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_client.py", line 31, in <module>
File "asyncore.py", line 191, in loop
File "asyncore.py", line 138, in poll
File "asyncore.py", line 80, in write
File "asyncore.py", line 76, in write
File "asyncore.py", line 395, in handle_write_event
File "asyncore_client.py", line 24, in handle_connect
File "asyncore_client.py", line 9, in __init__
File "asyncore.py", 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.SOMAXCONN could help me?

Thanks in advance.

 

[Laurent Pointal]

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_client.py", line 31, in <module>
File "asyncore.py", line 191, in loop
File "asyncore.py", line 138, in poll
File "asyncore.py", line 80, in write
File "asyncore.py", line 76, in write
File "asyncore.py", line 395, in handle_write_event
File "asyncore_client.py", line 24, in handle_connect
File "asyncore_client.py", line 9, in __init__
File "asyncore.py", 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.SOMAXCONN 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]

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_client.py", line 31, in <module>
File "asyncore.py", line 191, in loop
File "asyncore.py", line 138, in poll
File "asyncore.py", line 80, in write
File "asyncore.py", line 76, in write
File "asyncore.py", line 395, in handle_write_event
File "asyncore_client.py", line 24, in handle_connect
File "asyncore_client.py", line 9, in __init__
File "asyncore.py", 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.SOMAXCONN 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]

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]

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

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.