From: Deadolus <deadolus@...>
Date: 2008-01-19T03:54:59+09:00
Subject: Re: Start a program, get it's output, then kill it. while 	"multithreading"...

On 18 Jan., 11:56, Robert Klemme <shortcut...@googlemail.com> wrote:
> 2008/1/18, Deadolus <deado...@gmail.com>:
>
>
>
> > i'd like to program a gui for iperf (http://sourceforge.net/projects/
> > iperf), it should run under windows And *NIX and I'm using fox as my
> > gui toolkit, I'll use some extra calculations to get the parameters,
> > that's why I can't use an already existing gui for iperf.
> > I already designed the gui and I'm now moving to connect the different
> > widgets to it's functions.
> > After you set all your parameters (size of packet, bandwith,
> > time, ...) I want to press a button and it should start iperf and
> > parallely read the it's output, so I can display some statistics
> > (running time and, on server side, the packet loss, maybe more).
> > So what should I program to do this?
> > I read about multithreading, IO.popen would be perfect, but how can I
> > kill iperf when I want to quit, before iperf ran out of time?
> > I think threads could also work (especially because one can kill
> > threads, if no longer used so the program would be terminated), but
> > what do I do to start the iperf?
>
> First of all killing a thread won't help because the process is in no
> way attached to a Ruby thread (btw, this would also be true if Ruby
> was using native threads).
>
> You can however use a thread to read output from IO.popen.  For
> example, you could stuff lines into a Queue which is read from your UI
> thread and displayed.  Or whatever you want do do with it.
>
> About the killing I am not sure.  With a quick check I did not find a
> proper way to get the PID of the child process with IO.popen.  If
> there is no way you could use popen with "-" as command (i.e. start a
> child process), have that writ out the current PID (in $$) to stdout
> and exec the process you want to start.  The parent would then have to
> read the child PID first and remember it somewhere.
>
> Kind regards
>
> robert
>
> --
> use.inject do |as, often| as.you_can - without end

I think I found the solution, this is a example script:

io = IO.popen("ping google.ch") #open a new io
thread = Thread.new(io) {while !io.closed? do Thread.current["line"] =
io.readline end}#ALWAYS read current line of io
i=0 #example code...
while i<10 do
puts thread["line"]
puts thread.status #puts out "sleep", so it's running...
i+=1
sleep(1)
end
io.close #close io
thread.status #puts out "nil" so it's terminated

Seems like you easily can close a io just by "close".
At least it isn't in my ps aux list any more...
But I just tested under linux so far, so I can't say if this also
works under windows (I currently have some problems with my windows
box).
What do you think about this solution?
If anyone has a better solution, I'm still interested....