Shibd load testing Issues

[raghavendra harapanahalli]

I have been trying to perform load testing using the below configuration for
Shibboleth SP  (installed on a dedicated server)

Shibboleth SP 2.4.2 64 bit
Red Had Linux OS on Dual core  (each core of Intel(R) Xeon(R) CPU X5570  @
2.93GHz )
4GB RAM

I'm running the load tests using JMeter performing the following steps using
50 threads for 300 seconds(5 mins):
1. Request protected url in apache(redirects to an external authenticator
hosted in weblogic)
2. Return after external authentication to IDP and prepare the Authn
Response to be posted to SP
3. Post /Shibboleth.sso/SAML2/POST with relaystate and samlresponse to the
SP.

The first two steps behave quite well in a high load, however, step 3 starts
quite fast but very quickly, shibd reaches 99% cpu (memory utilization is
stable) and response time increases from 50ms up to beyond a minute in a
very short time.

Tried reducing the number of Threads in Jmeter but the problem persisted.

Came across this previous post with a similar issue and tried al the tweaks
that Scott suggested but the problem is persisting

http://shibboleth.1660669.n2.nabble.com/shibd-load-test-td5862748.html

tweaks i tried are as below
-- changed to worker mpm mode
-- reduce the ulimit from 1024 to 512

I believe the server configuration is decent enough and the cpu utilization
is peaking at even very low hit rates (treid even with 2 Threads in Jmeter)
which is unacceptable in a production scenario.

Kidnly suggest if there is something i am doing wrong or if there can be any
tweaks done in shibd to improve this.
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