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

[Roman Haefeli]

On Thu, 2009-04-30 at 10:17 -0400, Martin Peach wrote:
> 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.

no, i haven't tried this parameter yet. but i sure will do and report
back, when i can tell more about how it behaves. 

i haven't fully understood, what it does and what it can be used for.
could you elaborate that a bit more? yet it sounds a bit strange to me,
that i need to tweak a networking object with a time value for correct
operation.


> I think you need to experiment with different values for the timeout.

ok

>  
> Set it to zero and it should give the same results as the previous 
> version;

you, mean, [tcpserver] will hang pd, when the buffer of a certain socket
is full? or do you mean the version, that cut off some parts of messages
under certain circumstances?

>  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.

i hardly know anything about threading, but i guess that is what other
servers do (e.g apache). also didn't i see a way around creating
dynamically an instance of the protocol handling abstraction for each
socket, which is, i guess, something similar to threading in the pd
world (not technically, but conceptually). 

roman


	
		
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