From: Avdi Grimm <avdi@...>
Date: 2013-09-29T18:34:06-04:00
Subject: [ruby-core:57468] Re: [ruby-trunk - Feature #6647] Exceptions raised in threads should be logged

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This would indeed eliminate a huge amount of confusion for people getting
started with threads. Or for people years of experience with threads, for
that matter...


On Fri, Sep 27, 2013 at 7:18 AM, headius (Charles Nutter) <
headius@headius.com> wrote:

>
> Issue #6647 has been updated by headius (Charles Nutter).
>
>
> So, can we do this for 2.1? I have heard from many other users that really
> would like exceptions bubbling out of threads to be reported in some way.
> We have had numerous bug reports relating to code where threads disappear
> without a trace.
> ----------------------------------------
> Feature #6647: Exceptions raised in threads should be logged
> https://bugs.ruby-lang.org/issues/6647#change-42043
>
> Author: headius (Charles Nutter)
> Status: Assigned
> Priority: Normal
> Assignee: matz (Yukihiro Matsumoto)
> Category: core
> Target version: next minor
>
>
> Many applications and users I have dealt with have run into bugs due to
> Ruby's behavior of quietly swallowing exceptions raised in threads. I
> believe this is a bug, and threads should always at least log exceptions
> that bubble all the way out and terminate them.
>
> The implementation should be simple, but I'm not yet familiar enough with
> the MRI codebase to provide a patch. The exception logging should be logged
> in the same way top-level exceptions get logged, but perhaps with
> information about the thread that was terminated because of the exception.
>
> Here is a monkey patch that simulates what I'm hoping to achieve with this
> bug:
>
>
> class << Thread
>   alias old_new new
>
>   def new(*args, &block)
>     old_new(*args) do |*bargs|
>       begin
>         block.call(*bargs)
>       rescue Exception => e
>         raise if Thread.abort_on_exception ||
> Thread.current.abort_on_exception
>         puts "Thread for block #{block.inspect} terminated with exception:
> #{e.message}"
>         puts e.backtrace.map {|line| "  #{line}"}
>       end
>     end
>   end
> end
>
> Thread.new { 1 / 0 }.join
> puts "After thread"
>
> __END__
>
> Output:
>
> system ~/projects/jruby $ ruby thread_error.rb
> Thread for block #<Proc:0x000000010d008a80@thread_error.rb:17> terminated
> with exception: divided by 0
>   thread_error.rb:17:in `/'
>   thread_error.rb:17
>   thread_error.rb:7:in `call'
>   thread_error.rb:7:in `new'
>   thread_error.rb:5:in `initialize'
>   thread_error.rb:5:in `old_new'
>   thread_error.rb:5:in `new'
>   thread_error.rb:17
> After thread
>
>
>
> --
> http://bugs.ruby-lang.org/
>



-- 
Avdi Grimm
http://avdi.org

I only check email twice a day. to reach me sooner, go to
http://awayfind.com/avdi

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<div dir=3D"ltr">This would indeed eliminate a huge amount of confusion for=
 people getting started with threads. Or for people years of experience wit=
h threads, for that matter...<br></div><div class=3D"gmail_extra"><br><br><=
div class=3D"gmail_quote">

On Fri, Sep 27, 2013 at 7:18 AM, headius (Charles Nutter) <span dir=3D"ltr"=
>&lt;<a href=3D"mailto:headius@headius.com" target=3D"_blank">headius@headi=
us.com</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quote" style=3D"=
margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">

<br>
Issue #6647 has been updated by headius (Charles Nutter).<br>
<br>
<br>
So, can we do this for 2.1? I have heard from many other users that really =
would like exceptions bubbling out of threads to be reported in some way. W=
e have had numerous bug reports relating to code where threads disappear wi=
thout a trace.<br>


----------------------------------------<br>
Feature #6647: Exceptions raised in threads should be logged<br>
<a href=3D"https://bugs.ruby-lang.org/issues/6647#change-42043" target=3D"_=
blank">https://bugs.ruby-lang.org/issues/6647#change-42043</a><br>
<br>
Author: headius (Charles Nutter)<br>
Status: Assigned<br>
Priority: Normal<br>
Assignee: matz (Yukihiro Matsumoto)<br>
Category: core<br>
Target version: next minor<br>
<br>
<br>
Many applications and users I have dealt with have run into bugs due to Rub=
y&#39;s behavior of quietly swallowing exceptions raised in threads. I beli=
eve this is a bug, and threads should always at least log exceptions that b=
ubble all the way out and terminate them.<br>


<br>
The implementation should be simple, but I&#39;m not yet familiar enough wi=
th the MRI codebase to provide a patch. The exception logging should be log=
ged in the same way top-level exceptions get logged, but perhaps with infor=
mation about the thread that was terminated because of the exception.<br>


<br>
Here is a monkey patch that simulates what I&#39;m hoping to achieve with t=
his bug:<br>
<br>
<br>
class &lt;&lt; Thread<br>
=A0 alias old_new new<br>
<br>
=A0 def new(*args, &amp;block)<br>
=A0 =A0 old_new(*args) do |*bargs|<br>
=A0 =A0 =A0 begin<br>
=A0 =A0 =A0 =A0 block.call(*bargs)<br>
=A0 =A0 =A0 rescue Exception =3D&gt; e<br>
=A0 =A0 =A0 =A0 raise if Thread.abort_on_exception || Thread.current.abort_=
on_exception<br>
=A0 =A0 =A0 =A0 puts &quot;Thread for block #{block.inspect} terminated wit=
h exception: #{e.message}&quot;<br>
=A0 =A0 =A0 =A0 puts e.backtrace.map {|line| &quot; =A0#{line}&quot;}<br>
=A0 =A0 =A0 end<br>
=A0 =A0 end<br>
=A0 end<br>
end<br>
<br>
Thread.new { 1 / 0 }.join<br>
puts &quot;After thread&quot;<br>
<br>
__END__<br>
<br>
Output:<br>
<br>
system ~/projects/jruby $ ruby thread_error.rb<br>
Thread for block #&lt;Proc:0x000000010d008a80@thread_error.rb:17&gt; termin=
ated with exception: divided by 0<br>
=A0 thread_error.rb:17:in `/&#39;<br>
=A0 thread_error.rb:17<br>
=A0 thread_error.rb:7:in `call&#39;<br>
=A0 thread_error.rb:7:in `new&#39;<br>
=A0 thread_error.rb:5:in `initialize&#39;<br>
=A0 thread_error.rb:5:in `old_new&#39;<br>
=A0 thread_error.rb:5:in `new&#39;<br>
=A0 thread_error.rb:17<br>
After thread<br>
<span class=3D"HOEnZb"><font color=3D"#888888"><br>
<br>
<br>
--<br>
<a href=3D"http://bugs.ruby-lang.org/" target=3D"_blank">http://bugs.ruby-l=
ang.org/</a><br>
</font></span></blockquote></div><br><br clear=3D"all"><div><br></div>-- <b=
r>Avdi Grimm<br><a href=3D"http://avdi.org" target=3D"_blank">http://avdi.o=
rg</a><br><br>I only check email twice a day. to reach me sooner, go to <a =
href=3D"http://awayfind.com/avdi" target=3D"_blank">http://awayfind.com/avd=
i</a>
</div>

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