[PD-dev] [tcpserver]: bad performance of new version

Martin Peach martin.peach at sympatico.ca
Thu Apr 30 16:17:43 CEST 2009

Roman Haefeli wrote:
> i ve been testing the new netpd-server based on the new
> [tcpserver]/[tcsocketserver FUDI] now for a while and definitely could
> solve some problems, but some new ones were introduced. 
> i found, that the most recent version of [tcpserver] peforms quite bad
> cpu-wise. this has some side-effects. in netpd, when a certain number of
> users are logged in (let's say 16), it can happen, that the traffic of
> those clients makes the netpd-server use more than the available
> cpu-time. i made some tests and checked, if all messages come through
> and if messages delivered by the server are still intact. under normal
> circumstances, there is no problem at all. but under heavy load, when
> the pd process is demanding more than available cpu time, some messages
> are corrupted or lost completely; in the worst case the pd process
> segfaults, at the moment of  a client connecting or disconnecting. i
> guess, this is due to some buffer under- or overrun between pd and the
> tcp stack, but i don't really know.

Hi Roman,
Did you try using the new [timeout( message? The latest version of 
tcpserver defaults to a 1ms timeout, so if you have a bunch if 
disconnected clients, Pd will hang for 1ms each, which will quickly add 
up to more than the audio block time and then Pd will start thrashing 
and eventually die or become comatose, as it were.
I think you need to experiment with different values for the timeout. 
Set it to zero and it should give the same results as the previous 
version; maybe try something around 100 instead of the default 1000 
(it's in microseconds).
The other way to fix this in the tcpserver source is to make a new 
thread for each client, but I'm afraid that will just open another can 
of worms/zombies.


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