Several basic concepts to be mastered in stress testing-practical skills

1: Throughput (Requests per second)

A quantified description of the server's concurrent processing capacity, in units of reqs/s, refers to the number of requests processed within a unit time of a concurrent user. The maximum number of requests processed per unit of time for a concurrent user, called the maximum throughput rate.

Remember that throughput is based on the number of concurrent users. This sentence represents two meanings, 1: Throughput and the number of concurrent users, 2: Different concurrent users, the throughput rate is generally different.

Calculation formula: Total requests/processing time to complete the number of requests, i.e.

Request per second = Complete Requests/time taken for tests

2: Concurrent connections (the number of concurrent connections)

The number of concurrent connections refers to the number of requests received by the server at a given moment, simply speaking, a session.

3: Concurrent users (the number of concurrent users,concurrency level)

To be aware of the distinction between this concept and the number of concurrent connections, a user may produce multiple sessions at the same time, the number of connections. Under http/1.1, IE7 supports two concurrent connections, IE8 supports 6 concurrent connections, and FIREFOX3 supports 4 concurrent connections, so we have to divide the number of concurrent users by this cardinality accordingly.

4: Average user request wait time (times per request)

Calculation formula: The amount of time spent processing all requests (total requests/concurrent users), i.e.

Time to request = time taken to tests/(Complete requests/concurrency level)

5: Server average Request latency (time of Request:across all concurrent requests)

Calculation formula: The number of time/total requests spent processing all requests to complete, that is

Time taken For/testscomplete requests

As you can see, it is the reciprocal of the throughput rate.

At the same time, it also = user average request wait time/concurrent user number, namely

Time/request/concurrency Level

II: Specific approaches

1: Pressure test Tool selection

The heavyweight tool has visual Studio's own tools, as well as loader Runner (LR), a lightweight tool with Apachebench in the Apache project, called AB. You can download it here:Ab.zip.

Simple use and parameter introduction of 2:AB

The above test is based on one of my asp.net pages. For stress testing, must always do, if you do not know their application can carry the number of concurrent users, it is basically throwing a time bomb.