App timer list gets corrupted with SDK 13 -> Dead lock

RE: App timer list gets corrupted with SDK 13 -> Dead lock

TomKeddie — Mon, 27 May 2019 17:11:57 GMT

I'm seeing something similar in app_timer2 see details at devzone.nordicsemi.com/.../app_timer2-timer-list-corruption-seen-on-rtc-overflow

RE: App timer list gets corrupted with SDK 13 -> Dead lock

2PrintBeta — Fri, 29 Mar 2019 15:08:42 GMT

I just changed my application to handle those timeouts differently which prevents this problem.

Instead of starting and stopping the timers, i use a faster repeating timer and check variables to see if a command timedout. This completely prevents the problem and is a workung workaround for us.

Nevertheless the underlying problem still persists and might cause serious issues for other users.

RE: App timer list gets corrupted with SDK 13 -> Dead lock

2PrintBeta — Fri, 29 Mar 2019 10:34:50 GMT

Hi,

I am not sure i understand correctly.

To clarify what my application does:

My application currently sends some request over ble to another device. And it starts an app_timer to handle the timeout of this request. If the answer to this request arrives in time,the timer is stopped. If it does not, the timer handler gets called, which might place a new request and create another timeout timer. The timers are all single-shot.

Do you mean i should only start/stop the timers from the main loop via the app_scheduler ? Sounds very compilcated and might seriously change the timing if the system is loaded.

Do you have an example ?

RE: App timer list gets corrupted with SDK 13 -> Dead lock

Jørgen Holmefjord — Fri, 29 Mar 2019 09:57:00 GMT

Hi,

I see that we have an internal report of a similar issue that have not yet been resolved. A workaround that have been mentioned is to use app_scheduler for the timer tasks, could you see if that solves your issue?

Best regards,
Jørgen

RE: App timer list gets corrupted with SDK 13 -> Dead lock

mrono — Fri, 29 Mar 2019 07:28:09 GMT

This sounds similar to the issue I was having here.

What I learned was that re-starting an app_timer that is already running might cause the code to hang. My fix was to add a check to app_timer_start if the app_timer instance is already running.

I haven't checked SDK 15.3, but this one isn't fixed in 15.2 or earlier.