DSF-API pydsfapi and CPU utilization on RPi during print

resam

I'm running all the latest stable releases:
RRF 3.2.2, DSF 3.2.2, DSF-APIs/pydsfapi 3.1.3
on a Raspberry Pi 3B+.

I'm running a simply Python app to intercept M7000 and take a webcam photo during a layer change - so only once every few minutes:

intercept_connection = pydsfapi.InterceptConnection(InterceptionMode.PRE)
intercept_connection.connect()
while True:
    cde = intercept_connection.receive_code()
    if cde.type == code.CodeType.MCode and cde.majorNumber == 7000:
        success = intercept_connection.flush(cde.channel)
        if not success:
            log_print("Flush failed")
            intercept_connection.cancel_code()
            continue
        take_camera_snapshot()
        intercept_connection.resolve_code()
    else:
        intercept_connection.ignore_code()

While printing, I observe that this python process is essentially pegging a whole CPU core: almost or even slightly more than 100% in htop.

The /opt/dsf/bin/DuetControlServer process is hovering around 10-15% of CPU (when looking at htop)

My total system memory with an print job:

$ free -h
              total        used        free      shared  buff/cache   available
Mem:          924Mi       172Mi       548Mi       6.0Mi       203Mi       693Mi
Swap:            0B          0B          0B

Is this a bottleneck that could affect print performance?
How does DSF/DCS behave if one of the IPC clients cannot keep up, @chrishamm?

Am I using it wrong, @wilriker?

Would the Go-based API be more performant and should be preferred over Python?

resam

Of course as luck will have it, I cannot reproduce it anymore.
So take my report from above as tainted - might have been a race condition or something else. ¯_(ツ)_/¯

wilriker

@resam Whatever it was, you can also avoid high load when using pydsfapi 3.2.0 or later by making use of the filters parameter when instantiating Intercept_connection. It takes a list of strings specifying those codes you are interested in. DSF will then only forward these codes to your client.

I have modified your new code example to show how to use it.