bionic (3) pvm_reg_tasker.3PVM.gz

NAME

       pvm_reg_tasker - Register task as PVM task starter.

SYNOPSIS

       C    #include <pvmsdpro.h>

            int cc = pvm_reg_tasker()

       Fortran   Not Available

DESCRIPTION

       Registers  the calling task as a PVM task starter.  When a tasker is registered with a pvmd, and the pvmd
       receives a DM_EXEC message, instead of fork()ing and exec()ing the task itself, it passes  a  message  to
       the tasker, which does the dirty work and sends a message back to the pvmd.

       Note:   If  this  doesn't  make  sense, don't worry about it.  This function is for folks who are writing
       stuff like debugger servers and so on.  For a more complete explanation of  what's  going  on  here,  you
       should refer to the PVM source code and/or user guide section on implementation; this is only a man page.
       That said...

       When the pvmd receives a DM_EXEC message (request  to  exec  new  tasks),  it  searches  epath  (the  PVM
       executable  search  path)  for the file name.  If it finds the file, it then either attempts to start the
       processes (using fork() and exec()) or, if a tasker has registered, sends it a SM_STTASK message.

       The format of the SM_STTASK message is:
           int tid               // of task
           int flags             // as passed to spawn()
           string path           // absolute path of the executable
           int argc              // number of args to process
           string argv[argc]     // args
           int nenv              // number of envars to pass to task
           string env[nenv]      // environment strings

       The tasker must attempt to start the process when it gets one of  these  messages.   The  tasker  doesn't
       reply  to  the  pvmd if the task is successfully started; the task will reconnect to the pvmd on its own,
       using the cookie in envar PVMEPID to identify itself to the pvmd.

       The tasker must send a SM_TASKX message to the pvmd when any task that it owns (has started) exits, or if
       it can't start a particular task.  The format of the SM_TASKX message is:

           int tid               // of task
           int status            // the Unix exit status (from wait())
           int u_sec             // user time used by the task, seconds
           int u_usec            // microseconds
           int s_sec             // system time used by the task, seconds
           int s_usec            // microseconds

       The  tasker task must use pvm_setopt(PvmResvTids, 1) to allow sending reserved messages.  Messages should
       be packed using encoding PvmDataDefault to ensure they can be unpacked anywhere in the system.

       pvm_reg_tasker() returns PvmOk when successful.

SEE ALSO

       pvm_spawn(3PVM), pvm_tasks(3PVM),

                                                 16 March, 1994                                 REG_TASKER(3PVM)