Channel max part2

[baelter]

WHAT is this pull request doing?

Was i little trigger happy with the prio PR....

• Improving channel_max specs
• Actually implementing channel_max 0 = unlimited

Question: How do we handle the "hard" limit of UInt16::MAX?
Should we communicate that? Or have it as a "hidden" limit?

HOW can this pull request be tested?

Specs

[spuun]

Question: How do we handle the "hard" limit of UInt16::MAX?
Should we communicate that? Or have it as a "hidden" limit?

It's probably insane to open more than (or even close to) UInt16::MAX, but the spec allows it. I guess it would be good to support real unlimited.

[baelter]

real unlimited

Well, that is not possible. There is a limit to how many electrons there are in the universe. Or maybe not. But a limit to how many we have access to :)

[spuun]

With channel_max = 0 in config:

# lavinmqperf connection-count -x 1 -c 100000 --uri 'amqp://guest:guest@localhost/%2F?channel_max=0' 
Unhandled exception in spawn: channel_max reached (Exception)

[baelter]

channel_max reached

UInt16::MAX = 65535 so it's expected. And that error is coming from amqp-client, but if it would not lavinmq would also stop at 65535 and close the connection.

Do we want channel ids to be UInt32 instead?

[baelter]

Actually 0 is not "unlimited" it's

Zero indicates no specified limit.

And channel ids are short i.e uint16 per definition. So theoretical max is 65535. In RabbitMQ as well.

[spuun]

channel_max reached

UInt16::MAX = 65535 so it's expected. And that error is coming from amqp-client, but if it would not lavinmq would also stop at 65535 and close the connection.

Do we want channel ids to be UInt32 instead?

I was confused by the commit message Implement channel_max 0 = unlimited. But "unlimited" can't exist since channel id is a "short" (uint16), so unlimited means UInt16::MAX.

[spuun]

Actually 0 is not "unlimited" it's

Zero indicates no specified limit.

And channel ids are short i.e uint16 per definition. So theoretical max is 65535. In RabbitMQ as well.

Oh, didn't update before i wrote my last comment! 👍