3.2   Process management primitives

• int tid = pvm_mytid (void)
call pvmfmytid (tid)
  • Enrolls this process into PVM on its first call and generates a unique tid
  • It returns the tid of this process and can be call multiple times
  • pvm_mytid() must be call before any other calls in an application
  • If PVM has not been started before, it returns an error code
  • Example in C:

    if (me = pvm_mytid () < 0)
        printf ("error in enrolling\n") ; 
    else 
        printf ("success, I am %d\n", me) ;                 
                

  • Example in Fortran:

    CALL PVMFMYTID (ME)
    IF (ME .LT. 0) THEN 
        WRITE (*,*) 'error in enrolling'
    ELSE 
        WRITE (*,*) 'success, I am ', ME
    ENDIF
                

• int info = pvm_exit (void)
call pvmfexit (info)
  • Tells the local daemon that the process in leaving PVM
  • Does not kill the process, which can continue to perform task just like any other Unix process
  • It should be called by all PVM processes before they stop or exit for good
  • It must be called by processes that were not started with pvm_spawn;
    otherwise PVM will not know if the process has crashed or exited normally
  • Example in C:

    /* program done */
    pvm_exit () ; 
    exit () ;                
              

  • Example in Fortran:

    C    **program done**
         CALL PVMEXIT (INFO)
         STOP
              

• int numt = pvm_spawn (char *task, char **argv,
   int flag, char *where, int ntask, int *tids)
call pvmfspawn (task, flag, where, ntask, tids, numt)
  • It starts up ntask copies of an executable file task on the virtual machine:

    pvm3/bin/$PVMARCH/task argv
    

  • argv is a pointer to a NULL terminated array of arguments to task
  • The flag argument is used to specify options, and is sum of

    PvmTaskDefault 0

    PVM chooses where to spawn processes (in a cyclic fashion) (where is ignored)

    PvmTaskHost 1

    the where argument specifies a particular host to spawn on

    PvMTaskArch 2

    the where argument specifies a type of architecture to spawn on

    PvmTaskDebug 4

    starts these processes up under debugger

    PvmTaskTrace 8

    the PVM calls in these processes will generate trace data

    PvmMppFront 16

    starts the processes on MPP front-end

    PvmHostCompl 32

    uses complement host set

  • On return, numt is set to the number of tasks successfully spawned or an error code if no tasks could be started
  • It returns a vector of the spawned tasks' tids

•  
  • On multiprocessors, restrictions apply
  • Examples in C

    numtr = pvm_spawn ("host", 0, PvmTaskHost, 
                       "ms3", 1, &tid[0]) ;
    numtr = pvm_spawn ("host", 0, 
                       PvmTaskHost+PvmTaskDebug, 
                       "ms3", 1, &tid[0]) ;
    numtr = pvm_spawn ("node", 0, PvmTaskArch, 
                       "SUN4", 1, &tid[i]) ;
    numtr = pvm_spawn ("FEM1", args, 0, 0, 16, tids) ;
    numtr = pvm_spawn ("pde", 0, PvmTaskHost, 
                       "paragon.lifl.fr", 512, tids) ;
              

  • Examples in Fortran

    CALL PVMFSPAWN ("host", PVMTASKHOST, 
                       "ms3", 1, TID, NUMTR) 
    CALL PVMFSPAWN ("host", 
                       PVMTASKHOST+PVMTASKDEBUG, 
                       "ms3", 1, TID, NUMTR) 
    CALL PVMFSPAWN ("node", PVMTASKARCH, 
                       "SUN4", 1, TID, NUMTR) 
    CALL PVMFSPAWN ("FEM1" 0, 0, 16, TIDS, NUMTR) 
    CALL PVMFSPAWN ("pde" PVMTASKHOST, 
                       "paragon.lifl.fr", 512,
                       TIDS, NUMTR) 
              

      program firstpvm 
      include 'fpvm3.h'
      integer nprocs, info, tids (0:20), mytid
      call pvmfmytid (mytid)
      call pvmfparent (tids(0))
      if (tids (0) .lt. 0) then
C***  In the master code ***
         tids(0) = mytid
         read (*,*), nprocs
         call pvmfspawn ('a.out', PVMTASKDEFAULT, 
    &                 '*', nproc-1, tids(1), numt)
         ....
      else
C***  In the slave code ***
         ....
      end if 
      call pvmfexit (info)
      end      

• int info = pvm_kill (int tid)
call pvmfkill (tid, info)
  • Kills some other PVM task identified by tid
    
    
  • On Unix system, sends a terminate (SIGKILL) signal to the PVM process identified by tid
  • It is not designed to kill the calling task (which could be accomplished by calling pvm_exit() followed by exit())
  • A value less than zero for info indicates an error