[DUG] Program crashes - anyone knows why?

[Matthew Comb]

Have you made the insertion into the TListView threadsafe? e.g.
Synchronized or similar ?

Matt.

> They display the information in a TListView set to Report style. When a
> keyword is processed it is added to the list. There shouldn't be problems
> with this, I've previously worked on an application that processed 60.000
> keywords and there was no problem (though there was only 1 thread there).
>
> Csaba
>
>
> On Sun, 26 Nov 2006 21:26:34 +0100, Matthew Comb <matt at ferndigital.com>
> wrote:
>
>> I would be more concerned with what the threads do with the information
>> they get once completed searching.
>>
>> e.g. displaying on main form in some way.
>>
>> Exceptions within a thread shouldn't propogate to the main thread unless
>> im missing something?
>>
>> Matt.
>>
>>> Thanks Conor, I've added (A) and sent the application to the client, so
>>> let's hope there will be some progress.
>>>
>>>
>>> On Sun, 26 Nov 2006 20:35:38 +0100, Conor Boyd
>>> <Conor.Boyd at trimble.co.nz>
>>> wrote:
>>>
>>>> That's a very detailed email... ;-)
>>>>
>>>> Without delving deeper, I've a couple of comments/suggestions.
>>>>
>>>> A) You definitely need a try-except block in your Execute method.  You
>>>> must not let unhandled exceptions propagate out of a thread.  Even if
>>>> you only put a call to OutputDebugString in your exception handler,
>>>> then
>>>> that means you could use e.g. DebugView from Sysinternals to view
>>>> exceptions being thrown.
>>>>
>>>> B) Try adding the madExcept library from www.madshi.net to your
>>>> application.  It should help hugely in tracking down unhandled errors
>>>> like this, especially when they are happening on a remote machine.
>>>> You
>>>> can configure it so that in the event of an error, your program can
>>>> automatically email you the error reports including call stacks, etc.
>>>>
>>>> C) You could also try using the URLDownloadToFile function from the
>>>> URLMon unit instead.  I use it in a threaded application, and it works
>>>> fine for me.
>>>>
>>>> I don't know what you're using to access Google, but I've been using
>>>> the
>>>> Indy components very successfully in one of my projects.
>>>>
>>>> Good luck in trying your error down...
>>>>
>>>> HTH,
>>>>
>>>> Conor
>>>>
>>>> -----Original Message-----
>>>> From: delphi-bounces at ns3.123.co.nz
>>>> [mailto:delphi-bounces at ns3.123.co.nz]
>>>> On Behalf Of Gajo Csaba
>>>>
>>>> I wrote a multithreaded application for a client and it crashes on the
>>>> client's computer, while it works ok on mine. Can someone give me a
>>>> clue
>>>> as to what might be the problem?
>>>>
>>>> The program works like this: I have two TThreadLists: one contains a
>>>> list of keywords (~20000) while the other a list of proxy servers
>>>> (~500). When the user clicks on the button, 21 threads are created. 1
>>>> thread directly accesses Google, enters the keyword and processes the
>>>> result. The other 20 threads do the same, except they use a proxy
>>>> server.
>>>>
>>>> OK, so each thread grabs a keyword from the list and then removes it
>>>> from the list, so no one else could use it again. It tries to access
>>>> the
>>>> internet. If the connection fails then it means the proxy doesn't
>>>> work,
>>>> so it gets another proxy address from the list. No two threads ever
>>>> share the same proxy. If there are no more free proxies left, the
>>>> thread
>>>> dies (and returns the unprocessed keyword to the list).
>>>>
>>>> [snip]
>>>>
>>>> _______________________________________________
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>>>> Delphi at ns3.123.co.nz
>>>> http://ns3.123.co.nz/mailman/listinfo/delphi
>>>>
>>>>
>>>
>>>
>>>
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>>
>>
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