Re: [tcljava-user] How to kill a jacl thread

[Bruce J. <nm...@ma...>]

One approach I use in applications using Swank is whenever I do  
something that will take a long time, but might need to be cancelled  
is to use the following procs (which can be cleaned up a bit, but  
basically work).  Before starting the "job" I call NvCounterMake, then  
within the long running job periodically call NvCounterCheck.  Every  
time it is called it will update a counter that is displayed (hence  
the name for the procs) and check the status of a global variable  
named "int_flag".  Pushing the Quit button will set the int_flag.  In  
the implementation below the NvCounterCheck proc will throw an error  
if int_flag is set.  There are more graceful ways to exit, but this is  
probably safer than just blowing away a Thread.  Obviously this won't  
work if your not working in Swank, but the general principle holds  
that Threads shouldn't be killed, some flag should be set so they know  
to gracefully exit.

Bruce



proc NvCounterMake {title} {
     global Nv_Priv
     set pwin .vecGraph.processor.border
     if {[winfo exists $pwin]} {
         set cwin $pwin.nvCounter
         set top 0
     } else {
         set top  1
         set cwin .nvCounter
     }
     global int_flag NvCounter
     set int_flag 0
     if {[winfo exists $cwin] } {destroy $cwin}
     if {$top} {
         toplevel $cwin
         wm withdraw $cwin
         wm title $cwin $title
         set x [expr [winfo screenwidth .]/2]
         set y [expr [winfo screenheight .]/4]
     } else {
         frame $cwin
         pack $cwin -side left
     }

     label $cwin.lab -textvariable NvCounter1 -width 10
     pack $cwin.lab -side left
     button $cwin.quit -text Quit -command "set int_flag 1;destroy  
$cwin"
     pack $cwin.quit -side right

     if {$top} {
         wm deiconify $cwin
         wm geometry $cwin 200x20+$x+$y
         wm alwaysontop $cwin 1
         raise $cwin
     }
     set Nv_Priv(counterWin) $cwin
     set NvCounter 1
     update
}
######################################################################

proc NvCounterCheck {} {
     global NvCounter NvCounter1 int_flag
     incr NvCounter
     set NvCounter1 $NvCounter
     if {($NvCounter % 200) == 0} {
         update
     }
     if {$int_flag} {
         NvCounterDestroy
         error "Interrupted"
         #return -code break
     }
}

proc NvCounterDestroy {} {
     global Nv_Priv int_flag
     catch "destroy $Nv_Priv(counterWin)"
     catch {after cancel $Nv_Priv(afterCounter)}
}


On Jan 29, 2009, at 11:29 AM, Jared Hodge wrote:

> Is there a good way to kill a jacl thread quickly from another  
> thread?  I’m launching a large script and that has many calls to  
> custom java code (some of which take a while themselves), and  
> sometimes I want to just kill the whole thread off and start another  
> one.  The problem is that the doOneEvent call seems to not exit  
> until the script is complete and so I can’t find a good way of  
> getting the run thread to exit.  It seems that all other ways of  
> exiting a thread have been deprecated.  Ideally I’d like to stop the  
> thread dead in its tracks in the middle of a java call, but that’s  
> probably beyond the scope of this mailing list.  A reasonable  
> alternative is to stop between evaluations in the jacl interpreter,  
> but I need some sort of low-level hook inside the doOneEvent call.   
> Does this already exist?
>
> Thanks
> -Jared
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