Re: [lwip-users] How to avoid lwIP v2.1.2 udp send stuck when data is coming in faster than it is going out

[Lan Yang]

Hi Сергей Борщ,


I would like to explain my situation clearer. 

In the function udp_client_send() defined by me, I used mutex.

I called the udp_client_send() function separately in two threads in my RTOS.
Thread A runs every 1ms and calls the udp_client_send() function 100 times per run.
Thread A runs every 1s and calls the udp_client_send() function 100 times per run.
The length of data sent by UDP is 5000 bytes.

Because of the mutex, the program will only pbuf_alloc a new pbuf when the last pbuf is free.

The program is still stuck though I used mutex to make sure only one pbuf is allocated at one time.
The"assert stuck line: p!=NULL" is inside the pbuf_free() function.
You can see the assert line at this link:
https://github.com/RT-Thread/rt-thread/blob/a0ca06b4994d7c4a423b03f272c2c2a86a7bd07f/components/net/lwip/lwip-2.1.2/src/core/pbuf.c#L732
 

So the num of pbuf is enough, as I only used one pbuf at one udp_send(). 

Now I just don't know how this stuck problem is triggered, and I don't know how to solve it.

Do you have any new guesses or directions for experimentation?

С уважением,

Lan

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