pvm_barrier(3pvm) [debian man page]

BARRIER(3PVM)							  PVM Version 3.4						     BARRIER(3PVM)

NAME

       pvm_barrier - Blocks the calling process until all processes in a group have called it.

SYNOPSIS

       C    int info = pvm_barrier( char *group, int count )

       Fortran	 call pvmfbarrier( group, count, info )

PARAMETERS

       group   Character string group name. The group must exist and the calling process must be a member of the group.

       count   Integer	specifying the number of group members that must call pvm_barrier before they are all released. Though not required, count
	       is expected to be the total number of members of the specified group.

       info    Integer status code returned by the routine.  Values less than zero indicate an error.

DESCRIPTION

       The routine pvm_barrier blocks the calling process until count members of the  group  have  called  pvm_barrier.   The  count  argument	is
       required  because  processes could be joining the given group after other processes have called pvm_barrier. Thus PVM doesn't know how many
       group members to wait for at any given instant. Although count can be set less, it is typically the total number of members of  the  group.
       So  the	logical  function  of the pvm_barrier call is to provide a group synchronization.  During any given barrier call all participating
       group members must call barrier with the same count value.  Once a given barrier has been successfully passed, pvm_barrier  can	be  called
       again by the same group using the same group name.

       If pvm_barrier is successful, info will be 0. If some error occurs then info will be < 0.

EXAMPLES

       C:
	    inum = pvm_joingroup( "worker" );
		    .
		    .
	    info = pvm_barrier( "worker", 5 );

       Fortran:
	    CALL PVMFJOINGROUP( "shakers", INUM )
	    COUNT = 10
	    CALL PVMFBARRIER( "shakers", COUNT, INFO )

ERRORS

       These error conditions can be returned by pvm_barrier

       PvmSysErr
	      pvmd was not started or has crashed.

       PvmBadParam
	      giving a count < 1.

       PvmNoGroup
	      giving a non-existent group name.

       PvmNotInGroup
	      calling process is not in specified group.

SEE ALSO

       pvm_joingroup(3PVM)

								  30 August, 1993						     BARRIER(3PVM)

FREEZEGROUP(3PVM)						  PVM Version 3.4						 FREEZEGROUP(3PVM)

NAME

       pvm_freezegroup - Freezes dynamic group membership and caches info locally

SYNOPSIS

       C    int info = pvm_freezegroup( char *group , int size)

       Fortran	 call pvmffreezegroup( group, size, info )

PARAMETERS

       group   Character string group name of an existing group.

       size    Size of the group when it is frozen

       info    size of group on success. Values less than 0 indicate and error.

DESCRIPTION

       The  routine  pvm_freezegroup  makes  a	dynamic  group	named  group static. The group information is  then "cached" by all group members.
       pvm_freezegroup is a synchronizing routine and must be called by all group members to complete.	size indicates the size the dynamic  group
       should be when made static.  A value of -1 indicates that the current size of the group should be used.	info returns error information.

       Once a dynamic group has been frozen with pvm_freezegroup , all subsequent operations that can be satisfied with local data use the locally
       held information. For processes that are outside of the group, the first group call, e.g., pvm_bcast(), will cause the static group  infor-
       mation  to  be  copied  to the calling process.	Subsequent operations then use the local information. Barriers are still arbitrated by the
       group server.

       Group members should call  pvm_lvgroup  to leave the group and free any allocated structures that hold the  group  information.	 Processes
       not  in	the  group  may  call	pvm_lvgroup   to  free	any  locally allocated structures. In this case, an error code of PvmNotInGroup or
       PvmNoGroup will be returned to the caller.

       Barrier are always arbitrated by the group server, even if the group has been made static with  pvm_freezegroup.  If  a	process  leaves  a
       static  group  while  other  process are waiting at a barrier, then PvmNoGroup is returned to all processes waiting at the barrier.  Future
       barrier calls with the defunct static group, return the same error.

EXAMPLES

       C:
	       inum = pvm_joingroup("worker");
	    info = pvm_freezegroup( "worker", size );

       Fortran:
	       CALL PVMFJOINGROUP('group2', inum)
	    CALL PVMFFREEZEGROUP( 'group2', size, info )

ERRORS

       These error conditions can be returned by pvm_freezegroup

       PvmSysErr
	      pvmd was not started or has crashed.

       PvmBadParam
	      giving a NULL group name.

       PvmDupGroup
	      trying to freeze a group that is already frozen.

       PvmNotInGroup
	      trying to freeze a group that you are not in.

BUGS

       There is no way to unfreeze a group.

       Processes are not notified if a frozen group becomes invalid.

       Having a non-member process call pvm_lvgroup to free structures is a bit strange.

SEE ALSO

       pvm_barrier(3PVM), pvm_lvgroup(3PVM)

								   16 March 1995						 FREEZEGROUP(3PVM)