High CPU consumption, stops responding.

[Jason Hines]

First, I have to express how exciting this is. On my first conversion
from Mongrel to Passenger, it went very smooth. (Debian Linux, Ruby
1.8.5) I haven't seen a single hiccup - working wonderfully.

On my second conversion, the app is a bit larger and receives more
hits. (CentOS 5, Ruby 1.8.5) After switching to Passenger, Apache
stops serving any requests. Examining the logs, I see that it's
receiving a LOT of requests, and CPU/load is rising quickly.

After much tinkering, I decide to rule out the possibility of the
problem being my application itself, so I create a new Rails app on
the server, and use Passenger to serve it.

I begin hammering it (manually). After a while, I experience the same
problem. Eventually, Apacge stops responding, and I see the CPU usage
climb. At this point I see only these in the error_log.

[24231:ApplicationPoolClientServer.h:426] Client 0x9077fb0: received
message: ['setMax', '2']
[24231:ApplicationPoolClientServer.h:426] Client 0x9077fb0: received
message: ['setMax', '2']
[24231:ApplicationPoolClientServer.h:426] Client 0x9077fb0: received
message: ['setMax', '2']
[24231:ApplicationPoolClientServer.h:426] Client 0x9077fb0: received
message: ['setMax', '2']
[24231:ApplicationPoolClientServer.h:426] Client 0x9077fb0: received
message: ['setMax', '2']
[24231:ApplicationPoolClientServer.h:426] Client 0x9077fb0: received
message: ['setMax', '2']
[24231:ApplicationPoolClientServer.h:426] Client 0x9077fb0: received
message: ['setMax', '2']
[24231:ApplicationPoolClientServer.h:426] Client 0x9077fb0: received
message: ['setMax', '2']
[24231:ApplicationPoolClientServer.h:426] Client 0x9077fb0: received
message: ['setMax', '2']

.. Indefinitely, as the CPU usage climbs, until I restart Apache.

As you can see I have set RailsMaxPoolSize 2, in an attempt to control
this. Before this change the setMax message was 20 - but the result
is the same.

So at this point, I know it's not my application. This is a brand new
rails app. It must be something with this server's configuration and
I'm having trouble figuring out where it could be.

The server is hosted at RailsMachine w/ Apache 2.2.3.

Any ideas or suggestions are appreciated. Thanks.

[Jason Hines]

I've upgraded to Ruby 1.8.6-p114 on this server, and experiencing the
same problem.

[Jason Hines]

More information on this issue:

I've noticed with this installation of Passenger on CentOS, when I
hammer the URL using httperf, Passenger is not spawning new processes
like I believe it should. So what I may be experiencing here is that
I have a single application instance which is being flooded with
requests. Why Passenger is not spawning new instances, I'm not sure.
I'll keep looking and hopefully will find something enlightening soon.

[Eugenol]

I do experience the same problem and my rails app is somewhat idle as
it's just for testing, so no hammering.
I had to unload Passenger as apache became unresponsive and took 99%
WCPU.

Running apache 2.2.8 with ruby-1.8.6,1 on FreeBSD 6.2-RC1 (SMP) #2

[Eugenol]

> I do experience the same problem

I also discovered such errors on the same single line:

[0x11ac9:ApplicationPoolClientServer.h:0x1aa] Client
[0x80a5f000x11ac9: received message: :['setMax',
'20']ApplicationPoolClientServer.h
:0x1aa[] 0x11ac9Client :0x80a5f00ApplicationPoolClientServer.h:
received message: :['setMax', '20']0x1aa
] Client [0x80a5f000x11ac9: received message: :
[[[[[[[[[[[['setMaxIdleTime',
'120']ApplicationPoolClientServer.h0x11ac90x11ac90x11ac90x11ac90x11ac90x11ac90x11ac90x11ac90x11ac90x11ac90x11ac9
::::::::::::
0x1aaApplicationPoolClientServer.hApplicationPoolClientServer.hApplicationPoolClientServer.hApplicationPoolClientServer.hApplicationPoolClientServer.hApplicationPoolClientServer.hApplicationPoolClientServer.hApplicationPoolClientServer.hApplicationPoolClientServer.hApplicationPoolClientServer.hApplicationPoolClientServer.h] :::::::::::Client
0x1aa0x1aa0x1aa0x1aa0x1aa0x1aa0x1aa0x1aa0x1aa0x1aa0x1aa0x80a5f00] ] ] ] ] ] ] ] ] ] ] :
received message: Client Client Client Client Client Client Client
Client Client Client Client ['setMaxIdleTime',
'120']0x80a5f000x80a5f000x80a5f000x80a5f000x80a5f000x80a5f000x80a5f000x80a5f000x80a5f000x80a5f000x80a5f00
: received message: : received message: : received message: : received
message: : received message: : received message: : received message: :
received message: : received message: : received message: : received
message: ['setMax', '20']['setMax', '20']['setMax', '20']['setMax',
'20']['setMax', '20']['setMax', '20']['setMax', '20']['setMax', '20']
['setMax', '20']['setMax', '20']['setMax', '20']