[DERBY-4723] Using an instance lock to protect static shared data in EmbedPooledConnection

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 10.5.1.1
• Fix Version/s: 10.5.3.2, 10.6.2.4, 10.7.1.1
• Component/s: JDBC
• Assignee: Kristian Waagan
• Reporter: Wendy Feng
• Created: 29/Jun/10 09:36
• Updated: 17/Jun/13 09:19
• Resolved: 15/Feb/11 14:00

Description

EmbedPooledConnection has the unsafe synchronization as follow.

private static int idCounter = 0;

private synchronized int nextId()

{ return idCounter++; }

idCounter is a static shared data, and it is not proper to use a instance lock to protect it, especially when two instance of the class are created.

it would be more safer to write this instead:

private static synchronized int nextId()
{ return idCounter++; }

Issue Links

• is required by: DERBY-4994 10.5 backport effort issue (2011)