[erlang-questions] stress test with tcp_server

Oscar Hellström <>
Mon Jul 2 13:03:30 CEST 2007


Hi

Gaspar Chilingarov wrote:
> Jeremy Chow wrote:
>> I've tried use command ulimit to increase the file descriptors number to
>> 10240.
>> but the connections number was no more than 1024, sometimes is 1017,
>> sometimes is 1018.
> 
> it depends how much files descriptors already allocated by this user at
> the moment -- because file descriptor limit is set for users and not for
> 1 process.
> 
> Anyway, after some experiments with FreeBSD I was able to push max
> connection count to 4999 open connections
> 
> You should tune sysctl's to increase a hard limits
>   kern.maxfiles: 25000
>   kern.maxfilesperproc: 20000
> 
> I've also tried to increase kern.ipc.nmbclusters=64000 but without success.
> 
> Are there any limit in 5000 FD's hard coded in erlang???

No, but if I remember correctly FreeBSD also has a setting for max 
sockets per process, not only FD's (this could be another BSD though). 
Also, depending on the application the maximum number of processes (+P) 
can affect the situation.

$ sysctl -a | grep max might give hints :)

I've had over 20000 connections without problems using FreeBSD.

> Setting ERL_MAX_PORTS also does not change the situation.
> 
> /Gaspar
> 

Best Regards
-- 
Oscar Hellström, 
Erlang Training and Consulting
http://www.erlang-consulting.com/



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