Re: A Very Troubled Application...

Mike, this is indeed a component, and not a standalone application?
if so did you try the ThreadException as Peter mentioned?

On Wed, Jun 10, 2009 at 1:26 PM, Mike Andrews
<[email protected]>wrote:

> Yes, I'd be curious as well as to how the system cleans up after a fault.
>  I
> know yesterday when I intentionally caused the app to crash numerous times
> my system (Windows XP Pro) became unstable in that Explorer would just
> randomly "hang" and not let you utilize the task bar; it was ridiculous.
>
> I have a similar situation that I'm working on where instead of using Word
> I'm using some other 3rd party app that behaves very poorly but the issue
> is
> moot since I must use it and must adapt it to be a "server"
> non-user-monitored application.  I'm well on my way to it and I've done a
> majority of the work but solving cases where the application just fails is
> a
> very difficult endeavor.
>
> On Wed, Jun 10, 2009 at 11:22 AM, Adam Tuliper <[email protected]
> >wrote:
>
> > we had to do the same hacks for word.. using it as server side doc
> > generation before good pdf components were available to us and I recall
> > word
> > would fail after a while. that goodness we've come a long way  : )
> >
> > For dlls being cleaned at termination time.. library code segments are
> > shared between processes (that reference the same lib). So there is only
> > one
> > code section in memory (unless specifically designated otherwise I
> > believe).
> > When LoadLibrary is called, ref count is incremented. So when a process
> > crashes.. how does the system know what to decrement counts for? I don't
> > believe it does.. and hence a potential memory issue with crashed
> > appliations leaving resources around.  If I'm not 100% correct on this..
> I
> > would like to know a reference to how the system cleans up.. Id be
> curious
> > of the inner workings, this is all from rusty memory.
> >
> >
> >
> >
> >
> > On Wed, Jun 10, 2009 at 2:01 AM, Peter vd Weerd <[email protected]>
> wrote:
> >
> > > When windows terminates a process, all system-resources are cleaned up.
> > > Dll's too. They are loaded in the virtual address space, and the
> address
> > > space is removed at termination.
> > > Reference counting on dll's is only within a process. AFAIK there is no
> > > system-wide refcnt.
> > >
> > > Dll's are loaded by creating a named filemapping to this dll. This
> > mapping
> > > is a normal system resource and will be freed at termination time.
> > >
> > > Out of process COM objects are a different story. The process where
> this
> > > COM-object lives has nothing to do with the hosting process (as far as
> > the
> > > system knowns). And it is refcnted.
> > >
> > > So if the host process is getting terminated, the only way for the COM
> > > process to get auto terminated is to do a watchdog check on its host if
> > its
> > > still alive. There are some watchdog checks in the standard marshalling
> > code
> > > (hartbeats), but I'm not sure if they are used for terminating the
> > process
> > > with the COM object. Another question is how big the timeout for this
> > > watchdog is. So may be you want to restart the COM object before the
> > > watchdog timed out.
> > >
> > > I used my proposed solution (restarting the process after failure) a
> few
> > > times in case of untrusted applications, and it worked fine. I can
> > remember
> > > problems with MSWord (out of process COM) years ago. After failure (the
> > > process using MSWord died) I killed the MSWord instance too and than
> > > restarted my application. Ugly, but it worked.
> > > I had more problems there, because word was not designed as a service.
> > Its
> > > a UI, so it will popup a dialog every now and than. I had to 'answer'
> > those
> > > dialogs too :-)
> > >
> > > /Peter
> > > ----- Original Message ----- From: "Adam Tuliper" <
> > [email protected]>
> > > To: <[email protected]>
> > > Sent: Tuesday, June 09, 2009 10:30 PM
> > > Subject: Re: [ADVANCED-DOTNET] A Very Troubled Application...
> > >
> > >
> > >
> > >  I seem to recall the opposite was true.. Windows isn't very good about
> > >> cleaning up resources (at least in the past) because of the way
> > libraries
> > >> dont get freed because the reference count handling is never
> executed..
> > >> something along those lines. Although if someone can provide some more
> > >> technical reference on if this is true or not.. Id love to read it.
> > >>
> > >>
> > >>
> > >> On Tue, Jun 9, 2009 at 1:00 PM, Peter vd Weerd <[email protected]>
> > wrote:
> > >>
> > >>  Mike,
> > >>>
> > >>> In general: if you have access violations caused by COM-components,
> its
> > >>> not
> > >>> a good idea to recover from that.
> > >>> If you can isolate the complete application to a kind of a
> > >>> worker-process,
> > >>> you write a controller-program that starts this worker-process, and
> if
> > it
> > >>> fails, just start a new one.
> > >>>
> > >>> Windows is very good in recovering from crashed processes: all
> > resources
> > >>> are freed. So, when the controller process fires up a new
> > worker-process
> > >>> its
> > >>> a brand new one with clean memory, a clean .NET virtual machine, etc.
> > >>>
> > >>> /Peter
> > >>>
> > >>>
> > >>> ----- Original Message ----- From: "Mike Andrews" <
> > >>> [email protected]>
> > >>> To: <[email protected]>
> > >>> Sent: Tuesday, June 09, 2009 6:06 PM
> > >>> Subject: [ADVANCED-DOTNET] A Very Troubled Application...
> > >>>
> > >>>
> > >>>
> > >>> I have a very troubled application (not mine but a 3rd party) that
> > likes
> > >>> to
> > >>>
> > >>>> fail with various Unhandled exceptions (memory access and others)
> when
> > >>>> certain files are loaded (I have no idea of the reason).  Sometimes
> > >>>> loading
> > >>>> a file causes a COM exception to occur (no one knows why and it's
> very
> > >>>> unlikely that the manufacturer will ever fix it).  This causes the
> > >>>> entire
> > >>>> application to crash (and/or provide some other unpredictable
> > behavior).
> > >>>> This does not occur most of the time but only occasionally.  However
> I
> > >>>> must
> > >>>> account for these eventualities as this process will be running on
> > >>>> multiple
> > >>>> servers and I need it the most stable I can get it.
> > >>>>
> > >>>> What I have been doing is looking for the process in the process
> list
> > >>>> and
> > >>>> then killing it.  That works most of the time but when one of those
> > >>>> dialogs
> > >>>> is thrown up asking you to click OK it really messes things up.
>  I've
> > >>>> started looking for the dialog, but the time when the dialog appears
> > >>>> varies
> > >>>> so any predictability is out.
> > >>>>
> > >>>> What I need to know is if it's possible to attach a hook (or some
> > other
> > >>>> such
> > >>>> mechanism) to the window to intercept any unhandled win32 exceptions
> > >>>> similar
> > >>>> to the capability available in the .NET framework.  I'm at my wit's
> > end
> > >>>> here
> > >>>> on this one.  I need to create something stable enough so I can
> > recover
> > >>>> on
> > >>>> the server and continue.
> > >>>>
> > >>>> Any help or information would be most appreciated.
> > >>>>
> > >>>> Thanks,
> > >>>> Mike
> > >>>>
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