[HADOOP-7256] Resource leak during failure scenario of closing of resources.

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 0.20.2
• Fix Version/s: 2.9.0, 3.0.0-alpha1
• Component/s: util
• Hadoop Flags: Reviewed
• Assignee: ramkrishna.s.vasudevan
• Reporter: ramkrishna.s.vasudevan
• Created: 03/May/11 15:18
• Updated: 02/Oct/19 17:13
• Resolved: 22/Sep/12 20:35

Description

Problem Statement:
===============
There are chances of resource leak and stream not getting closed
Take the case when after copying data we try to close the Input and output stream followed by closing of the socket.
Suppose an exception occurs while closing the input stream(due to runtime exception) then the subsequent operations of closing the output stream and socket may not happen and there is a chance of resource leak.

Scenario
=======
During long run of map reduce jobs, the copyFromLocalFile() api is getting called.
Here we found some exceptions happening. As a result of this we found the lsof value raising leading to resource leak.

Solution:
=======
While doing a close operation of any resource catch the RuntimeException also rather than catching the IOException alone.

Additionally there are places where we try to close a resource in the catch block.
If this close fails, we just throw and come out of the current flow.
In order to avoid this, we can carry out the close operation in the finally block.

Probable reasons for getting RunTimeExceptions:
=====================================
We may get runtime exception from customised hadoop streams like FSDataOutputStream.close() . So better to handle RunTimeExceptions also.

Issue Links

• breaks: HADOOP-13118 Fix IOUtils#cleanup and IOUtils#closeStream javadoc
• relates to: HADOOP-9226 IOUtils.CloseQuietly() to intercept RuntimeExceptions as well as IOExceptions