Guard LockSupport.unpark with Thread.currentThread() checks for better performance

Author: elizarov

kotlinx-coroutines-core/src/main/kotlin/kotlinx/coroutines/experimental/Builders.kt

@@ -91,7 +91,8 @@ private class BlockingCoroutine<T>(
     init { initParentJob(newContext[Job]) }
 
     override fun afterCompletion(state: Any?) {
-        LockSupport.unpark(blockedThread)
+        if (Thread.currentThread() != blockedThread)
+            LockSupport.unpark(blockedThread)
     }
 
     @Suppress("UNCHECKED_CAST")

kotlinx-coroutines-core/src/main/kotlin/kotlinx/coroutines/experimental/EventLoop.kt

@@ -69,7 +69,8 @@ internal class EventLoopImpl(
         } else
             queue.addLastIf(node) { parentJob!!.isActive }
         if (added) {
-            LockSupport.unpark(thread)
+            if (Thread.currentThread() != thread)
+                LockSupport.unpark(thread)
         } else {
             node.run()
         }