    {
+        return 0;
+    }
+
     int status;
     pthread_attr_t thread_attr;
 
@@ -612,8 +618,6 @@ int Thread::start() {
         return status;
     }
 
-    PThreadPrivateData *pd = static_cast<PThreadPrivateData *> (_prvData);
-
     //-------------------------------------------------------------------------
     // Set the stack size if requested, but not less than a platform reasonable
     // value.