Understanding Concurrent Users and User Population
3-2 Oracle HTTP Server powered by Apache Performance Guide
relationship between the number of potential users and the number of concurrent users. This is determined by the think time and the average response time for your application. To determine memory requirements, you also need to consider the number of concurrent executing users (not the total user population) times the cost per user. Tabl e 3–1 provides an example of the impact of think time and service time on the concurrency and resulting performance of a system. Note: The MaxClients setting in your httpd.conf file limits the
number of concurrently executing users. See "MaxClients" on page 4-9 for information on the MaxClients directive.Table 3–1 Concurrent executing users
User
population1
1User population - total users.
Think
time
(sec)2
2Think time - the time the user is not engaged in actual use of the processor (the time between
requests).
Service
time
(sec)3
3Service time (seconds) - elapsed time to complet e the operation measured for a single user.
Range of
concurrent
users4
4Range of concurrent users - the number of users measured on the server, taken in snapshots from the
server-status display (requests currently being processed). See "Using the mod_status Utility" on
page 3-3 for information on server-status.
Average
response
Time
(sec)5
5Average response time - response time measured at the client under load.
Requests per
second
(throughput)6
6Requests per second (throughput) - number of requests processed.
CPU
utilization
(%)7
7CPU utilization - average total CPU utilization as a percentage.
100 0 0.3 100 5.2 19 99
100 1 0.3 65-100 4.2 19 99
100 10 0.3 0-32 0.9 9 48
100 10 0.6 0-53 2.9 8 80