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From Andrew Wilson <>
Subject (fwd) Re: Solaris 2.4 http server hangs on accept() during high load
Date Mon, 26 Jun 1995 11:16:02 GMT

I dunno if anyone's seen this from c.i.w.s.u.  Any comments.


     Andrew Wilson	     URL:
Elsevier Science, Oxford   Office: +44 01865 843155    Mobile: +44 0589 616144

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>From Fri Jun 23 13:23:03 1995
Date: Fri, 23 Jun 1995 13:25:44 +0100
From: Ade Rixon <>
Subject: (fwd) Re: Solaris 2.4 http server hangs on accept() during high load
Newsgroups: comp.infosystems.www.servers.unix,comp.unix.solaris
Organization: Elsevier Science Ltd, Oxford, UK
Content-Length: 1518

Seen this?

>From: (Andrew Payne)
>Date: 20 Jun 1995 15:08:11 -0400

In article <3s4uhi$> (Erwin Bolwidt) writes:

>>>We're running the Apache 0.6.2 http server on a dual sparc Sparcserver 
>>>1000. The server is getting 150,000 - 160,000 hits a day and the number 
>>>is still growing.
>>I ran into a similar problem with Apache 0.6.2 & Solaris 2.4 on a Sparc 20.
>>Any large number of connects (~8K in 15 seconds) will cause terrible problems
>>throughout the TCP networking code.  The problem also happened with NCSA
>>httpd 1.3, 1.4, and Netscape's Commerce Server.
>>Unfortunately, I cant seem to convince Sun that there is a problem with their
>>OS, so as far as I know there is no official bug.

This is a long shot diagnosis, because I don't know the internal 
architectures for the various servers, but Solaris does not support 
multi-process accept() calls on the same file descriptor.

If the server does the following:

    accept()		/* in each listener process */

you can {panic,crash,hang} the Solaris kernel under very heavy load.  We 
ran into this problem when we were stress-testing our own WebServer.

The official workaround from Sun is to serialize the calls to accept().

Andrew Payne                
Open Market, Inc.

 | Ade Rixon, Elsevier Science Ltd     |  |

		"Gentlemen!! Let's broaden our minds!"
							- The Joker

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