Chris Riccomini created SAMZA-437:
-------------------------------------
Summary: Remove TaskLifecycleListener
Key: SAMZA-437
URL: https://issues.apache.org/jira/browse/SAMZA-437
Project: Samza
Issue Type: Bug
Components: container
Reporter: Chris Riccomini
We recently had a use case where we needed to wrap the Samza process() method
in some code. The TaskLifecycleListener was insufficient to do this. We get a
beforeProcess and afterProcess, but what we really wanted was:
{code}
def wrapProcess(...) {
foo.doSomething(new Wrapper() {
task.process(...)
})
}
{code}
We ended up just writing a wrapper task, and having the normal code defined via
a subtask config:
{noformat}
task.class=foo.bar.WrapperTask
task.subtask.class=foo.bar.NormalTask
{noformat}
Both of these tasks implement StreamTask. Samza just sees WrapperTask, and
treats it like a normal task. Wrapper task instantiates the subtask, and
manages its lifecycle internally.
This approach seems superior to the TaskLifecycleListener.
* Allows tasks to be composed multiple times.
* Removes this complexity from the Samza framework, and makes it a concern of
the job owner.
* Allows the wrapper task to do things like filtering messages, tweaking
configs and serialization, catching exceptions, etc.
Given this, it seems that TaskLifecycleListener is a degenerate case, and adds
complexity to the framework. I propose removing it.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
