Solved

Max connections per socket

Posted on 2008-10-10
6
4,252 Views
Last Modified: 2013-11-17
I'm trying to figure out how/where I can determine the maximum number of connections a socket can have. We're using IBM AIX v5.2, ML 2.
0
Comment
Question by:ddavis78725
  • 3
  • 2
6 Comments
 
LVL 68

Accepted Solution

by:
woolmilkporc earned 125 total points
ID: 22688558
Hi,
have a look at this:
http://www.experts-exchange.com/OS/Unix/AIX/Q_22056628.html

Basically it's the "somaxconn" value which is of intererest here.
With "no -o somaxconn" you will probably see
"somaxconn = 1024" which is the default value in AIX
for the maximum listen backlog.

To change, enter "no -o somaxconn=[new value]"

For further information concerning "Netwok Options"
simply consult no' s manpage ("man no")

Also, you might want to consult the AIX documentation about the listen() subroutine found in:
http://publib.boulder.ibm.com/infocenter/pseries/v5r3/index.jsp?topic=/com.ibm.aix.commtechref/doc/commtrf2/listen.htm

Norbert



0
 
LVL 61

Expert Comment

by:gheist
ID: 22695365
Which way that socket will have those connections?

basically when you accept() it creates new socket. thats limited by system resources then.

it is sub-optimal to have more than 200 sockets/process (like apache).
0
 
LVL 68

Expert Comment

by:woolmilkporc
ID: 22701073
Hi,
now that we heard about listen() and accept(), here's the complete sequence
used to create sockets and work with them.
Only some preliminaries and the subroutine calls are shown, other coding is left out.
The clue is, as gheist said, the accept() subroutine (see my comment (==>) under accept() below).
The quoted ("") comments are extracted from IBM documentation (see the link I provided in my first post).
If you wish I can give you the complete sample program I once wrote for demonstration purposes.
Norbert
/* Some preliminaries: */
 

#include <stdio.h>

#include <sys/socket.h>

#include <netinet/in.h>
 

int sockfd, newsockfd;   /* fds for socket(), accept() */

struct sockaddr_in serv_addr, cli_addr; /* sockaddr_in from <netinet/in.h> */

long clilen; /* in linux 'int'! */

char buffer[];
 

/* socket() : 

"The socket subroutine creates a socket in the specified AddressFamily and of the specified type.

The socket subroutine returns a descriptor (an integer) that can be used in later subroutines 

that operate on sockets." */
 

sockfd = socket(AF_INET, SOCK_STREAM, 0); /* Address family, type, protocol */
 

/* bind() :

"The bind subroutine assigns a Name parameter to an unnamed socket. 

Sockets created by the socket subroutine are unnamed; 

they are identified only by their address family. 

Subroutines that connect sockets either assign names or use unnamed sockets." 

struct sockaddr comes from <sys/socket.h> */
 

bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr));
 

/* listen() :

"The listen subroutine performs the following activities:

- Identifies the socket that receives the connections. 

- Marks the socket as accepting connections. 

- Limits the number of outstanding connection requests in the system queue." */
 

listen(sockfd, 5);                      /* 5 = Queue depth! */
 

/* accept() :

"The accept subroutine extracts the first connection on the queue of pending connections, creates a new socket with the same properties as the specified socket, and allocates a new file descriptor for that socket

The accepted socket cannot accept more connections. 

The original socket remains open and can accept more connections"

==> This is what gheist said: 

The number of accepted sockets is limited only by your program or system resources. <== */
 

newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
 

/* Now do whatever you want with the accepted socket */
 

read(newsockfd, buffer, 255);

write(newsockfd, "Message xxxxxxxx", 17);
 

/* close the accepted socket */

close(newsockfd);
 

/* At the very end, close the original (listening) socket) */

close(sockfd);

Open in new window

0
Threat Intelligence Starter Resources

Integrating threat intelligence can be challenging, and not all companies are ready. These resources can help you build awareness and prepare for defense.

 
LVL 61

Expert Comment

by:gheist
ID: 22703563
Please add some remarkable comments in your code for us to see where you need to know the limit and on what resource.
0
 
LVL 68

Expert Comment

by:woolmilkporc
ID: 22703826
@gheist: I suppose you're talking to ddavis78725 and not to me (woolmilkporc)?
I'm a little confused, because ddavis78725 didn't supply any code yet, and my code above is only for explaining purposes.
0
 

Author Closing Comment

by:ddavis78725
ID: 31505072
This is what I was looking for. Thanks.
0

Featured Post

Highfive + Dolby Voice = No More Audio Complaints!

Poor audio quality is one of the top reasons people don’t use video conferencing. Get the crispest, clearest audio powered by Dolby Voice in every meeting. Highfive and Dolby Voice deliver the best video conferencing and audio experience for every meeting and every room.

Join & Write a Comment

In tuning file systems on the Solaris Operating System, changing some parameters of a file system usually destroys the data on it. For instance, changing the cache segment block size in the volume of a T3 requires that you delete the existing volu…
Why Shell Scripting? Shell scripting is a powerful method of accessing UNIX systems and it is very flexible. Shell scripts are required when we want to execute a sequence of commands in Unix flavored operating systems. “Shell” is the command line i…
Learn several ways to interact with files and get file information from the bash shell. ls lists the contents of a directory: Using the -a flag displays hidden files: Using the -l flag formats the output in a long list: The file command gives us mor…
Learn how to get help with Linux/Unix bash shell commands. Use help to read help documents for built in bash shell commands.: Use man to interface with the online reference manuals for shell commands.: Use man to search man pages for unknown command…

746 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

9 Experts available now in Live!

Get 1:1 Help Now