Routine:	barrier

Description:	This function synchronizes all nodes within a zone.
		A node waits at the barrier until all the other nodes
		in the zone have called barrier with the same barrier
		id.

		Every barrier has an id number, if no number is given
		the default is specified.  Barriers only match if
		the barrier id matches.  Valid id numbers are from
		1 to 24.  Providing barrier ids in a parallel script
		helps to verify program correctness (by causing deadlock
		for incorrect programs).  If no barrier ids are provided,
		then any barrier will match any other barrier in the
		script.  A timeout in seconds can be provided to barrier
		commands, otherwise the default timeout value is used.

Usage:		barrier [barrier_id [timeout_seconds]]

Example:	// wait at barrier 7 for a maximum of one hour
		barrier 7 3600

See also:	barrierall, paron

(C) Pittsburgh Supercomputing Center (PSC)
Revised: Sep 3, 1996
URL file://www.psc.edu/general/software/packages/genesis/barrier.txt
