Block report times from datanodes could converge to same time.
-----------------------------------------------------------------
Key: HADOOP-4971
URL: https://issues.apache.org/jira/browse/HADOOP-4971
Project: Hadoop Core
Issue Type: Bug
Components: dfs
Affects Versions: 0.18.0
Reporter: Raghu Angadi
Assignee: Raghu Angadi
Priority: Blocker
Fix For: 0.18.3
Datanode block reports take quite a bit of memory to process at the namenode.
After the inital report, DNs pick a random time to spread this load across at
the NN. This normally works fine.
Block reports are sent inside "offerService()" thread in DN. If for some reason
this thread was stuck for long time (comparable to block report interval), and
same thing happens on many DNs, all of them get back to the loop at the same
time and start sending block report then and every hour at the same time.
RPC server and clients in 0.18 can handle this situation fine. But since this
is a memory intensive RPC it lead to large GC delays at the NN. We don't know
yet why offerService therads seemed to be stuck, but DN should re-randomize it
block report time in such cases.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
