[fpc-pascal] Stuck in TMSSQLConnection.Execute

[Luca Olivetti]

El 6/5/26 a les 12:02, Luca Olivetti via fpc-pascal ha escrit:


Since I don't manage the ms sql server, don't know what it does in its 
stored procedures and views and don't want to learn the intricacies of 
its transaction management, I just added a TCriticalSection so that only 
one connection can start a transaction (they should complete quite fast 
anyway).
Maybe there's a way to achieve the same with some special parameter in 
the transaction/connection but the global TCriticalSection works.

Bye


> El 6/5/26 a les 10:55, Luca Olivetti via fpc-pascal ha escrit:
> 
> As always I found the problem right after hitting "send": another thread 
> started a transaction which blocks this one.
> I still don't understand why (this is a select that it shouldn't be 
> affected by the other transaction)
> 
> Bye
> 
>> Hello,
>>
>> I encountered a strange problem in an application, that's been running 
>> for over a year now.
>> The application is quite convoluted with hundred of threads, one 
>> (actually more than one) of those threads connects to an ms sql server 
>> and now it blocks inside TMSSQLConnection.Execute, but not always
>>
>>
>> procedure TMSSQLConnection.Execute(const cmd: string);
>> begin
>>    DBErrorStr:='';
>>    DBMsgStr  :='';
>>    CheckError( dbcmd(FDBProc, PAnsiChar(cmd)) );
>>    CheckError( dbsqlexec(FDBProc) );  <--- this doesn't return
>>    CheckError( dbresults(FDBProc) );
>> end;
>>
>>
>> However when I terminate the application and before the destroy method 
>> of the thread is called, dbsqlexec returns and the rest of the thread 
>> goes on as nothing happened.
>>
>> As an experiment I wrapped the method in synchronize but that only 
>> freezes the gui when it happens.
>>
>> I don't know it if is relevant but I have a note in my program that I 
>> have to initialize the sql server libraries in the main thread, 
>> otherwise doing it in another thread eventually causes a sigsev.
>>
>> I got the dlls (almost 2 years ago) following the instructions here
>>
>> https://forum.lazarus.freepascal.org/index.php/ 
>> topic,55037.msg409167.html#msg409167
>>
>> using Environment: PLAT=Win32, WIDTH=32, VS_VERSION=2017, TDSVER=7.3
>> (though older artifacts are deleted after a month)
>>
>> This is on windows 32 bits, fpc 3.2.2, any hint on how to debug it 
>> further?
>>
>> Bye
> 
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