Logging assert failures in freeRTOS

Question

I am trying to use the NRF_LOG system with FreeRTOS. In the case of an ASSERT, I want to be able to: 
 1) log the location of the assertion 
 2) flush the logs over RTT 
 3) reset 
 
 The issue I'm seeing is that adding a flush to the ASSERT macro causes the worst case stack usage of all tasks to increase dramatically. Each stack now requires at lease 1000 bytes because the nrf_log_frontend needs ~300 bytes and nrf_log_backend_rtt_put requires ~700 bytes. 
 
 What method is recommended for avoiding this excessive stack usage? 
 
 Is there a way to trigger log flushing from the logger_thread instead of the current thread?

Anthony Ambuehl · Accepted Answer

The issue is that the ASSERT is called deep inside of API code instead of passing back error codes. Also since the ASSERT calls NRF_LOG_FLUSH() it actually requires additional stack space for the logging backend operation which is not reported by the static analysis since it is called from a function pointer. 
 The logger thread by itself does not fix this problem. However I have modified the example assert to eliminate the flush. My workaround is to set a flag in the assert and then raise the priority and resume the logger thread which will perform the flush.

Logging assert failures in freeRTOS

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