Problem after sending a few MQTT messages with FreeRTOS and LwIP on STM32F406VGTX

[lealoureiro]

Hi Guys,

I would check if someone could help me here with a small projecting I'm trying to build.

I have project that sends MQTT (from LwIP) messages periodically using 3 CMSISv2 tasks (i send them with different time intervals, some with 1s and others with 5s).

The messages have approximately the following sizes: 9, 58 and 362 chars.

After sending some of them, all of them stop being sent :(

The piece of code where the code seems to occur is in the LwIP libraries, mqtt.c:

 r = mqtt_create_request(client->req_list, LWIP_ARRAYSIZE(client->req_list), pkt_id, cb, arg);
 if (r == NULL) {
 return ERR_MEM;
 }

I tried to disable the task that sends the biggest message and seems to work fine (didn't tested for more than 1/2 hours)

I also added a Mutex to make sure only one task at time is sending a message (not sure if it helps).

Some more info regarding the configuration configure in CubeMX:

Thread Stack Sizes: 2048

FreeRTOS Heap Size: 30760

LwIP MEM SIZE: 16360.

Not sure what other values could be relevant to try help solve the problem.

Thanks in advance,

Leandro

[Tesla DeLorean]

So does it fail with a memory error?

Do you have a resource leak when it comes to freeing memory, or double-freeing resources?

Check exit/failure paths.

Perhap wrap the heap allocation/release to monitor for issues there.

Track who is allocating the memory. Match the release of each.

Build something to walk the heap looking for orphans or fragmentation issues.

[lealoureiro]

Yeaps, when the problem starts occurring the if condition evaluates to true.

I think I need to debug a bit more but LwIP code is very complex.

How can i know which version of the LwIP CubeMX uses? Is the latest?

[lealoureiro]

I think i fixed the problem by increasing the priority of the thread task that sends the bigger message and increasing the RING size (MQTT_REQ_MAX_IN_FLIGHT) from 4 to 10.

At least after 2 hours still sending messages normally.