Github user chtyim commented on a diff in the pull request:
https://github.com/apache/twill/pull/58#discussion_r132297305
--- Diff:
twill-yarn/src/main/java/org/apache/twill/internal/appmaster/ApplicationMasterService.java
---
@@ -193,7 +200,91 @@ private EventHandler
createEventHandler(TwillSpecification twillSpec) throws Cla
Preconditions.checkArgument(EventHandler.class.isAssignableFrom(handlerClass),
"Class {} does not implements {}",
handlerClass,
EventHandler.class.getName());
- return Instances.newInstance((Class<? extends EventHandler>)
handlerClass);
+ final EventHandler delegate = Instances.newInstance((Class<? extends
EventHandler>) handlerClass);
+ if (delegate == null) {
+ // if no handler is specified, return an EventHandler with no-op
+ return new EventHandler() {};
+ }
+ // wrap the delegate EventHandler so that all errors will be caught
+ return new EventHandler() {
--- End diff --
You'll need to wrap the `initialize` as well. Also, I'd suggest if
`initialize` throw exception, you'll just ignore all calls to other lifecycle
methods to avoid excessive logging.
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