fcntl using F_SETLKW flag hangs

[CIS Unix (Keith Daley)]

Running HP-UX 11 on a K360, using cobol V4.1 revision 30.
When you run the animator it hangs, tusc shows that it opens a file (the file is on an NFS mounted filesytem) and then runs the fcntl system call with F_SETLKW as an argument.
Does anyone know of any problems with fcntl and NFS ?

[Ralph Grothe]

I'm no expert in NFS, just a wild guess.
I could imagine that your application cannot acquire a file lock on a remotely exported filesystem (I'm not sure if this can be guaranteed by the NFS protocol anyway?).
Better consult the man pages of nfs, nfsd, mount_nfs, fcntl...

[CIS Unix (Keith Daley)]

This is only a problem on some systems, it works on other systems that are using a different NFS server. So the problem can't be a limitation with NFS or the fcntl system call.

[Klaus Crusius]

The NFS locks are managed by the rcp.lockd daemons on both client and server sites. Lock at man lockd.
Maybe the lockd processes are not running on one or the other machine. In this case the lock request is "delayed until the server recovers", might be a long time!

Klaus