Tuesday, 7 July 2009

More on Weblogic Muxers

This is a follow-up to an earlier article which detailed the Weblogic Socket Muxer pattern in thread dumps.

Another ERROR pattern associated with Muxers is shown below

####<Jun 23, 2009 9:25:24 AM BST> <Error> <Socket> <d001> <managed1> <ExecuteThread: '0' for queue: 'weblogic.socket.Muxer'> <<WLS Kernel>>
<BEA-000403> <IOException occurred on socket: Socket[addr=/,port=1950,localport=61002]
java.net.SocketException: Connection refused.
java.net.SocketException: Connection refused
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream.java:129)
at weblogic.socket.SocketMuxer.readReadySocketOnce(SocketMuxer.java:672)
at weblogic.socket.SocketMuxer.readReadySocket(SocketMuxer.java:648)
at weblogic.socket.PosixSocketMuxer.processSockets(PosixSocketMuxer.java:123)
at weblogic.socket.SocketReaderRequest.execute(SocketReaderRequest.java:32)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:219)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:178)

As written in an earlier post, each incoming request on a TCP socket uses one File Descriptor.

We monitored the File Descriptors available to this Weblogic server using

Here the Weblogic pid = 8359

/usr/proc/bin/pfiles 8359 | grep rlimit


ls /proc/8359/fd | wc –l


The first command shows that 1024 FDs are allocated to this process, and the second shows how many are being used in real-time.

A plot of the second value during high load times shows the FDs go up to 900+ in use and hence a resolution used in this case is to increase the number of FDs.

A recommended value is to increase it to 8192.