I have a multi threaded program which executes a list of tasks in real time. It is difficult to debug with a debugger on this program (since debugging will pause the execution which will be messy for this application).

So, I log the exceptions to a log file and I found this exception: EPrivilege Privileged instruction

What could possibly raise this exception?

My program is win 32 from Lazarus 1.7 FPC 3.1.1
and running on Win 7 64 bit.

thanks in advance.

Dennis

A couple of ideas (no more than this)

1. A corrupt stack has resulted in a function return address being corrupted and the program jumps to an illegal instruction.

2. Executing data (shouldn't really happen).

3. Corrupt VMT sgain resulting in the program jumping to an illegal instruction.

The problem with these type of bugs is that cause and effect can be some way apart. I tend to debug multi-threaded programs that are mis-behaving by having lots of writeln statements and then looking at the output log to see which patterns of behaviour lead to the problem. Can be an art rather than a science.

Your not using teventobject in your threads are you? There is a bug in the RTL which could cause weird issues with threads if you are using teventobject.create.

I don't use TEventObject (because I don't know how to use it). I have my internal task queue that my worker thread loop through the task queue.
The exception was raised within one of the many tasks in the task queue.

Dennis

If you can, change the app so that it'll also output what parameters and calls are being passed in as well. Drop in a debug statement or two on entrance and exit to any and all functions within the thread. Then keep an eye on the logs.

Check this thread on Stack Overflow;

http://stackoverflow.com/questions/89607/what-is-a-privileged-instruction