The PostgreSQL JDBC ( bundled with 7.1 RC3 at least) driver makes use of Java's 
ThreadLocal class in the .../jdbc2/PreparedStatement.java class to hold onto 
DateFormat classes used during the setTImestamp() and 
setDate() calls. Sun's J2SE 1.3 has a major bug in the implementation of ThreadLocal 
in which progressive use leaks more and more memory.

This means that as more PreparedStatements are used, more and more memory is leaked, 
and at a high rate. Eventually, the Java VM runs out of memory and any applications 
running within it will crash and burn.

Our stress tests indicate that our application running on top of the Orion application 
server will crash with an hour after taking up all available memory when using this 
driver.

A solution is to NOT use ThreadLocal in the PreparedStatement class. This solution 
works because ThreadLocal is used as an "optimization" to avoid allocating the 
DateFormat classes multiple times. On our site, we 
patched the RC3 JDBC driver to not use the ThreadLocal object and everything is 
runnning fine with no perceivable performance loss.

Sun's bug report is here:


http://developer.java.sun.com/developer/bugParade/bugs/4414045.html



Gerald.



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