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Steve Tuckner 08-08-2003 05:27 PM

Catching thread exceptions
 
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Recently I was helping a colleague who was new to Ruby with a program
that was using threads. It seemed to him that for some reason that some
of the thread's were not running. First he tried adding sleeps to the
main thread to "give time" to the other threads to run, but this didn't
work. It turns out that by joining the threads in question, that there
were errors in the program that were throwing exceptions that killed the
thread -- SILENTLY.

I don't know if there is a better way to do this, but this is the
solution we came up with to print out any exceptions that occur in a
thread (uncaught) and exit the program.

require "thread"

class MyThread < Thread
def initialize(*args, &block)
super(*args) do
begin
block.call
rescue Exception => e
$stderr.print "Exception occured: #{e.message} at " +
e.backtrace.join("\n")
exit! 1
end
end
end
end

Is there a better way?

Steve Tuckner

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<BODY>
<DIV><FONT face=3DArial size=3D2><SPAN =
class=3D009342117-08082003>Recently I was=20
helping a colleague who was new to Ruby with a program that was using =
threads.=20
It seemed to him that for some reason that some of&nbsp;the thread's =
were not=20
running. First he tried adding sleeps to the main thread to "give time" =
to the=20
other threads to run, but this didn't work. It turns out that by =
joining the=20
threads in question, that there were errors in the program that were =
throwing=20
exceptions that killed the thread -- SILENTLY.</SPAN></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><SPAN=20
class=3D009342117-08082003></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2><SPAN class=3D009342117-08082003>I =
don't know if=20
there is a better way to do this, but this is the solution we came up =
with to=20
print out any exceptions that occur in a thread (uncaught) and exit the =

program.</SPAN></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><SPAN=20
class=3D009342117-08082003></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2><SPAN =
class=3D009342117-08082003>require=20
"thread"</SPAN></FONT></DIV>
<DIV>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2><SPAN class=3D009342117-08082003>class =
MyThread &lt;=20
Thread<BR>&nbsp;def initialize(*args, =
&amp;block)<BR>&nbsp;&nbsp;super(*args)=20
do<BR>&nbsp;&nbsp;&nbsp;begin<BR>&nbsp;&nbsp;&nbsp ;&nbsp;block.call<BR>&=
nbsp;&nbsp;&nbsp;rescue=20
Exception =3D&gt; e<BR>&nbsp;&nbsp;&nbsp;&nbsp;$stderr.print "Exception =
occured:=20
#{e.message} at " + =
e.backtrace.join("\n")<BR>&nbsp;&nbsp;&nbsp;&nbsp; exit!=20
1<BR>&nbsp;&nbsp;&nbsp;end<BR>&nbsp;&nbsp;end<BR>& nbsp;end<BR>end</SPAN>=
</FONT></DIV>
<DIV><FONT face=3DArial size=3D2><SPAN=20
class=3D009342117-08082003></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2><SPAN class=3D009342117-08082003>Is =
there a better=20
way?</SPAN></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><SPAN=20
class=3D009342117-08082003></SPAN></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2><SPAN class=3D009342117-08082003>Steve =

Tuckner</SPAN></FONT></DIV></BODY></HTML>

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ts 08-08-2003 05:34 PM

Re: Catching thread exceptions
 
>>>>> "S" == Steve Tuckner <STUCKNER@MULTITECH.COM> writes:

S> Is there a better way?

Thread.abort_on_exception = true

svg% ruby -e 'Thread.new { raise "aa" }; p "after"'
"after"
svg%

svg% ruby -e 'Thread.abort_on_exception = true; Thread.new { raise "aa" }; p "after"'
-e:1: aa (RuntimeError)
from -e:1:in `initialize'
from -e:1:in `new'
from -e:1
svg%


Guy Decoux


Brian Candler 08-08-2003 05:56 PM

Re: Catching thread exceptions
 
On Sat, Aug 09, 2003 at 02:34:48AM +0900, ts wrote:
> >>>>> "S" == Steve Tuckner <STUCKNER@MULTITECH.COM> writes:

>
> S> Is there a better way?
>
> Thread.abort_on_exception = true


described at
http://www.rubycentral.com/book/tut_threads.html
and
http://www.rubycentral.com/book/ref_...t_on_exception

Regards,

Brian.



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