Situation:
Table LOCKTEST with unique field TESTID.

From one session (for example SQL+) insert a record with TESTID=33 without commit.

Then from Delphi application with thread having a TOracleQuery do the same (insert record with TESTID=33). Then this thread hangs until the other session is committed.

If you don't commit the other thread and call OracleSession.LogOff in the hanging thread the application wil crash without any exception! The last debug line is a call to 'OCISessionEnd'.

Calling BreakExecution first doesn't make a difference.

Any ideas?

If TOracleSession.ThreadSafe = False in a multi-threaded application, you must be careful when you access the same session from different threads. Simultaneous access can lead to unpredictable results.

If a thread is waiting for a lock, then you do not have much control. Like you said, BreakExecution does not help (the Oracle Server does not respond in case of a lock). You can only wait until the lock is released.

It's not the same session. The thread has its own TOracleSession. And what if the execution takes on for ever?? There must be a possibility to stop the execution.

I just use the thread to be able to access the oraclesession. If it is hanging in main thread, the application doesn't react at all.

So one session in a thread in a delphi application and the other session is through Oracle's SQL+.

The Oracle session in the thread has ThreadSafe=false because it isn't used by more threads.

I wrote a testproject:

Test Project

You must set the connection-info for the database and create the table as described in the top of unit1.pas.

You can add the record from SQL+ or with the button 'Add Record' that adds a record to the testtable. Then press the execute button, which inserts the same record in the same table with another session from a thread.

You cannot disconnect a session in the main thread that is currently executing in a background thread. All you can do is call TOracleSession.BreakExecution, and if that doesn't help, you have no real control over the session until execution finishes.

OK, but why does my application crash when I call logoff??? It doesn't even show an exception in Delphi!

This is caused by the Oracle Call Interface DLL (oci.dll). Like I said, you cannot access a session from 2 different threads if ThreadSafe is false, this will lead to unpredictable results.

Did you try my test project????
It uses 2 different sessions!!!
Then ThreadSafe isn't relevant according to your help:

Quote: "Multi-threaded, multi-session database access. No special properties need to be set, and session management is clear."

What am I missing??

I didn't notice that it uses multiple sessions. What exactly should I do in your application to reproduce the problem?