Github user poornachandra commented on a diff in the pull request:
https://github.com/apache/twill/pull/2#discussion_r75439711
--- Diff:
twill-core/src/main/java/org/apache/twill/internal/TwillContainerLauncher.java
---
@@ -153,21 +155,29 @@ public TwillContainerController start(RunId runId,
int instanceId, Class<?> main
.addCommand(firstCommand, command.toArray(new
String[command.size()]))
.launch();
- TwillContainerControllerImpl controller = new
TwillContainerControllerImpl(zkClient, runId, processController);
+ TwillContainerControllerImpl controller =
+ new TwillContainerControllerImpl(zkClient, runId,
runtimeSpec.getName(), instanceId, processController);
controller.start();
return controller;
}
private static final class TwillContainerControllerImpl extends
AbstractZKServiceController
implements
TwillContainerController {
+ private final String runnable;
+ private final int instanceId;
private final ProcessController<Void> processController;
+ // This latch can be used to wait for container shutdown
+ private final CountDownLatch shutdownLatch;
private volatile ContainerLiveNodeData liveData;
- protected TwillContainerControllerImpl(ZKClient zkClient, RunId runId,
+ protected TwillContainerControllerImpl(ZKClient zkClient, RunId runId,
String runnable, int instanceId,
ProcessController<Void>
processController) {
super(runId, zkClient);
+ this.runnable = runnable;
+ this.instanceId = instanceId;
this.processController = processController;
+ this.shutdownLatch = new CountDownLatch(1);
--- End diff --
The thread that stops the container needs to wait until the container
stops. The only good way to know whether the container has stopped or not is to
get a notification from RM during the heartbeat (that happens in a separate
thread). Hence we wait on a `CountDownLatch` until the heartbeat thread calls
`completed()` method where the latch get count down.
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