Github user mjsax commented on a diff in the pull request:
https://github.com/apache/flink/pull/750#discussion_r38132263
--- Diff:
flink-runtime/src/main/scala/org/apache/flink/runtime/taskmanager/TaskManager.scala
---
@@ -411,6 +411,23 @@ class TaskManager(
log.debug(s"Cannot find task to fail for execution
${executionID})")
}
+ // stops a task
+ case StopTask(executionID) =>
+ val task = runningTasks.get(executionID)
+ if (task != null) {
+ try {
+ task.stopExecution()
--- End diff --
Well. We know, that stop is only sent to sources, thus, the user function
is of type `SourceFunction`. The `cancel()` method has the following JavaDoc:
```
/**
* Cancels the source. Most sources will have a while loop inside the
* {@link #run} method. You need to ensure that the source will break
out of this loop. This
* can be achieved by having a volatile field "isRunning" that is
checked in the loop and that
* is set to false in this method.
*/
void cancel();
```
I interpreted this a a non-blocking function. Even if this requirement is
not specified explicitly. We could just do this (need to talk to other
streaming folk about implication though). Or we add a new method `stop()` to
`SourceFunction`. However, this implies to change a lot of code... All classes
implementing `SourceFunction` need to get extended (this was another reason why
I just used `cancel()`).
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