r369: - Replace conflict-checking via "ps" with per-parcel lockfile using fcntl whole-file locks.  Right now we're overly conservative: any two operations affecting the same parcel will conflict.  On the other hand, the old code would not catch conflicting operations performed on different machines using the same NFS or AFS home directory, and this code will.
r369: - Replace conflict-checking via "ps" with per-parcel lockfile using fcntl
whole-file locks.  Right now we're overly conservative: any two operations
affecting the same parcel will conflict.  On the other hand, the old
code would not catch conflicting operations performed on different
machines using the same NFS or AFS home directory, and this code will.

Because perl doesn't give us an abstraction for struct flock, acquire_lock()
will likely break on non-Linux systems.

cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr