Some people have been experiencing problems with F_SETLKW64/fcntl when running Samba on Solaris. The built-in file-locking mechanism was not scalable. Performance would degrade to the point where processes would get into loops of trying to lock a file. It would try a lock, then fail, then try again. The lock attempt was failing before the grant was occurring. The visible manifestation of this was a handful of processes stealing all of the CPU, and when they were trussed, they would be stuck in F_SETLKW64 loops.

Please check with Sun support for current patches needed to fix this bug. The patch revision for 2.6 is 105181-34, for 8 is 108528-19, and for 9 is 112233-04. After the installation of these patches, it is recommended to reconfigure and rebuild Samba.

Thanks to Joe Meslovich for reporting this.