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digitalmars.D.learn - Waiting for a Spawn'ed process

reply "Sharad Gupta" <gsharad007 yahoo.com> writes:
I am trying to make a Utility which spwans=>pipeShell off 
multiple processes on user choice.

On of the issues is that some process need to wait for other 
processes to finish. Now I could implement it using messages but 
that doesn't seem very nice solution. I could also wait for the 
pipeShell pid but was wondering what is the standard or 
recommended way to wait on a spawned process?
Mar 28 2014
parent reply "Vladimir Panteleev" <vladimir thecybershadow.net> writes:
On Friday, 28 March 2014 at 15:52:17 UTC, Sharad Gupta wrote:

 I am trying to make a Utility which spwans=>pipeShell off 
 multiple processes on user choice.

 On of the issues is that some process need to wait for other 
 processes to finish. Now I could implement it using messages 
 but that doesn't seem very nice solution. I could also wait for 
 the pipeShell pid but was wondering what is the standard or 
 recommended way to wait on a spawned process?


Calling wait on the Pid object returned by std.process functions 
is the standard way to wait for a process to finish in D.
Mar 28 2014
parent reply "Sharad Gupta" <gsharad007 yahoo.com> writes:
On Friday, 28 March 2014 at 16:37:00 UTC, Vladimir Panteleev 
wrote:

 On Friday, 28 March 2014 at 15:52:17 UTC, Sharad Gupta wrote:

 I am trying to make a Utility which spwans=>pipeShell off 
 multiple processes on user choice.

 On of the issues is that some process need to wait for other 
 processes to finish. Now I could implement it using messages 
 but that doesn't seem very nice solution. I could also wait 
 for the pipeShell pid but was wondering what is the standard 
 or recommended way to wait on a spawned process?


 Calling wait on the Pid object returned by std.process 
 functions is the standard way to wait for a process to finish 
 in D.


But I don't have a Pid object but instead have Tid object from 
the spawn function in std.concurrency lib.
Mar 28 2014
parent reply =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 03/28/2014 10:19 AM, Sharad Gupta wrote:

 On Friday, 28 March 2014 at 16:37:00 UTC, Vladimir Panteleev wrote:

 On Friday, 28 March 2014 at 15:52:17 UTC, Sharad Gupta wrote:

 I am trying to make a Utility which spwans=>pipeShell off multiple
 processes on user choice.

 On of the issues is that some process need to wait for other
 processes to finish. Now I could implement it using messages but that
 doesn't seem very nice solution. I could also wait for the pipeShell
 pid but was wondering what is the standard or recommended way to wait
 on a spawned process?


 Calling wait on the Pid object returned by std.process functions is
 the standard way to wait for a process to finish in D.


 But I don't have a Pid object but instead have Tid object from the spawn
 function in std.concurrency lib.


If you start the worker with spawnLinked then you will receive a 
LinkTerminated message.

import std.stdio;
import std.concurrency;
import core.thread;

void main()
{
     auto worker = spawnLinked(&workerFunc);

     // Wait for worker to terminate
     bool terminated = false;
     while (!terminated) {
         writeln("Waiting for the worker to terminate...");

         terminated = receiveTimeout(1.seconds,
             (LinkTerminated e) {
                 if (e.tid == worker) {
                     writefln("Terminated");
                 }
             }
         );
     }
}

void workerFunc()
{
     Thread.sleep(3.seconds);
}

Ali
Mar 28 2014
parent reply "Sharad Gupta" <gsharad007 yahoo.com> writes:
 If you start the worker with spawnLinked then you will receive 
 a LinkTerminated message.

 import std.stdio;
 import std.concurrency;
 import core.thread;

 void main()
 {
     auto worker = spawnLinked(&workerFunc);

     // Wait for worker to terminate
     bool terminated = false;
     while (!terminated) {
         writeln("Waiting for the worker to terminate...");

         terminated = receiveTimeout(1.seconds,
             (LinkTerminated e) {
                 if (e.tid == worker) {
                     writefln("Terminated");
                 }
             }
         );
     }
 }

 void workerFunc()
 {
     Thread.sleep(3.seconds);
 }

 Ali


But this is another spawned process. How can I tell this second 
process to wait on the first one.

eg:

auto processA = spawnLinked(funcA);
auto processB = spawnLinked(funcB);

funcA()
{
   doSomething();
}

funcB()
{
   doSomething();
   // wait for A
   doSomethingElse();
}

This is a simplified example, the real case two process would be 
spawned irrespective to each other. the second process could may 
also be launched by when the first is already done.
Mar 28 2014
parent =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 03/28/2014 11:43 AM, Sharad Gupta wrote:


 But this is another spawned process. How can I tell this second process
 to wait on the first one.


std.concurrency is based on message passing. Normally, the second 
process would send a message either to its owner or to another thread 
that was previously register()'ed.

If message passing does not work for you then you may need to use 
lower-level modules like core.thread.

Ali
Mar 28 2014