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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<TITLE> S-Lang PVM Module Reference: Master-Slave Function Reference</TITLE>
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<HR>
<H2><A NAME="s4">4.</A> <A HREF="pvm.html#toc4">Master-Slave Function Reference</A></H2>
<H2><A NAME="pvm_ms_kill"></A> <A NAME="ss4.1">4.1</A> <A HREF="pvm.html#toc4.1"><B>pvm_ms_kill</B></A>
</H2>
<P>
<DL>
<DT><B> Synopsis </B><DD><P>Send a "task complete" message to a specific task</P>
<DT><B> Usage </B><DD><P><CODE>pvm_ms_kill (Int_Type mtid, Int_Type stid)</CODE></P>
<DT><B> Description </B><DD><P>This function may be used to send a "task complete" message
to a specific PVM process. The first argument gives
the task identifier of the destination process. The second
argument gives the task identifier of the sending process.</P>
<DT><B> Example </B><DD><P>
<BLOCKQUOTE><CODE>
<PRE>
tid = pvm_mytid ();
ptid = pvm_parent ();
pvm_ms_kill (ptid, tid);
</PRE>
</CODE></BLOCKQUOTE>
</P>
<DT><B> See Also </B><DD><P><CODE>
<A HREF="#pvm_ms_slave_exit">pvm_ms_slave_exit</A></CODE></P>
</DL>
</P>
<H2><A NAME="pvm_ms_set_num_processes_per_host"></A> <A NAME="ss4.2">4.2</A> <A HREF="pvm.html#toc4.2"><B>pvm_ms_set_num_processes_per_host</B></A>
</H2>
<P>
<DL>
<DT><B> Synopsis </B><DD><P>Set the maximum number of simultaneous processes per host</P>
<DT><B> Usage </B><DD><P><CODE>pvm_ms_set_num_processes_per_host (Int_Type num_processes)</CODE></P>
<DT><B> Description </B><DD><P>This function is used to set the maximum number of simultaneous
processes per host. The master process normally runs as many
simultaneous processes as possible; by setting the maximum
number of simultaneous processes per host, one can limit the
processing load per host.</P>
<DT><B> Example </B><DD><P>
<BLOCKQUOTE><CODE>
<PRE>
pvm_ms_set_num_processes_per_host (2);
</PRE>
</CODE></BLOCKQUOTE>
</P>
<DT><B> See Also </B><DD><P><CODE>
<A HREF="#pvm_ms_run_master">pvm_ms_run_master</A></CODE></P>
</DL>
</P>
<H2><A NAME="pvm_ms_set_debug"></A> <A NAME="ss4.3">4.3</A> <A HREF="pvm.html#toc4.3"><B>pvm_ms_set_debug</B></A>
</H2>
<P>
<DL>
<DT><B> Synopsis </B><DD><P>Set the debug flag</P>
<DT><B> Usage </B><DD><P><CODE>pvm_ms_set_debug (Int_Type debug)</CODE></P>
<DT><B> Description </B><DD><P>This function may be used to control whether debugging
information is printed out during execution. Debugging
information is printed if the flag is non-zero.</P>
<DT><B> Example </B><DD><P>
<BLOCKQUOTE><CODE>
<PRE>
pvm_ms_set_debug (1);
</PRE>
</CODE></BLOCKQUOTE>
</P>
<DT><B> See Also </B><DD><P><CODE>
<A HREF="#pvm_ms_set_num_processes_per_host">pvm_ms_set_num_processes_per_host</A></CODE></P>
</DL>
</P>
<H2><A NAME="pvm_ms_slave_exit"></A> <A NAME="ss4.4">4.4</A> <A HREF="pvm.html#toc4.4"><B>pvm_ms_slave_exit</B></A>
</H2>
<P>
<DL>
<DT><B> Synopsis </B><DD><P>Cause a normal exit of a slave process from the PVM</P>
<DT><B> Usage </B><DD><P><CODE>pvm_ms_slave_exit (Int_Type exit_status)</CODE></P>
<DT><B> Description </B><DD><P>To exit the PVM, a slave process calls this function to
send its exit status to the parent process and to notify
the local <CODE>pvmd</CODE> of its exit.</P>
<DT><B> Example </B><DD><P>
<BLOCKQUOTE><CODE>
<PRE>
pvm_ms_slave_exit (exit_status);
</PRE>
</CODE></BLOCKQUOTE>
</P>
<DT><B> See Also </B><DD><P><CODE>
<A HREF="#pvm_ms_run_slave">pvm_ms_run_slave</A></CODE></P>
</DL>
</P>
<H2><A NAME="pvm_ms_run_slave"></A> <A NAME="ss4.5">4.5</A> <A HREF="pvm.html#toc4.5"><B>pvm_ms_run_slave</B></A>
</H2>
<P>
<DL>
<DT><B> Synopsis </B><DD><P>Execute the slave's assigned task in a subshell, then exit the PVM</P>
<DT><B> Usage </B><DD><P><CODE>pvm_ms_run_slave (String_Type argv[])</CODE></P>
<DT><B> Description </B><DD><P>A slave process calls this function to run a command in a
subshell and then exit the PVM. The command line is
constructed by concatenting the elements of an array of
