GitHub user arunmahadevan opened a pull request:
https://github.com/apache/storm/pull/644
[STORM-837] Support for exactly once semantics in HdfsState
Changes to support exactly once semantics in HdfsState.
1. Moved the file rotation and sync to commit()
2. In pre-commit, if we have previously seen the txnid, recover the data up
to that point by copying to a new file and discard the current data file.
3. In pre-commit atomically update [current txid, the datafile path and the
current offset] in a (per partition) index file.
4. To keep it simple, automatically turn off exactly once semantics if
TimedRotation policy is in use.
Have tested with the normal flow and simulating the recovery scenario, with
both regular Hdfs file and sequence files. Appears to work fine.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/arunmahadevan/storm master
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/storm/pull/644.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #644
----
commit 5631b9d4746f34127a1bc89cb4488d2b2d8ec9d7
Author: Arun Mahadevan <[email protected]>
Date: 2015-07-21T19:04:09Z
Support for exactly once semantics in HdfsState
----
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
