[HDFS-285] limit concurrent connections(data serving thread) in one datanode

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Not A Problem
• Assignee: Unassigned
• Reporter: Luo Ning
• Created: 17/Jul/08 09:50
• Updated: 03/Feb/14 11:15
• Resolved: 03/Feb/14 11:15

Description

i'm here after HADOOP-2341 and HADOOP-2346, in my hbase env, many opening mapfiles cause datanode OOME(stack memory), because 2000+ data serving threads in datanode process.

although HADOOP-2346 has implements timeouts, it will be some situation many connection created before the read timeout(default 6min) reach. like hbase does, it open all files on regionserver startup.

limit concurrent connections(data serving thread) will make datanode more stable. and i think it could be done in SocketIOWithTimeout$SelectorPool#select:
1. in SelectorPool#select, record all waiting SelectorInfo instances in a List at the beginning, and remove it after 'Selector#select' done.
2. before real 'select', do a limitation check, if reached, close the first selectorInfo.