[squid-users] CLOSE_WAIT state in Squid leads to bandwidth drop

Hi All,
  I am doing a small test for bandwidth measurement of my test setup
while squid is running. I am running a script to pump the traffic from
client browser to Web-server via Squid box. The script creates
around 50 user sessions and tries to do wget of randomly selected
dynamic URL's.
After some time , I m observing a drop in bandwidth of the link, which
is connecting the webserver even there is no HIT in the squid cache.
I analyzed the netstat output during the problem scenario, I could
see Recv-q gets piled up in CLOSE_WAIT tcp state of squid and also
squid stays in CLOSE_WAIT state for more than a minute. The number of
squid sessions to webserver are getting dropped to 5 from 70, but
still tcp sessions from client to squid are around 80.

Without Squid, there is no drop in the bandwidth with the same load.

Why bandwidth is getting dropped when squid is running? Please provide
your suggestions on this.

Logs
------------
Squid version : 2.6.STABLE14

2013-11-25 10:17:53 Collecting netstat statistics...
tcp 248352 0 172.19.134.2:51439 194.50.177.163:80
     CLOSE_WAIT 5477/(squid)
tcp 77229 0 172.19.134.2:41998 64.15.157.134:80
     CLOSE_WAIT 5477/(squid)
tcp 15853 0 172.19.134.2:55344 64.136.20.39:80
     CLOSE_WAIT 5477/(squid)
tcp 30022 0 172.19.134.2:47485 50.56.161.66:80
     CLOSE_WAIT 5477/(squid)
tcp 30202 0 172.19.134.2:59213 198.90.22.194:80
     CLOSE_WAIT 5477/(squid)
tcp 9787 0 172.19.134.2:52761 184.26.136.73:80
     CLOSE_WAIT 5477/(squid)
tcp 106892 0 172.19.134.2:55109 184.26.136.115:80
     CLOSE_WAIT 5477/(squid)

2013-11-25 10:18:42 Collecting netstat statistics...

tcp 248352 0 172.19.134.2:51439 194.50.177.163:80
     CLOSE_WAIT 5477/(squid)

tcp 95558 0 172.19.134.2:42559 67.192.29.225:80
     CLOSE_WAIT 5477/(squid)

tcp 77229 0 172.19.134.2:41998 64.15.157.134:80
     CLOSE_WAIT 5477/(squid)

tcp 15853 0 172.19.134.2:55344 64.136.20.39:80
     CLOSE_WAIT 5477/(squid)

tcp 30022 0 172.19.134.2:47485 50.56.161.66:80
     CLOSE_WAIT 5477/(squid)

tcp 30202 0 172.19.134.2:59213 198.90.22.194:80
     CLOSE_WAIT 5477/(squid)

tcp 9787 0 172.19.134.2:52761 184.26.136.73:80
     CLOSE_WAIT 5477/(squid)

tcp 106892 0 172.19.134.2:55109 184.26.136.115:80
     CLOSE_WAIT 5477/(squid)

Squid info :

---------------

Connection information for squid:
        Number of clients accessing cache: 3
        Number of HTTP requests received: 257549
        Number of ICP messages received: 0
        Number of ICP messages sent: 0
        Number of queued ICP replies: 0
        Request failure ratio: 0.00
        Average HTTP requests per minute since start: 1443.2
        Average ICP messages per minute since start: 0.0
        Select loop called: 4924570 times, 2.174 ms avg
Cache information for squid:
        Request Hit Ratios: 5min: 0.0%, 60min: 0.0%
        Byte Hit Ratios: 5min: -0.0%, 60min: 3.2%
        Request Memory Hit Ratios: 5min: 0.0%, 60min: 0.0%
        Request Disk Hit Ratios: 5min: 0.0%, 60min: 0.0%
        Storage Swap size: 107524 KB
        Storage Mem size: 8408 KB
        Mean Object Size: 20.69 KB
        Requests given to unlinkd: 0

Regards,
Saravanan N
Received on Tue Nov 26 2013 - 11:37:15 MST