Daryn Sharp created HDFS-7964:
---------------------------------
Summary: Add support for async edit logging
Key: HDFS-7964
URL: https://issues.apache.org/jira/browse/HDFS-7964
Project: Hadoop HDFS
Issue Type: Sub-task
Components: namenode
Affects Versions: 2.0.2-alpha
Reporter: Daryn Sharp
Assignee: Daryn Sharp
Edit logging is a major source of contention within the NN. LogEdit is called
within the namespace write log, while logSync is called outside of the lock to
allow greater concurrency. The handler thread remains busy until logSync
returns to provide the client with a durability guarantee for the response.
Write heavy RPC load and/or slow IO causes handlers to stall in logSync.
Although the write lock is not held, readers are limited/starved and the call
queue fills. Combining an edit log thread with postponed RPC responses from
HADOOP-9953 will provide the same durability guarantee but immediately free up
the handlers.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
