close_session required?

[wollud1969]

Hi,

I'm using objects of the Client class together with a context manager to talk to an OpenPCS7 server:

while not stopped:
    async with Client(url=...) as client:
        for nodeSpec in nodes:
            try:
                node = client.get_node(nodeSpec)
                dataValue = await node.read_data_value()
                # do something use with the dataValue
            except ua.UaError as e:
                # more or less just log the caught exception
    await asyncio.sleep(period)

I've started with the "client minimal" example and introduce my own data handling.

My assumption is that using the context manager is enough for tidying up all used resources. However, occasionally - to be honest: quite often, I get BadTooManySessions errors from the server. Is it, beyond using the context manager, required to call activate_session and particularly close_session? Or is that, as I assume, done by the context manager for me? In that case I would reckon that the server is somehow to "small", that there are a couple of other clients and that it is not really my mistake to get this errors.

Thanks and cheers
Wolfgang

[swamper123]

First: I am not familiar with OpenPCS7 server.

The context manager calls aexit which should disconnects the Client. What I can't see is a

You may have to take a look what the server limits are...not sure how your setup is built atm.

[swamper123]

@wollud1969 Are any Exceptions thrown or errors logged, while closing the connection in normal cases?

[wollud1969]

No, there are no other exceptions. Suddenly the BadTooManySessions pops up.

[oroulet]

interesting issue. the context manager calls disconnect that calls close_session. So in theory the session is closed...

[wollud1969]

So, at least I'm on the right side when using the context manager and not closing the session explicitly. That's fine. Considering some other quite interesting behaviors of the OpenPCS7 server I would assume for the moment that it is not this library or my own code which is doing something wrong.

[swamper123]

In case to be 100% sure, you can trace the traffic via Wireshark and see, if everything is done as expected from Client side.