On 1 Jan, 10:21 am, tobias.oberst...@tavendo.de wrote:
Hi,
I am doing network performance tests using netperf on a trivial Twisted
TCP echo server (code at the end).
One of the tests that netperf offers is throughput, and I am running
into an issue with this.
? [snip]
Now, my suspicion is that Twisted is reading off the TCP stack from the
kernel and buffering in userspace faster than the echo server is
pushing out stuff to the TCP stack into the kernel. Hence, no TCP
backpressure results, netperf happily sends more and more, and the
memory of the Twisted process runs away.
What you said here about "buffering in userspace" is ambiguous. It's
not clear if you meant data is being buffered in userspace on the read
side before your protocol gets a chance to handle it or if you meant
that data being written to the transport by the protocol is being
buffered in userspace.
The former doesn't happen. There are no no userspace read buffers in
Twisted between the transport and the protocol. Bytes are read from the
socket and then passed to dataReceived.
The latter would be addressed by using producer/consumer APIs as Glyph
suggested.
Jean-Paul
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