*BSD News Article 67396


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From: kostya@osd.com
Newsgroups: comp.unix.bsd.bsdi.misc
Subject: how to increase the number of sockets per process?
Date: 1 May 1996 18:16:56 GMT
Organization: Seanet Online Services, Seattle WA
Lines: 33
Message-ID: <4m89qp$lpd@kaleka.seanet.com>
Reply-To: kostya@osd.com
NNTP-Posting-Host: ukbar.osd.com

We have an interesting problem with Apache 1.0.3 on BSDI 2.0.1. After we added  
our 125th virtual server apache stopped doing reverse DNS lookups. All apache  
transactions are now logged with ip addresses and not host names. Other  
programs on the same machine do reverse lookups fine at the same time. It seems  
to be some per process limitation. If I run "tcpdump udp port domain" I see  
that every http request generates 4 PTR lookups in rapid succession to each DNS  
server listed in resolv.conf. Then I see replies coming back. If I turn on  
queries logging on DNS I see the same thing. Nothing wrong with DNS servers.  
"netstat -p udp" on apache server shows this:

        111368 datagrams received
        0 with incomplete header
        0 with bad data length field
        0 with bad checksum
        109112 dropped due to no socket
        0 broadcast/multicast datagrams dropped due to no socket
        0 dropped due to full socket buffers
        2256 delivered
        111612 datagrams output

I guess all replies are "dropped due to no socket". Looks like it has enough  
sockets to send queries, but not enough to get replies. I tried "limit  
descriptors 256" or more and then restarted apache. Didn't help. OTOH it  
doesn't have a problem with answering incoming TCP (HTTP) connections or  
logging transactions for all virtual servers. It seems to be the problem only  
with datagram sockets.

Is there any kernel parameter that should be increased? 

Thank you
--
Konstantin Martynenko
Seanet Corporation