strings, <CODE>argv</CODE>, delimited by spaces. The integer return
value from the <CODE>system</CODE> call provides the exit status
for the slave process. After sending this value to its
parent process, the slave notifies the PVM and exits.</P>
<DT><B> Example </B><DD><P>
<BLOCKQUOTE><CODE>
<PRE>
pvm_ms_run_slave (argv);
</PRE>
</CODE></BLOCKQUOTE>
</P>
<DT><B> See Also </B><DD><P><CODE>
<A HREF="#pvm_ms_slave_exit">pvm_ms_slave_exit</A></CODE></P>
</DL>
</P>
<H2><A NAME="pvm_ms_run_master"></A> <A NAME="ss4.6">4.6</A> <A HREF="pvm.html#toc4.6"><B>pvm_ms_run_master</B></A>
</H2>
<P>
<DL>
<DT><B> Synopsis </B><DD><P>Submit a list of tasks to the PVM</P>
<DT><B> Usage </B><DD><P><CODE>Struct_Type exit_status[] = pvm_ms_run_master (String_Type pgms[])</CODE></P>
<DT><B> Description </B><DD><P>This function is used to submit a managed list of tasks to
the PVM. The task list manager will try to ensure that all
tasks are completed and, upon completion of the task list,
will return an array of structures containing information
about the results of each task.</P>
<DT><B> Example </B><DD><P>To run the Unix command <I>ps xu</I> on a number of different
hosts:
<BLOCKQUOTE><CODE>
<PRE>
variable slave_argv = Array_Type[n];
slave_argv[*] = ["ps", "axu"];
exit_status = pvm_ms_run_master (slave_argv);
</PRE>
</CODE></BLOCKQUOTE>
</P>
<DT><B> See Also </B><DD><P><CODE>
<A HREF="#pvm_ms_add_new_slave">pvm_ms_add_new_slave</A></CODE></P>
</DL>
</P>
<H2><A NAME="pvm_ms_add_new_slave"></A> <A NAME="ss4.7">4.7</A> <A HREF="pvm.html#toc4.7"><B>pvm_ms_add_new_slave</B></A>
</H2>
<P>
<DL>
<DT><B> Synopsis </B><DD><P>Add a new slave to the managed list</P>
<DT><B> Usage </B><DD><P><CODE>pvm_ms_add_new_slave (String_Type argv[])</CODE></P>
<DT><B> Description </B><DD><P>This function may be used to add a new slave process
while pvm_ms_run_master() is running, usually as a result
of handling a message.</P>
<DT><B> Example </B><DD><P>
<BLOCKQUOTE><CODE>
<PRE>
pvm_ms_add_new_slave ("vex");
</PRE>
</CODE></BLOCKQUOTE>
</P>
<DT><B> See Also </B><DD><P><CODE>
<A HREF="#pvm_ms_run_master">pvm_ms_run_master</A></CODE></P>
</DL>
</P>
<H2><A NAME="pvm_ms_set_message_callback"></A> <A NAME="ss4.8">4.8</A> <A HREF="pvm.html#toc4.8"><B>pvm_ms_set_message_callback</B></A>
</H2>
<P>
<DL>
<DT><B> Synopsis </B><DD><P>Set a callback for handling user-defined messages</P>
<DT><B> Usage </B><DD><P><CODE>pvm_ms_set_message_callback (Ref_Type func)</CODE></P>
<DT><B> Description </B><DD><P>This function may be used to handle user-defined messages
be sent from slave processes back to the master process.</P>
<DT><B> Example </B><DD><P>
<BLOCKQUOTE><CODE>
<PRE>
static define handle_user_message (msgid, tid)
{
switch (msgid)
{
case USER_SLAVE_RESULT:
recv_results (tid);
start_task (tid);
}
{
case USER_SLAVE_READY:
start_task (tid);
}
{
% default:
return 0;
}
return 1;
}
pvm_ms_set_message_callback (&handle_user_message);
</PRE>
</CODE></BLOCKQUOTE>
</P>
<DT><B> See Also </B><DD><P><CODE>
<A HREF="#pvm_ms_set_idle_host_callback">pvm_ms_set_idle_host_callback</A>,
<A HREF="#pvm_ms_set_slave_exit_failed_callback">pvm_ms_set_slave_exit_failed_callback</A></CODE></P>
</DL>
</P>
<H2><A NAME="pvm_ms_set_slave_exit_failed_callback"></A> <A NAME="ss4.9">4.9</A> <A HREF="pvm.html#toc4.9"><B>pvm_ms_set_slave_exit_failed_callback</B></A>
</H2>
<P>
<DL>
<DT><B> Synopsis </B><DD><P>Set a hook to be called when a slave exits on failure</P>
<DT><B> Usage </B><DD><P><CODE>pvm_ms_set_slave_exit_failed_callback (Ref_Type func)</CODE></P>
<DT><B> Description </B><DD><P>This function may be used to have the master process perform a
specified action whenever a slave process exits without having
completed its assigned task.</P>
<P>This is primarily useful in the context where each command-line
submitted to <CODE>pvm_ms_run_master</CODE> represents a task which
itself communicates with the PVM, performing potentially many
additional tasks which are independently managed by the
