BUG: SocketBufferSize is only 64k by default + SocketBufferSize.Max != net.core.rmem_default

[andreas-h-sie]

Describe the issue:

We experience a lot of grab failures even at moderate data rate. It turned out that even setting net.core.rmem_default and net.core.rmem_max does not change the SocketBufferSize of 64k.

grab_params = camera.GetStreamGrabberNodeMap()
                    if grab_params is not None:
                        node = grab_params.GetNode("SocketBufferSize")
                        old_val = node.GetValue()
                        max_val = node.GetMax()
                        node.SetValue(max_val)
                        logger.info(f"Stream SocketBufferSize (KB): {old_val} -> {node.GetValue()} (max={max_val})")

gives

INFO - Stream SocketBufferSize (KB): 64 -> 64 (max=64)

However

        with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as s:
            s.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, 2**30)
            effective = s.getsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF)
            # kernel doubles the requested value, so effective == 2 * rmem_max
            # we return the raw value to request (rmem_max), kernel will double it again
            rmem_max = effective // 2
            logger.info(f"Probed rmem_max={rmem_max} (kernel reported {effective})")
            return rmem_max

gives

 Probed rmem_max=33554432 (kernel reported 67108864)

Also with ss I confirmed that the pylon socket is only created with 64k buffer size. Manually overriding the socketbuffer (via /proc/self/fd) to larger size solves the problem and the grab fails go away.

I believe it is a pylon bug that the receive socket buffer size is only 64k. Also that the SocketBufferSize.Max is only 64k and not the net.core.rmem_max is also a bug.
Even though I have to admit that the value of net.core.rmem_max is not available inside of a container. However one can probe the kernel indirectly for rmem_max by just opening a socket with a super large buffer request (see above).

Reproduce the code example:

grab_params = camera.GetStreamGrabberNodeMap()
if grab_params is not None:
                        node = grab_params.GetNode("SocketBufferSize")
                        old_val = node.GetValue()
                        max_val = node.GetMax()
                        node.SetValue(max_val)
                        logger.info(f"Stream SocketBufferSize (KB): {old_val} -> {node.GetValue()} (max={max_val})")

Error message:

Is your camera operational in Basler pylon viewer on your platform

Yes

Hardware setup & camera model(s) used

python3 -c "from pypylon import pylon; print(pylon.GetPylonVersion())"
[11, 3, 0, 928]

Runtime information:

Python 3.11.6 (main, Nov 29 2023, 04:47:02) [GCC 10.2.1 20210110] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys, pypylon.pylon, platform
>>> print(f'python: {sys.version}')
python: 3.11.6 (main, Nov 29 2023, 04:47:02) [GCC 10.2.1 20210110]
>>> print(f'platform: {sys.platform}/{platform.machine()}/{platform.release()}')
platform: linux/x86_64/6.1.111-cip29-rt15+ind1
>>> print(f'pypylon: {pypylon.pylon.__version__} / {".".join([str(i) for i in pypylon.pylon.GetPylonVersion()])}')
pypylon: 26.02.1 / 11.3.0.928