How many connections can accept a 'binded' socket?

[billiejoex]

Hi,
I'm writing a small asyncore-based server application serving a lot of
clients. When I have to handle more than 1021 client simoultaneously
the 'binded' socket object raises an error:

[...]
connections: 1018
connections: 1019
connections: 1020
connections: 1021
Traceback (most recent call last):
File "asyncore_clien t.py", line 31, in <module>
File "asyncore.p y", line 191, in loop
File "asyncore.p y", line 138, in poll
File "asyncore.p y", line 80, in write
File "asyncore.p y", line 76, in write
File "asyncore.p y", line 395, in handle_write_ev ent
File "asyncore_clien t.py", line 24, in handle_connect
File "asyncore_clien t.py", line 9, in __init__
File "asyncore.p y", line 257, in create_socket
File "socket.py" , line 156, in __init__
socket.error: (24, 'Too many open files')

I just wanna know: is there a way to know how many connections can
accept a 'binded' socket BEFORE getting such error? Maybe
socket.SOMAXCON N could help me?

Thanks in advance.

[Laurent Pointal]

Re: How many connections can accept a 'binded' socket?

billiejoex a écrit :

Hi,
I'm writing a small asyncore-based server application serving a lot of
clients. When I have to handle more than 1021 client simoultaneously
the 'binded' socket object raises an error:
>
[...]
connections: 1018
connections: 1019
connections: 1020
connections: 1021
Traceback (most recent call last):
File "asyncore_clien t.py", line 31, in <module>
File "asyncore.p y", line 191, in loop
File "asyncore.p y", line 138, in poll
File "asyncore.p y", line 80, in write
File "asyncore.p y", line 76, in write
File "asyncore.p y", line 395, in handle_write_ev ent
File "asyncore_clien t.py", line 24, in handle_connect
File "asyncore_clien t.py", line 9, in __init__
File "asyncore.p y", line 257, in create_socket
File "socket.py" , line 156, in __init__
socket.error: (24, 'Too many open files')
>
I just wanna know: is there a way to know how many connections can
accept a 'binded' socket BEFORE getting such error? Maybe
socket.SOMAXCON N could help me?

Here you get out of file descriptors, I dont think SOMAXCONN would help.

Under Linux (maybe Unix), there is ulimit -n nnn to setup the maximum
number of files descriptors. I don't know its upper limit (maybe a
kernel compile time information).

[Alex Martelli]

Re: How many connections can accept a 'binded' socket?

Laurent Pointal <laurent.pointa l@limsi.frwrote :

billiejoex a écrit :

Hi,
I'm writing a small asyncore-based server application serving a lot of
clients. When I have to handle more than 1021 client simoultaneously
the 'binded' socket object raises an error:

[...]
connections: 1018
connections: 1019
connections: 1020
connections: 1021
Traceback (most recent call last):
File "asyncore_clien t.py", line 31, in <module>
File "asyncore.p y", line 191, in loop
File "asyncore.p y", line 138, in poll
File "asyncore.p y", line 80, in write
File "asyncore.p y", line 76, in write
File "asyncore.p y", line 395, in handle_write_ev ent
File "asyncore_clien t.py", line 24, in handle_connect
File "asyncore_clien t.py", line 9, in __init__
File "asyncore.p y", line 257, in create_socket
File "socket.py" , line 156, in __init__
socket.error: (24, 'Too many open files')

I just wanna know: is there a way to know how many connections can
accept a 'binded' socket BEFORE getting such error? Maybe
socket.SOMAXCON N could help me?

>
Here you get out of file descriptors, I dont think SOMAXCONN would help.
>
Under Linux (maybe Unix), there is ulimit -n nnn to setup the maximum
number of files descriptors. I don't know its upper limit (maybe a
kernel compile time information).

A shell command

ulimit -Hn

should report on the hard-limit of the number of open file descriptors;
just ulimit -n should report on the current soft-limit.

If you're going to pass the fd's to select, as asyncore does by default,
a separate limit of 1024 is unfortunately likely to apply anyway; so,
once that ulimit is raised, you may want to pass argument use_poll as
true to asyncore.loop. The performance of poll with a huge number of
sockets may however not be all that shiny. Better mechanisms, such as
epoll or kqueue, I believe, are not available for asyncore, even if your
OS supports them; to serve thousands of open sockets with good
performance, you may need to switch to Twisted (which offers many more
implementations of the abstract Reactor interface -- you don't _have_ to
use Twisted's higher layers if you don't want to).


Alex

[John Nagle]

Re: How many connections can accept a 'binded' socket?

billiejoex wrote:

Hi,
I'm writing a small asyncore-based server application serving a lot of
clients. When I have to handle more than 1021 client simoultaneously
the 'binded' socket object raises an error:

When you ask questions like this, please specify what
operating system you're using. Thanks.

John Nagle

[billiejoex]

Re: How many connections can accept a 'binded' socket?

On 20 Mar, 17:44, John Nagle <n...@animats.c omwrote:

When you ask questions like this, please specify what
operating system you're using. Thanks.

That was a Linux Ubuntu 6.10. I submitted a bug report on sourceforge:

http://sourceforge.net/tracker/index.php?func=detail&aid=1685000&group_id=5470&atid=105470

Alex Martelli wrote:

A shell command
ulimit -Hn
should report on the hard-limit of the number of open file descriptors;
just ulimit -n should report on the current soft-limit.

Thank you, I'll try it.