[HBASE-17468] unread messages in TCP connections - possible connection leak

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Duplicate
• Assignee: Unassigned
• Reporter: Shridhar Sahukar
• Created: 14/Jan/17 02:03
• Updated: 23/May/17 07:56
• Resolved: 23/May/17 07:56

Description

We are running HBase 1.2.0-cdh5.7.1 (Cloudera distribution).

On our Hadoop cluster, we are seeing that each HBase region server has large number of TCP connections to all the HDFS data nodes and all these connections have unread data in socket buffers. Some of these connections are also in CLOSE_WAIT or FIN_WAIT1 state while the rest are in ESTABLISHED state.

Looks like HBase is creating some connections requesting data from HDFS, but its forgetting about those connections before it could read the data. Thus the connections are left lingering around with large data stuck in their receive buffers. Also, it seems HDFS closes these connections after a while, but since there is data in receive buffer the connection is left in CLOSE_WAIT/FIN_WAIT1 states.

Below is a snapshot from one of the region servers:

1. 1. Total number of connections to HDFS (pid of region server is 143722)
      [bda@md-bdadev-42 hbase]$ sudo netstat -anp|grep 143722 | wc -l
      827

1. 1. Connections that are not in ESTABLISHED state
      [bda@md-bdadev-42 hbase]$ sudo netstat -anp|grep 143722 | grep -v ESTABLISHED | wc -l
      344

##Snapshot of some of these connections:
tcp 133887 0 146.1.180.43:48533 146.1.180.40:50010 ESTABLISHED 143722/java
tcp 82934 0 146.1.180.43:59647 146.1.180.42:50010 ESTABLISHED 143722/java
tcp 0 0 146.1.180.43:50761 146.1.180.27:2181 ESTABLISHED 143722/java
tcp 234084 0 146.1.180.43:58335 146.1.180.42:50010 ESTABLISHED 143722/java
tcp 967667 0 146.1.180.43:56136 146.1.180.68:50010 ESTABLISHED 143722/java
tcp 156037 0 146.1.180.43:59659 146.1.180.42:50010 ESTABLISHED 143722/java
tcp 212488 0 146.1.180.43:56810 146.1.180.48:50010 ESTABLISHED 143722/java
tcp 61871 0 146.1.180.43:53593 146.1.180.35:50010 ESTABLISHED 143722/java
tcp 121216 0 146.1.180.43:35324 146.1.180.38:50010 ESTABLISHED 143722/java
tcp 1 0 146.1.180.43:32982 146.1.180.42:50010 CLOSE_WAIT 143722/java
tcp 82934 0 146.1.180.43:42359 146.1.180.54:50010 ESTABLISHED 143722/java
tcp 159422 0 146.1.180.43:59731 146.1.180.42:50010 ESTABLISHED 143722/java
tcp 134573 0 146.1.180.43:60210 146.1.180.76:50010 ESTABLISHED 143722/java
tcp 82934 0 146.1.180.43:59713 146.1.180.42:50010 ESTABLISHED 143722/java
tcp 135765 0 146.1.180.43:44412 146.1.180.29:50010 ESTABLISHED 143722/java
tcp 161655 0 146.1.180.43:43117 146.1.180.42:50010 ESTABLISHED 143722/java
tcp 75990 0 146.1.180.43:59729 146.1.180.42:50010 ESTABLISHED 143722/java
tcp 78583 0 146.1.180.43:59971 146.1.180.42:50010 ESTABLISHED 143722/java
tcp 1 0 146.1.180.43:39893 146.1.180.67:50010 CLOSE_WAIT 143722/java
tcp 1 0 146.1.180.43:38834 146.1.180.47:50010 CLOSE_WAIT 143722/java
tcp 1 0 146.1.180.43:40707 146.1.180.50:50010 CLOSE_WAIT 143722/java
tcp 106102 0 146.1.180.43:48208 146.1.180.75:50010 ESTABLISHED 143722/java
tcp 332013 0 146.1.180.43:34795 146.1.180.37:50010 ESTABLISHED 143722/java
tcp 1 0 146.1.180.43:57644 146.1.180.67:50010 CLOSE_WAIT 143722/java
tcp 79119 0 146.1.180.43:54438 146.1.180.70:50010 ESTABLISHED 143722/java
tcp 77438 0 146.1.180.43:35259 146.1.180.38:50010 ESTABLISHED 143722/java
tcp 1 0 146.1.180.43:57579 146.1.180.41:50010 CLOSE_WAIT 143722/java
tcp 318091 0 146.1.180.43:60124 146.1.180.42:50010 ESTABLISHED 143722/java
tcp 1 0 146.1.180.43:51715 146.1.180.70:50010 CLOSE_WAIT 143722/java
tcp 126519 0 146.1.180.43:36389 146.1.180.49:50010 ESTABLISHED 143722/java
tcp 1 0 146.1.180.43:45656 146.1.180.75:50010 CLOSE_WAIT 143722/java
tcp 113720 0 146.1.180.43:59741 146.1.180.42:50010 ESTABLISHED 143722/java
tcp 74599 0 146.1.180.43:44192 146.1.180.60:50010 ESTABLISHED 143722/java
tcp 131224 0 146.1.180.43:53708 146.1.180.44:50010 ESTABLISHED 143722/java
tcp 1433915 0 146.1.180.43:57140 146.1.180.67:50010 ESTABLISHED 143722/java