[DUG] Crystal Reports Crashing the App
Neven MacEwan
neven at mwk.co.nz
Fri Mar 30 13:47:09 NZST 2007
Rohit Gupta wrote:
"Hey Robert Zimmerman got a song for you, bout a young man called Dylan
with a voice like sand and glue"
Glad you found it (if you had)
N
> Are you talking about John B Murphy or Frank Zimmerman ?
>
> I think I have found the problem. It uses two callbacks from the
> crpe.ddl back to TCrpe component (to local nested procedures in each
> case).
> What amazes me is that works at all. It also explains why the app
> dies even when it is idle and finished doing the report many seconds
> ago. It is fiddling with data on the heap thats long gone.. and what
> about the stack frame ? Yeach !!
>
> We have just tried V11. Luckiliy the VCL changes are minor and the
> reports are working. Still have to look at its source and test the
> crash cases.
>
> Neven MacEwan wrote:
>> Rohit
>>
>> I think the crpe.dll was only written to be used by one app crpe.exe
>> and is very sequence fragile,
>> I know the guy that wrote the VCL for it had all sorts of problems,
>> I'd make sure you don't try to get it to do to many
>> things at the same time on the same instance
>>
>> HTH
>>
>> Neven
>>
>>> Robert,
>>>
>>> all this can not be correct. How can a DLL be written that will not
>>> work with more than one app at a time ? Especially when there are
>>> no common resources or files to use. The data space is mapped to
>>> the app that is using the dll.
>>>
>>> I have also discovered that the memory gets trashed asynchronously
>>> of report access. You can leave the app there and 10-30 seconds
>>> later it will suddenly complain with rubbish errors or just
>>> disappear. This is when no one has even touched the keyboard in
>>> that time.
>>>
>>>
>>> Robert martin wrote:
>>>> Hi
>>>>
>>>> Yes. But what bugs will they have introduced in the process?
>>>>
>>>> Don't know if two would work. I would guess yes.
>>>>
>>>> Rob Martin
>>>> Software Engineer
>>>>
>>>> phone +64 03 377 0495
>>>> fax +64 03 377 0496
>>>> web www.chreos.com
>>>>
>>>> Wild Software Ltd
>>>>
>>>>
>>>>
>>>> Rohit Gupta wrote:
>>>>> I see that BO are saying the the crpe is now threadsafe in v11.
>>>>> Do I believe them ?
>>>>>
>>>>> Question - do you know if it two crpe components are allowed in
>>>>> the same app ? We use one to interrogate the report for formulas
>>>>> etc and the other is bound to a form for running the report.
>>>>>
>>>>> Robert martin wrote:
>>>>>> Hi Rohit
>>>>>>
>>>>>> It has been some time since I used the Crpe method of accessing
>>>>>> Crystal but my understanding is it is not Thread safe and
>>>>>> therefore if you use it in threads or try running multiple copies
>>>>>> of reports it can go bang. This may be what you are experiencing.
>>>>>>
>>>>>> In the end w gave up on Crpe and now use the Com object to run
>>>>>> them. This works better but comes with other issues. I think it
>>>>>> is the better access method though.
>>>>>>
>>>>>> Not a log of help i'm afraid :)
>>>>>>
>>>>>> Rob Martin
>>>>>> Software Engineer
>>>>>>
>>>>>> phone +64 03 377 0495
>>>>>> fax +64 03 377 0496
>>>>>> web www.chreos.com
>>>>>>
>>>>>> Wild Software Ltd
>>>>>>
>>>>>>
>>>>>>
>>>>>> Rohit Gupta wrote:
>>>>>>> In our real app, the program crashes randomly (regularly for
>>>>>>> some users) at the instance that Crpe is used. The app
>>>>>>> basically disappears which implies that substantial code and/or
>>>>>>> stack is corrupted.
>>>>>>>
>>>>>>> In a smaller app that only opens the report to get some stats
>>>>>>> (it does not connect to the database), I can get it to crash in
>>>>>>> the same fashion predictably.
>>>>>>>
>>>>>>> The sequence of events is open two copies of the app )or one
>>>>>>> copy of the app and the CRW designer)
>>>>>>> Open any report in the first app (which always assignes
>>>>>>> ReportName to blank and does not destroy the crpe component
>>>>>>> Open any report in the second app or CRW Designer
>>>>>>> Open any report in the first app and its gone with no trace.
>>>>>>>
>>>>>>> In real life the users can not run multiple copies, the app
>>>>>>> takes care of that. However the symptoms are identical leading
>>>>>>> me to believe that if I can find the cause of the second crash,
>>>>>>> I can fix the first one.
>>>>>>>
>>>>>>> Any clues anyone ?
>>>>>>> I cant find anything pertinent on google, except for one item
>>>>>>> where the author insists that the problem is a secret com object
>>>>>>> that crpe launches and if you wait for it to finish and
>>>>>>> terminate then there are no crashes. However, delays dont have
>>>>>>> any effect on my test case.
>>>>>>>
>>>>>>> In the debugger, if I keep doing F7, everything keeps working.
>>>>>>> But as soon as I press F8 or F9, it gets an AV because it starts
>>>>>>> executing in hyperspace.
>>>>>>>
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>>>>>>
>>>>>
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>>>>
>>>
>>> --
>>> *Rohit Gupta*
>>> * B.E. Elec. M.E. Mem IEEE Associate IEE*
>>> *Technical Manager*
>>> *Computer Fanatics Limited*
>>> ** *Tel* +64 9 4892280
>>> *Fax* +64 9 4892290
>>> *Email *rohit at cfl.co.nz <mailto:rohit at cfl.co.nz>**
>>> *Web *www.cfl.co.nz <http://www.cfl.co.nz/>
>>>
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>>
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>>
>
> --
> *Rohit Gupta*
> * B.E. Elec. M.E. Mem IEEE Associate IEE*
> *Technical Manager*
> *Computer Fanatics Limited*
> **
> *Tel* +64 9 4892280
> *Fax* +64 9 4892290
> *Email *rohit at cfl.co.nz <mailto:rohit at cfl.co.nz>**
> *Web *www.cfl.co.nz <http://www.cfl.co.nz/>
>
> ------------------------------------------------------------------------
> This email and any attachments contain information, which is
> confidential and may be subject to legal privilege and copyright. If
> you are not the intended recipient, you must not use, distribute or
> copy this email or attachments. If you have received this in error,
> please notify us immediately by return email and then delete this
> email and any attachments.
> ------------------------------------------------------------------------
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> Delphi at ns3.123.net.nz
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