MySQL Bugs: #58444: NullPointerException in com.mysql.jdbc.StatementImpl.closeAllOpenResults

Bug #58444	NullPointerException in com.mysql.jdbc.StatementImpl.closeAllOpenResults
Submitted:	24 Nov 2010 7:30	Modified:	25 Mar 2013 12:26
Reporter:	Mikiya Okuno	Email Updates:
Status:	Can't repeat	Impact on me:	None
Category:	Connector / J	Severity:	S3 (Non-critical)
Version:		OS:	Any
Assigned to:	Alexander Soklakov	CPU Architecture:	Any

Description:
Since com.mysql.jdbc.StatementImpl.realClose isn't thread-safe, it causes NullPointerException when called from multiple threads at a time.

realClose returns if isClosed member is false. But, isClosed member isn't protected by any lock, so multiple threads can go through logics to close the target Statement at the same time. If one thread set openResults = null, then other thread may cause NullPointerException in closeAllOpenResults method.

How to repeat:
Call Statement#close simultaneously on Statement instance which has not been closed yet.

Suggested fix:
Synchronize isClosed member.

Is there a legitimate reason to share a statement between threads? While this could be made thread-safe, it would be at the expense of slowing down the 99% of use cases that don't use a questionable usage pattern.

Hi Mikiya,

I was not able to reproduce this failure with latest C/J, so I close this report as "Can't repeat". But feel free to reopen if you find that the problem still exists.