truss Command

You can use the truss command to check if a process is hung. The truss command must be run by the owner of the process or by root.

Use the following command syntax to check if a process is hung:

# truss [ -t syscall ] –p pid

–t syscall

Selects system calls to trace

–p pid

Indicates the PID of the process to be traced

syscall is a comma-separated list of system calls to be traced. Starting the list with an ! character excludes the listed system calls from the trace. For more information about the available options, see the truss (1) man page.

# /usr/bin/truss -p 243
poll(0x00024D50, 2, -1)         (sleeping...)

The example shows that the process is waiting for another connection request, which is a normal response. If the response does not change after a new connection request has been made, the process could be hung.

For information about restarting the NFS service, see How to Restart NFS Service. For information about troubleshooting a hung process, see NFS Troubleshooting Procedures.