[lwip-users] memp_malloc: out of memory in pool TCP_PCB

[Anirudha Sarangi]

Hi,

Recently after fixing my previous issue (I had an issue in sys_arch.c), I came across one interesting issue for lwip140 which is not seen in lwip130.

 

I have a RTOS based application running and I have a small webserver application.

I saw that after refreshing the webpage several times on the host PC, I start getting messages:

 

memp_malloc: out of memory in pool TCP_PCB

 

Inspite of these messages webserver works. But these messages are really annoying and tell us that something horrible has happened.

 

I checked the memory pools. I have defined "MEMP_NUM_TCP_PCB as 64".

So precisely after around 64 http requests, I start getting the above message.

If I reduce MEMP_NUM_TCP_PCB to 32, I start getting the messages after around 32 refreshes.

 

Is it some kind of bug? Is there anything I should be doing while closing the socket each time other than calling lwip_close ?

 

 

regards

Anirudha

[Simon Goldschmidt]

Anirudha Sarangi <anirudha...@yahoo.com> wrote:

memp_malloc: out of memory in pool TCP_PCB

 

Inspite of these messages webserver works. But these messages are really annoying and tell us that something horrible has happened.

No, that's normal: you ran out of pcbs, but the tcp code then closes that oldest pcb in TIME-WAIT state and then calls memp_malloc again, which then succeeds. This is why the web server continues to run normally.

In tcp, pcbs stay in TME_WAIT state for some minutes, so you would have to configure the tcp pcb pool very large to get rid of this message.

Simon

[Anirudha Sarangi]

Thanks a lot for the clarification.

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