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https://issues.apache.org/jira/browse/YARN-4665?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Naganarasimha G R reassigned YARN-4665:
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Assignee: Naganarasimha G R (was: Daniel Templeton)
> Asynch submit can lose application submissions
> ----------------------------------------------
>
> Key: YARN-4665
> URL: https://issues.apache.org/jira/browse/YARN-4665
> Project: Hadoop YARN
> Issue Type: Bug
> Affects Versions: 2.1.0-beta
> Reporter: Daniel Templeton
> Assignee: Naganarasimha G R
>
> The change introduced in YARN-514 opens up a hole into which applications can
> fall and be lost. Prior to YARN-514, the {{submitApplication()}} call did
> not complete until the application state was persisted to the state store.
> After YARN-514, the {{submitApplication()}} call is asynchronous, with the
> application state being saved later.
> If the state store is slow or unresponsive, it may be that an application's
> state may not be persisted for quite a while. During that time, if the RM
> fails (over), all applications that have not yet been persisted to the state
> store will be lost. If the active RM loses ZK connectivity, a significant
> number of job submissions can pile up before the ZK connection times out,
> resulting in a large pile of client failures when it finally does.
> This issue is inherent in the design of YARN-514. I see three solutions:
> 1. Add a WAL to the state store. HBase does it, so we know how to do it. It
> seems like a heavy solution to the original problem, however. It's certainly
> not a trivial change.
> 2. Revert YARN-514 and update the RPC layer to allow a connection to be
> parked if it's doing something that may take a while. This is a generally
> useful feature but could be a deep rabbit hole.
> 3. Revert YARN-514 and add back-pressure to the job submission. For example,
> we set a maximum number of threads that can simultaneously be assigned to
> handle job submissions. When that threshold is reached, new job submissions
> get a try-again-later response. This is also a generally useful feature and
> should be a fairly constrained set of changes.
> I think the third option is the most approachable. It's the smallest change,
> and it adds useful behavior beyond solving the original issue.
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