[ https://issues.apache.org/jira/browse/MAPREDUCE-2349?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Siddharth Seth reassigned MAPREDUCE-2349: ----------------------------------------- Assignee: Siddharth Seth > speed up list[located]status calls from input formats > ----------------------------------------------------- > > Key: MAPREDUCE-2349 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-2349 > Project: Hadoop Map/Reduce > Issue Type: Improvement > Components: task > Reporter: Joydeep Sen Sarma > Assignee: Siddharth Seth > Attachments: MAPREDUCE-2349.1.wip.txt > > > when a job has many input paths - listStatus - or the improved > listLocatedStatus - calls (invoked from the getSplits() method) can take a > long time. Most of the time is spent waiting for the previous call to > complete and then dispatching the next call. > This can be greatly speeded up by dispatching multiple calls at once (via > executors). If the same filesystem client is used - then the calls are much > better pipelined (since calls are serialized) and don't impose extra burden > on the namenode while at the same time greatly reducing the latency to the > client. In a simple test on non-peak hours, this resulted in the getSplits() > time reducing from about 3s to about 0.5s. -- This message was sent by Atlassian JIRA (v6.1.5#6160)