Jdbc hangs on first connection only

Question

We are running a number of java applications against an Oracle 11g database. The applications are all running on disk-less machines. We are seeing weird behaviour where the first connection, and only the first connection for each application hangs.
We even see this for sqldeveloper, if you start sqldeveloper and try to make a connection, it sits there with the bar going back and forth until you click cancel, at which point every connection you attempt to make after that is fine.
We are pretty sure this has to be a problem with JDBC running on a disk-less machine. We have some ODBC applications that run fine on these disk-less machines and we can run the java applications fine on a machine with a disk that has the same architecture as the one without.
We have tried to turn on JDBC logging by using the ojdbc5_g.jar and setting oracle.jdbc.Trace=true, but have had no success, we have also tried doing it programatically by setting DriverManager.setLogger() and setting it to System.out, but haven't seen anything new.
We are using the oracle:thin driver and are running on red hat 5.0 with Java 1.5 and a 64 bit architecture, against Oracle 11g . Does anyone have any thoughts on what is going on?
Edited by: user538801 on Aug 11, 2009 12:15 PM

Answer 1

We found it, it was a pretty obscure issue. The JDBC getConnection() method makes a call to the random number generator. This call hangs due to the system entropy being 0 on the disk-less blades, when the JVM starts up it waits on the first call to the random number generator for the system entropy to get above a certain threshold which it doesn't do.
The solution was to use a different random number generator, by default the JVM uses/dev/random which requires sufficient entropy to seed the first call, we changed it to /dev/urandom by setting java.security.egd which is slightly less random, but does not hang on the first call.