Ping request not sent under heavy load?

[jhoughjr]

Moving the discussion here.

A summary;
My setup is Mosquitto on macOS as the broker.
iOS client using MQTTNIO and a C++ client running on wio terminal.

The WIO publishes 3 topic of 1-3 bytes each set to every ten µs.
From the Mosquitto logs that rate does not appear to be making it through.

After about 500 messages on each topic, the iOS client disconnects.
searches for PINGREQ show only the wio terminal client.

I'll XP by reducing the interval the WIO sends at.

[jhoughjr]

Im also looking for a breakpoint when the ping req is sent as I seem to have found the code.

[jhoughjr]

else block 68-70 of PingreqHandler was reached . the condition self.lastEventTime + self.timeout <= .now() was false

[adam-fowler]

Jimmy is this with iOS 15 beta
I've been running the subscribe on the iOS 14 emulator for the last 10 minutes
I'll setup an iOS project and run it on my phone

[jhoughjr]

still no ping messages logged in Mosquitto. Im going to try and slow the wio publish down. (been trying for realtime visualization :) )

[jhoughjr]

I still dont think the ping is even being sent rather than it failing. Still digging. Ill make a repo for this so you can see the code. Something might pop out.

[adam-fowler]

Looking through the code it only will ever send a ping if the connection is inactive. I have seen a possible bug though. I reset the timer on both read and write of messages when this should only ever be on write.

Are your messages being sent with QoS 0 (.atMostOnce)?

[adam-fowler]

If this is the case, you should try the 1.x.x branch which has a fix for this

[adam-fowler]

@jhoughjr did the 1.x.x branch fix your issue