On Thu, 7 Oct 2021, Bo Berglund via fpc-pascal wrote:
On Tue, 5 Oct 2021 10:22:44 +0200 (CEST), Michael Van Canneyt via fpc-pascal
<fpc-pascal@lists.freepascal.org> wrote:
My program in Lazarus *is* a "simple program" and it has no GUI components.
I never even looked at the implementation of CheckSynchronize()...
It was just given in another thread when I was working on the port from Delphi
to Linux and thus from the Windows GUI environment to the non-GUI command line
program environment.
The name 'Gui thread' is misleading. It's simply the main program thread.
If you want to use TThread.Synchronize then the call to CheckSynchronize is
needed. The LCL for GUI application simply calls it automatically for you.
In a non-GUI command-line program, you're responsible for calling it from
time to time.
That is what I had learned back in beginning of this year when I was starting
testing on actual hardware. Checksynchronize is needed in the main program loop
in order for threads to fire off events etc. I use threads to handle serial port
communications, and the threads should be disposed of after use...
Now I have done some more investigations and I am more confused by it...
My service program runs at about 4% CPU usage as shown by top. This holds true
for a long time after starting it (several idle days).
But when a client connects to inspect data on the system the usage spikes when
he commands some data display etc. But then goes back to the 4% or so.
If the client enables a task to be executed then nothing really happens until
that task starts on its set time.
At that time the CPU usage raises from 4% to 11% and goes up/down a few % for
the minutes it runs and then returns to an idle value of about 8%, which it
never gets below after that.
No matter how long I wait it is now stuck at that double value.
So clearly something must be left behind after the task has finished...
The question is: how to find what is still using CPU?
Run the process under strace:
strace -f -p PID -o log1.txt
with PID the process ID.
You will see what system calls are executed. Do this when the load is 4% and
when it's 8%, maybe this will tell you something.
Michael.
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