process that called <CODE>pvm_ms_run_master</CODE>.</P>
<P>For example, consider a case in which initialization of slave
processes is very expensive but, once initialized, a single
slave process may perform many tasks. In this case, the
master process may spawn a small number of slaves and then
repeatedly send each slave a task to perform. Each slave
performs its task, sends the result to the master, and then
waits for another task. The managing process must keep track
of which tasks have been completed and which remain. If a
slave exits while working on a task, it is important that the
manager process be notified that that task in progress was not
completed and that it should be reassigned to another slave.</P>
<DT><B> Example </B><DD><P>
<BLOCKQUOTE><CODE>
<PRE>
static define slave_exit_failed_callback (msgid, tid)
{
variable t = find_task_tid (tid);
if (orelse {t == NULL} {t.status == FINISHED})
return;
% mark the unfinished task "READY" so that it will
% be assigned to another slave
t.tid = -1;
t.status = READY;
}
pvm_ms_set_slave_exit_failed_callback (&slave_exit_failed_callback);
</PRE>
</CODE></BLOCKQUOTE>
</P>
<DT><B> See Also </B><DD><P><CODE>
<A HREF="#pvm_ms_set_message_callback">pvm_ms_set_message_callback</A></CODE></P>
</DL>
</P>
<H2><A NAME="pvm_ms_set_slave_spawned_callback"></A> <A NAME="ss4.10">4.10</A> <A HREF="pvm.html#toc4.10"><B>pvm_ms_set_slave_spawned_callback</B></A>
</H2>
<P>
<DL>
<DT><B> Synopsis </B><DD><P>Set the slave spawned callback hook</P>
<DT><B> Usage </B><DD><P><CODE>pvm_ms_set_slave_spawned_callback (Ref_Type func)</CODE></P>
<DT><B> Description </B><DD><P>This function may be used to specify a callback function to be
called whenever a slave process has been spawned. The callback
function will be called with three arguments: the slave task
id, the name of the host running the slave process, and an
array of strings representing the argument list passed to the
slave.</P>
<DT><B> Example </B><DD><P>
<BLOCKQUOTE><CODE>
<PRE>
static define slave_spawned_callback (tid, host, argv)
{
vmessage ("Slave running %s spawned on %s with task-id %d",
argv[0], host, tid);
}
pvm_ms_set_slave_spawned_callback (&slave_spawned_callback);
</PRE>
</CODE></BLOCKQUOTE>
</P>
<DT><B> See Also </B><DD><P><CODE>
<A HREF="#pvm_ms_set_message_callback">pvm_ms_set_message_callback</A></CODE></P>
</DL>
</P>
<H2><A NAME="pvm_ms_set_idle_host_callback"></A> <A NAME="ss4.11">4.11</A> <A HREF="pvm.html#toc4.11"><B>pvm_ms_set_idle_host_callback</B></A>
</H2>
<P>
<DL>
<DT><B> Synopsis </B><DD><P>Set the idle host hook</P>
<DT><B> Usage </B><DD><P><CODE>pvm_ms_set_idle_host_callback (Ref_Type func)</CODE></P>
<DT><B> Description </B><DD><P>This function may be used to specify a callback function to be
called whenever a new host is added to the virtual machine.</P>
<DT><B> Example </B><DD><P>
<BLOCKQUOTE><CODE>
<PRE>
static define idle_host_callback ()
{
loop (Max_Num_Processes_Per_Host)
{
variable slave_argv = build_slave_argv (0);
pvm_ms_add_new_slave (slave_argv);
}
}
pvm_ms_set_idle_host_callback (&idle_host_callback);
</PRE>
</CODE></BLOCKQUOTE>
</P>
<DT><B> See Also </B><DD><P><CODE>
<A HREF="#pvm_ms_set_message_callback">pvm_ms_set_message_callback</A></CODE></P>
</DL>
</P>
<H2><A NAME="pvm_ms_set_hosts"></A> <A NAME="ss4.12">4.12</A> <A HREF="pvm.html#toc4.12"><B>pvm_ms_set_hosts</B></A>
</H2>
<P>
<DL>
<DT><B> Synopsis </B><DD><P>Set list of hosts to use</P>
<DT><B> Usage </B><DD><P><CODE>pvm_ms_set_hosts (String_Type hosts[])</CODE></P>
<DT><B> Description </B><DD><P>This function may be used to specify which hosts will be used
to perform distributed calculations. The default is to use
all hosts in the current PVM.</P>
<DT><B> Example </B><DD><P>
<BLOCKQUOTE><CODE>
<PRE>
pvm_ms_set_hosts (["vex", "pirx", "aluche"]);
</PRE>
</CODE></BLOCKQUOTE>
</P>
<DT><B> See Also </B><DD><P><CODE>
<A HREF="pvm-5.html#pvm_addhosts">pvm_addhosts</A></CODE></P>
</DL>
</P>
<HR>
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