Varnish High CPU Usage / High Load Average

[Joseph Begumisa]

Hi,

I'm having an issue where when I start varnish, CPU usage rises in
about 3minutes to about 95% and load average rises to about 150.  I
then have to stop varnish and restart it before the system becomes
unresponsive.

Specs of the server i'm using are: Dual Quad-Core Intel Xeon CPU E5440
@ 2.83GHz with 16GB RAM.

I'm running version 2.1.5 and varnishd is started with the following options:

DAEMON_OPTS="-a 10.0.6.6:80
             -T localhost:6082 \
             -f /opt/varnish/etc/varnish/default.vcl \
             -p thread_pools=8 \
             -p thread_pool_min=100 \
             -p thread_pool_max=2000 \
             -p thread_pool_add_delay=2 \
             -p cli_timeout=25 \
             -p session_linger=50/100/150 \
             -h classic,30007 \
             -p listen_depth=4096 \
             -P /var/run/varnish/varnish.pid \
             -u varnish -g varnish \
             -s malloc,4G"

my default.vcl file is pretty basic for now:

backend web1 {
     .host = "10.0.6.66";
     .port = "80";
}

I was running varnishstat and obtained these stats immediately after I
stopped the varnish service since cpu usage was approaching 100%:

0+00:03:03
Hitrate ratio:       10      100      145
Hitrate avg:     0.9814   0.9796   0.9794

       40090         0.00       219.07 Client connections accepted
      143712         0.00       785.31 Client requests received
       95786         0.00       523.42 Cache hits
       11834         0.00        64.67 Cache hits for pass
        2321         0.00        12.68 Cache misses
        3096         0.00        16.92 Backend conn. success
       44665         0.00       244.07 Backend conn. reuses
           6         0.00         0.03 Backend conn. was closed
       45827         0.00       250.42 Backend conn. recycles
          87         0.00         0.48 Fetch head
       29726         0.00       162.44 Fetch with Length
        3339         0.00        18.25 Fetch chunked
          52         0.00         0.28 Fetch wanted close
           4         0.00         0.02 Fetch failed
        1583          .            .   N struct sess_mem
        1376          .            .   N struct sess
        2314          .            .   N struct object
        3037          .            .   N struct objectcore
        3037          .            .   N struct objecthead
         267          .            .   N struct vbe_conn
         800          .            .   N worker threads
         800         0.00         4.37 N worker threads created
           1          .            .   N backends
       11612          .            .   N LRU moved objects
       60661         0.00       331.48 Objects sent with write
       39967         0.00       218.40 Total Sessions
      143712         0.00       785.31 Total Requests
        1399         0.00         7.64 Total pipe
       44178         0.00       241.41 Total pass
       46203         0.00       252.48 Total fetch
    51252168         0.00    280066.49 Total header bytes
   795295815         0.00   4345878.77 Total body bytes
        7931         0.00        43.34 Session Closed


Any insights into what would cause that / changes I need to make would
be helpful.  Thanks.


Joseph