invalid channel: 0 error

[luca-iachini]

Hello,
first of all, thanks for the great library.
sometimes, I receive Invalid channel: 0 when I publish a message on a queue, do you know why that happens?
The following is the piece of code that raises the error:

fn send_message(msg: &[u8]) -> Result<()> {
        let conn = Connection::connect(&addr, ConnectionProperties::default()).await?;
        let channel = conn.create_channel().await?;
        channel
            .basic_publish(
                "",
                "messages",
                BasicPublishOptions::default(),
                msg,
                BasicProperties::default(),
            )
            .await?;
       Ok(())
}

That function opens a new connection, creates a channel, and sends a message on every invocation.
When I see that error, the client sent the message successfully, so it does not impact the normal flow of the application.
I guess that the client receives messages from the server after it dropped channel 0.

Any help would be very appreciated.

[Keruspe]

That’s interesting. My guess is the same as yours.
Any reason why you’re not reusing the connection and/or channel out of curiosity?

[luca-iachini]

That example is taken from a test. it occurs more frequently in cases where the connection is dropped immediately after usage.

[Keruspe]

Right!
Minimal reproducers are indeed always greatly appreciated.
You might be in luck as I might have time to debug this tonight.
Would you happen to have a test account on a server where you can reproduce it? It sometimes can depend on the server and/or network route leading to it.

[luca-iachini]

sorry, I don't have a test account to share. Good to know that you have time to debug it 😃

[oliverbrowneprima]

Hey @Keruspe, after a little digging (I work with @luca-iachini, for reference), I have a question about the logic of Channels::set_connection_closed - it drains the channels map, sending an internal rpc RemoveChannel command for each found channel, which results in a call to Channels::remove, which tries to remove the channel from the channels internal map... which has just been drained?

Isn't that a double-remove? I know I must be missing something, since this error isn't perfectly reproducible?

EDIT: whoops, looks like you beat me too it 😄. Thanks!

[Keruspe]

It doesn’t send a RemoveChannel IPC there btw

[oliverbrowneprima]

Channel::set_closed calls InternalRPCHandle::remove_channel no?

Sorry I'm purely satisfying my curiosity here, to be clear.

[Keruspe]

You are absolutely right.
Just did some more tests and we can simplify all of this!

[oliverbrowneprima]

You are absolutely right. Just did some more tests and we can simplify all of this!

Wooo! 🥳