<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD><TITLE>RE: [JDEV] Performance</TITLE> <META content="text/html; charset=iso-8859-1" http-equiv=Content-Type> <META content="MSHTML 5.00.3013.2600" name=GENERATOR></HEAD> <BODY> <DIV>The number of open sockets is indeed a big issue. The main memory 'eater' with multiple TCP/IP sockets is the kernel-level memory. At last I heard (which is another way of saying 'don't hold me to these numbers'), one active client connection took about 50k.</DIV> <DIV> </DIV> <DIV>With Linux, you have to do some kernel reconfiguration to get above 1024 file descriptors per process(temas today explained how to do it without recompiling the kernel, I need to explore this area of l-k more). a TCP connection is of course represented by a file descriptor.</DIV> <DIV> </DIV> <DIV>Note that much of the memory above is stack for each session. Even if you somehow eliminated the stack and the heap for each open connection, you'd find that the kernel memory for each client was about 16k (which is unswapable). You could possibly get this down to 8k (two 4k pages), but one 4k page does not have enough space to handle an active TCP connection.</DIV> <DIV> </DIV> <DIV>At least (from the numbers I've seen) the server is not CPU-limited.</DIV> <DIV> </DIV> <DIV>So unless you rewrote the Jabber server to not require separate stack spaces, and rewrote some operating system kernel to somehow 'share' a large datablock between many 'idle' TCP sockets, I don't know of any way you could acheive an extremely large number of users on one server. I do not know of any operating system that can handle an extremely large number of TCP connections- 10k is ususlly the first real limit a machine hits.</DIV> <DIV> </DIV> <DIV>It would seem the only other feasible you can manage this is to rewrite the Jabber server to allow clusters of machines. You could also attempt to modify the Jabber protocol to use UDP, but then you would have something new that wasn't Jabber anyways.</DIV> <DIV> </DIV> <DIV>-David Waite</DIV> <BLOCKQUOTE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; PADDING-LEFT: 5px"> <DIV align=left class=OutlookMessageHeader dir=ltr>-----Original Message----- From: jdev-admin@jabber.org [mailto:jdev-admin@jabber.org]On Behalf Of Michael Petras Sent: Tuesday, April 25, 2000 10:20 AM To: 'jdev@jabber.org' Cc: Douglas Petty Subject: RE: [JDEV] Performance </DIV> One aspect of performance I was wondering how Jabber addresses is the number of open sockets. Does the Jabber server keep a TCP socket open for each logged in client? What determines how many sockets can be open simulatenously using Linux? Does Jabber or Linux do any tricks to increase the number of open sockets (such as transforming open, but quiet sockets into some placeholder objects that use minimal memory until the next message)? Does anyone know of any implementations that do this? Does anyone know how big IM/presence servers like Yahoo, ICQ or AOL handles this? Our applications have to communicate with tens to hundreds of thousands of fairly low traffic clients. Our servers run on Windows NT where the limit on open sockets is a significant issue. Thanks in advance for any info.                                                                              Thnx,                                                                                  Mike Petras <UL> -----Original Message----- From:   David Waite [SMTP:mass@ufl.edu] Sent:   Tuesday, April 25, 2000 8:26 AM To:     jdev Subject:        RE: [JDEV] Performance It sounds more like the test was throttled due to you sending too many messages at once, rather than any sort of scalability or other type of limitation in the Jabber server. -David Waite -----Original Message----- Hi ,         The real issue which I want to highlight is not spammers but the Scalability of Jabber . The tests which I performed on Jabber clearly showed that it slows down which is definitely not acceptable in real-life situations . Jabber has to be more scalable than it is now . Any Thoughts and Ideas ? Regards , chetan s . ithal _______________________________________________ jdev mailing list jdev@jabber.org <A href="http://mailman.jabber.org/listinfo/jdev" target=_blank>http://mailman.jabber.org/listinfo/jdev</A> </UL></BLOCKQUOTE></BODY></HTML>