[
https://issues.apache.org/jira/browse/HDFS-895?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12932189#action_12932189
]
Todd Lipcon commented on HDFS-895:
----------------------------------
Yes, we should get this into 20-append for HBase. Right now there seems to be
an issue with the HDFS-724 patch in 20-append, and since these touch very
similar areas of the write pipeline, I want to either temporarily revert 724
from 20-append, or figure out what's wrong with it. No sense adding another
variable into the mix when our current branch has some problems.
> Allow hflush/sync to occur in parallel with new writes to the file
> ------------------------------------------------------------------
>
> Key: HDFS-895
> URL: https://issues.apache.org/jira/browse/HDFS-895
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs client
> Affects Versions: 0.22.0
> Reporter: dhruba borthakur
> Assignee: Todd Lipcon
> Fix For: 0.22.0
>
> Attachments: 895-delta-for-review.txt, hdfs-895-0.20-append.txt,
> hdfs-895-20.txt, hdfs-895-branch-20-append.txt, hdfs-895-ontopof-1497.txt,
> hdfs-895-review.txt, hdfs-895-trunk.txt, hdfs-895.txt, hdfs-895.txt,
> hdfs-895.txt, hdfs-895.txt, hdfs-895.txt, hdfs-895.txt, hdfs-895.txt
>
>
> In the current trunk, the HDFS client methods writeChunk() and hflush./sync
> are syncronized. This means that if a hflush/sync is in progress, an
> applicationn cannot write data to the HDFS client buffer. This reduces the
> write throughput of the transaction log in HBase.
> The hflush/sync should allow new writes to happen to the HDFS client even
> when a hflush/sync is in progress. It can record the seqno of the message for
> which it should receice the ack, indicate to the DataStream thread to star
> flushing those messages, exit the synchronized section and just wai for that
> ack to arrive.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
