FREEZEGROUP(3PVM) PVM Version 3.4 FREEZEGROUP(3PVM)NAMEpvm_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 subse‐
quent 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 struc‐
tures. 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 ALSOpvm_barrier(3PVM), pvm_lvgroup(3PVM)
16 March 1995 FREEZEGROUP(3PVM)
