Linit the number of external process running at any one time

[Jeff]

I need to run many processes from my application. and I am using the
following enclosed in a for next loop:

System.Diagnostics.Process runObj = new System.Diagnostics.Process();
runObj.StartInfo.FileName = exepath;
runObj.Start();

What I want to do is limit the number of of process which are run at any
one time. So if I have 20 processes to run I can limit it to 10
consecutive processes. When a process finishes the next in the list
starts untill all process finish.

How could I achieve this using this code or is there a better way of
doing this.

Regards
Jeff

[Marc Gravell]

Sounds like a semaphore might be the simplest answer:

Semaphore count = new Semaphore(5, 5);
for (int i = 0; i < 20; i++)
{
count.WaitOne();
ThreadPool.QueueUserWorkItem(state =>
{
Process.Start("notepad.exe").WaitForExit();
count.Release();
});
}

I tried to use the Exited event (rather than ThreadPool), but it didn't
seem to raise...

Marc

[Peter Duniho]

On Thu, 18 Sep 2008 05:02:03 -0700, Marc Gravell <ma**********@gmail.com>
wrote:

[...]
I tried to use the Exited event (rather than ThreadPool), but it didn't
seem to raise...

It won't, unless you set the Process.EnableRaisingEvents property to
true. It's false by default.

Pete

[Marc Gravell]

d'oh! Cheers Pete - I was having a slow moment ;-p

[Peter Duniho]

On Thu, 18 Sep 2008 14:42:56 -0700, Marc Gravell <ma**********@gmail.com>
wrote:

d'oh! Cheers Pete - I was having a slow moment ;-p

Well, so far I think I've still had more "slow moments" than you. So
you're ahead of the game. :)

[Marc Gravell]

For the OP's benefit - the same without the ThreadStart would be:

Semaphore count = new Semaphore(5, 5);
for (int i = 0; i < 20; i++)
{
count.WaitOne();

Process proc = new Process();
proc.StartInfo = new ProcessStartInfo("notepad.exe");
proc.EnableRaisingEvents = true;
proc.Exited += delegate
{
count.Release();
proc.Dispose();
};
proc.Start();
}

Obviously you might be picking successive commands out of an array /
list, rather than using "notepad.exe" each time ;-p

Marc