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BSD send() => BSD_ENOMEM

Galuski

Hi,

I'm actually implementing a webserver with multiple threads and sockets listening to port 80.

The MDK is version 5.29.

Assuming the BSD send() can be called from different threads for different sockets, I don't understand the return value BSD_ENOMEM, which I sometimes get.

All these error return values are not really described in detail. "Not enough memory" for BSD_ENOMEM is not really helpful.

  • Which memory got low?
    I tried to play with the Ethernet core memory (NET_MEM_POOL_SIZE), the heap and all involved stack sizes of the KEIL driver.
    No luck. Can't get rid of this error.

It does not happen very often. Let's say 1 out of 5000 send() calls.

It happens in blocking & non-blocking mode.

Any help is appreciated.

Michael

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  • +1

    "Not enough memory" means the available memory in the memory pool got low.

    There is only one memory pool used in the Network component. It is configured with NET_MEM_POOL_SIZE macro. Default value is 12000 bytes.

    Try to double the pool size to 24000 bytes or more.

    Check also the thread priorities of your socket threads. The priorities should be the same as the priority of the Network Core thread, which is osPriorityNormal by default.

    If you still get this error, add osThreadYield() after each BSD send(). Maybe sending large data blocks fills the dynamic memory, before the Network Core thread gets a chance to process TCP ACKs. Stream sockets keep a shadow copy of the data being sent for a possible retransmission. Received ACKs then release the data from the shadow copy, thus freeing the memory pool.

    You might also try to send the data in smaller data blocks, or add a short osDelay() after BSD send()..

    Take a look at the select() function. It allows you to run your WEB server from a single thread only.

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  • +1

    "Not enough memory" means the available memory in the memory pool got low.

    There is only one memory pool used in the Network component. It is configured with NET_MEM_POOL_SIZE macro. Default value is 12000 bytes.

    Try to double the pool size to 24000 bytes or more.

    Check also the thread priorities of your socket threads. The priorities should be the same as the priority of the Network Core thread, which is osPriorityNormal by default.

    If you still get this error, add osThreadYield() after each BSD send(). Maybe sending large data blocks fills the dynamic memory, before the Network Core thread gets a chance to process TCP ACKs. Stream sockets keep a shadow copy of the data being sent for a possible retransmission. Received ACKs then release the data from the shadow copy, thus freeing the memory pool.

    You might also try to send the data in smaller data blocks, or add a short osDelay() after BSD send()..

    Take a look at the select() function. It allows you to run your WEB server from a single thread only.

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