bad performance in LAN

Hi

I use BufferedInputStream and BufferedOutputStream to implement a specific JDBC driver for my middleware-basd database. It runs well until recently the system admins of my school upgrade the operation system (Redhat). Before the upgrade, the roundtrip time is only less than 5 ms in LAN. But after the upgrade, the roundtrip time goes beyond 30ms, even if the client and the server sockets are in the same machine.

I debugged it carefully. It seems that the sometimes inputStream.read() takes about 30ms, but sometimes it only takes 0-1 ms. I doubt that it is due to buffer size (I use 8192 for input and output)and the stream is not flush immediately. But even after I add outputStream.flush() in the server side, there is still the same problem.

I asked the system admin to change the operation system back to the original version. And the socket performance is fine.

I even tried a AF_UNIX socket (java codes based on JNI and C) between client and server in the same machine. Even with the new operation system, the performance is also good.

Can any experts give any suggestions?

thanks in advance.

[1149 byte] By [roylina] at [2007-10-3 0:38:51]