We're seeing a distinct lack of performance with the DBAppender.

Although it works fine in a single threaded environment, in a multi-threaded environment it slows down considerably. We've done some investigation, and narrowed it down to the pair of synchronized calls to subAppend() and selectEventId() (lines 107->110).

I've had a look at this, and can see no reason for these to be synchronized;

If using the JDBC3 getGeneratedKeys() method then as this applies to the thread specific statement there is no need to be synchronized.

All the "Dialect" based calls are also connection specific; in detail;

H2, HSQLDB and MySQL all call a database function, which is connection specific.

MsSQL and Sybase both select a connection specific variable.

Oracle and PostgreSQL both select the currval from a sequence, which again is connection specific.

Having removed the synchronisation, we're seeing vastly improved logging throughput in our application.

So to summarise; there is unnecessary synchronisation in the DBAppender that slows down multi-threaded applications; removing that synchronisation will improve performance in multi-threaded applications with no side affects.