From 4fca0447dd8bd0395052825a19fef543d321e60f Mon Sep 17 00:00:00 2001
From: Patrik Nordwall <patrik.nordwall@gmail.com>
Date: Mon, 19 Sep 2016 14:51:36 +0200
Subject: [PATCH] improve shutdown of TaskRunner, #21430

* important that no tasks are run after shutdown
* could be a reason for segfault
---
 .../scala/akka/remote/artery/TaskRunner.scala | 22 ++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/akka-remote/src/main/scala/akka/remote/artery/TaskRunner.scala b/akka-remote/src/main/scala/akka/remote/artery/TaskRunner.scala
index e3f093e0f6..1f6ca158d4 100644
--- a/akka-remote/src/main/scala/akka/remote/artery/TaskRunner.scala
+++ b/akka-remote/src/main/scala/akka/remote/artery/TaskRunner.scala
@@ -63,6 +63,14 @@ private[akka] object TaskRunner {
       tryRemove(0)
     }
 
+    def removeAll(): Unit = {
+      var i = 0
+      while (i < elements.length) {
+        elements(i) = null.asInstanceOf[T]
+        i += 1
+      }
+    }
+
     /**
      * All elements as an array for efficient iteration.
      * The elements can be `null`.
@@ -138,12 +146,14 @@ private[akka] class TaskRunner(system: ExtendedActorSystem, val idleCpuLevel: In
       running = true
       while (running) {
         processCommand(cmdQueue.poll())
-        executeTasks()
-        if (reset) {
-          reset = false
-          idleStrategy.reset()
+        if (running) {
+          executeTasks()
+          if (reset) {
+            reset = false
+            idleStrategy.reset()
+          }
+          idleStrategy.idle()
         }
-        idleStrategy.idle()
       }
     } catch {
       case NonFatal(e) ⇒
@@ -178,6 +188,8 @@ private[akka] class TaskRunner(system: ExtendedActorSystem, val idleCpuLevel: In
       case Remove(task) ⇒ tasks.remove(task)
       case Shutdown ⇒
         running = false
+        tasks.removeAll() // gc friendly
+        while (cmdQueue.poll() != null) () // gc friendly
         shutdown.trySuccess(Done)
     }
   }