WDT on repetitive connection when distant server is slow to free conn or respond

[me-no-dev]

WDT on repetitive connection when distant server is slow to free conn or respond

[me-no-dev]

it's not purely AsyncTCP that does this. Your ESP is too busy to have spare cycles to run the idle task for 5 seconds. I could introduce maybe artificial delay in the task somehow....

[jc999]

hmm .. but the esp are running fine if I run only 2 or 3 of them... when using all of them (same binary code... ) the problems start. the esp is not doing more stuff when running alone or with a lot of other esp... (1 udp broadcast received in sync/loop, 1 tcp sent to the broadcaster with async).
which could mean that some network task are taking too long, depending on the external http server. Thus, in this case ( in case of it's linked), a timeout could be a solution to kill the conn...

[iafilius]

A few questions/tips to look into:

regarding webserver:
The java webserver isn’t esp32, just random webserver?
Are tcp sessions nicely closed after each request? Or do you keep it (until session cache timeout?)
Whats does netstat -anp say on webserver.
Is it somehow predictable?
doing a 16x simultanous connect to one service may/will hit the tcp backlog queue/mechanism.
Having a tcp backlog setting lower then the simultanous requests will keep the other clients waiting, by not sending a response.
Depending on TCP stack settings the SYN-retry may be 3 seconds or so.
If the/your code operates in blocking mode at this point it is easy to get the WDT triggered.
I'm curious to have a look at:
tcpdump/capture of the traffic, and a pointer to the exact time to look at.
netstat -anp during the issue, and when it just runs fine.

Can you share the actual code (server + ESP32)? so we can have a more close look?
Wdt mask’s the issue, i would suggest to disable it for debugging purposes and see what your issue really is.

In case not into the tcp backlog mechanism, a linkk which i thing desribes it quite in depth.
http://veithen.io/2014/01/01/how-tcp-backlog-works-in-linux.html

it is not completely clear to me from where watchDogAsync is called, and if you use custom watchdog or asynctcp's buildin.

Regards,

Arjan

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