Running with and without mongrel cluster

Can anybody explain why running 7 users without a mongrel cluster gives
better response than with a mongrel cluster and why for 25 -50 users the
response was about the same?

These are performance figures:

without mongrel cluster (and 4 mongrels)
throughput (request process/min) was about 1175 request/min

average response time:
7 users = 0.357 sec
25 users = 1.276 sec
50 users = 2.538 sec

===================================
with mongrel cluster (and 4 mongrels)
throughput (request process/min) was about 1100-1200 request/min

average response time:
7 users = 0.171 sec
25 users = 1.207 sec
50 users = 2.536 sec

thank you, Lena

Hello Lena.

The posted data doesn’t appear to support your assertions.

You said:

Can anybody explain why running 7 users without a mongrel cluster gives
better response than with a mongrel cluster and why for 25 -50 users the
response was about the same?

The average response time for 7 users, as you posted it is:

with mongrel cluster:
.0171 seconds

without mongrel cluster:
0.357 seconds

The rest of the data showed mongrel cluster with better response at 25
users
and identical response at 50. The most likely possibility for
identical reponse
at 50 is that the machine is baked, for 1 of 2 reasons, or a
combination of the
two:

  1. Rails is eating the CPU
  2. The DB is eating the CPU

In general, the performance you’re seeing is not very good, about 1/3
request/second (1200/3600) which, in my experience, is typically the
result of a very bad DB performance, potentially caused by missing
indexes.

Another possibility is an extreme number of queries per page tested.
We’ve
seen pages generating many thousands of SQL queries per page, for
instance.

[email protected] wrote:

The average response time for 7 users, as you posted it is:

with mongrel cluster:
.0171 seconds

No, it’s:
7 users = 0.171 sec

Lena

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