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This article mainly explains "how to use ab stress testing tools". Interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Let Xiaobian take you to learn "how to use ab stress test tools"!

1. Principle of AB

The ab command creates multiple concurrent access threads, simulating multiple simultaneous visitors accessing a URL. Its test target is URL-based, so it can be used to test the load stress of apache, but also to test the stress of other Web servers such as nginx, lighthttp, tomcat, IIS, etc.

The ab command is very light on the computer that issues the load; it does not consume a lot of CPU or memory. However, it will cause a huge load on the target server, and its principle is similar to CC attack. You also need to pay attention to your own test use, otherwise you will load too much at once. May cause the target server to run out of resources, or even cause a crash in serious cases.

II. Installation of ab

AB installation is very simple, if it is the source code to install apache, then it is even easier. After apache is installed, the ab command is stored in the bin directory of the apache installation directory. As follows:

/usr/local/apache2/bin

If apache is installed via yum RPM packages, the ab command is stored in the/usr/bin directory by default. As follows:

which ab

Note: if you don't want to install apache but want to use ab, you can install the apache toolkit httpd-tools. As follows:

yum -y install httpd-tools

Check if ab is installed successfully. You can switch to the above directory and use ab-V command to detect it. As follows:

ab -V

If ab is installed successfully, the ab-V command will display the appropriate version of ab, as shown above.

Note that the above is installed under the linux platform, if it is under the windows platform, we can also download the corresponding apache version to install.

III. Description of ab parameters

We can see how the ab command works with the help command. As follows:

ab --help

These parameters are described below.

-n Number of requests executed in the test session. By default, only one request is executed.

-c Number of requests generated at one time. The default is one at a time.

-t Maximum number of seconds the test is performed. The internal implicit value is-n 50000, which limits testing of the server to a fixed total time. By default, there is no time limit.

-p Files containing data that requires POST.

-P Provides BASIC authentication trust to a transit agent. The username and password are separated by a: and sent in base64 encoded form. This string is sent regardless of whether the server requires it (i.e., whether a 401 authentication requirement code is sent).

-T Content-type header information used by POST data.

-v Sets the level of detail displayed-4 or greater to display header information, 3 or greater to display response codes (404, 200, etc.), 2 or greater to display warnings and other information.

-V Display version number and exit.

-w Output results in HTML table format. By default, it is a two-column wide table with a white background.

-i Perform HEAD requests instead of GET.

-x Settings

Property.

-X uses proxy servers for requests.

-y Settings

Property.

-z Settings

Property.

-C Attach a Cookie to the request: line. This is typically a parameter pair of name=value, which can be repeated. - H appends additional header information to the request. This parameter typically takes the form of a valid header line containing pairs of fields and values separated by colons (e.g.,"Accept-Encoding:zip/zop;8bit").

-A provides BASIC authentication trust to the server. The username and password are separated by a: and sent in base64 encoded form. This string is sent regardless of whether the server requires it (i.e., whether a 401 authentication requirement code is sent).

-h Shows how to use it.

-d Do not display the message "percentage served within XX [ms] table"(support for previous versions).

-e Generates a comma-separated (CSV) file containing the corresponding percentage of time (in microseconds) required to process each corresponding percentage of requests (from 1% to 100%). Since this format has been "binarized," it is more useful than the 'gnuplot' format.

-g Write all test results to a 'gnuplot' or TSV(Tab-separated) file. This file can be easily imported into Gnuplot,IDL,Mathematica,Igor even Excel. One of the first lines is the title.

-i performs HEAD requests instead of GET. - k Enable HTTP KeepAlive, which executes multiple requests in one HTTP session. By default, KeepAlive is not enabled.

-q If the number of requests processed is greater than 150, ab outputs a progress count at stderr for every 10% or 100 requests processed. This-q tag suppresses this information.

IV. AB Performance Index

There are several indicators that are important during performance testing:

throughput rate (Requests per second)

A quantitative description of the concurrent processing capability of a server, in reqs/s, which refers to the number of requests processed per unit time under a certain number of concurrent users. The maximum number of requests that can be processed per unit of time for a given number of concurrent users is called maximum throughput.

a. Throughput is related to the number of concurrent users

b. Under different number of concurrent users, throughput rate is generally different.

Calculation formula: Total number of requests/Time taken to process these requests, i.e.

Request per second=Complete requests/Time taken for tests

It must be noted that this value represents the overall performance of the current machine, and the higher the value, the better.

Number of concurrent connections

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

Number of concurrent users (Concurrency Level)

Note the difference between this concept and the number of concurrent connections, where a user may have multiple sessions at the same time. Under HTTP/1.1, IE7 supports two concurrent connections, IE8 supports six concurrent connections, and FireFox3 supports four concurrent connections, so correspondingly, our number of concurrent users has to be divided by this base number.

Average user waiting time (Time per request)

Calculation formula: Time taken to complete all requests/(total requests/concurrent users), that is:

Time per request=Time taken for tests/（Complete requests/Concurrency Level）

Time per request:across all concurrent requests

Calculation formula: Time taken to process all requests/total requests, i.e.:

Time taken for/testsComplete requests

As you can see, it's the inverse of throughput.

It is also equal to the average user request waiting time/number of concurrent users.

Time per request/Concurrency Level V, ab Actual use

AB command parameters are more, we often use the-c and-n parameters.

[root@localhost ~]# ab -c 10 -n 1000 http://192.168.0.220:9088/

If a Cookie is used, simply type ab -n 100 -C key=value http://test.com/ If multiple cookies are needed, set Header: ab -n 100 -H "Cookie: Key1=Value1; Key2=Value2" http://test.com/

Apache tests throughput as: Requests per second#/sec.

Server Software represents the name of the Web server software being tested.

Server Hostname indicates the hostname of the requested URL.

Server Port represents the listening port of the Web server software being tested.

Document Path indicates the root absolute path in the URL of the request, and we can generally understand the type of the request by the suffix name of the file.

Document Length indicates the body length of the HTTP response data.

Concurrency Level represents the number of concurrent users, which is one of the parameters we set.

Time taken for tests represents the total time it took for all these requests to be processed.

Complete requests represents the total number of requests, which is one of the parameters we set.

Failed requests indicates the number of failed requests, where failures refer to requests that are abnormal in connection with the server, sending data, etc., and timeout after no response. If the header information of the received HTTP response data contains a status code other than 2XX, another statistical item named "Non-2xx responses" will be displayed in the test result, which is used to count the number of requests in this part. These requests are not counted as failed requests.

Total transferred represents the total length of response data for all requests, including the header information and body data length of each HTTP response data. Note that this does not include the length of HTTP request data, only the total length of application layer data flowing from the web server to the user PC.

HTML transferred represents the sum of the body data in all the response data of the request, that is, minus the length of the header information in the HTTP response data in Total transferred.

Requests per second throughput rate, calculated as:

Complete requests/Time taken for tests

Time per request Average user request waiting time, calculated as:

Time token for tests/（Complete requests/Concurrency Level）

Time per request (across all concurrent requests) Average server request waiting time, calculated as:

Time taken for tests/Complete requests

This is exactly the inverse of throughput. Time per request/currency Level.

Transfer rate represents the length of data these requests retrieve from the server per unit time, calculated as:

Total trnasferred/ Time taken for tests

This statistic is a good indication of how much bandwidth is required to exit a server when its processing capacity reaches its limit.

Percentage of requests served within a certain time (ms) This part of the data is used to describe the distribution of each request processing time. For example, in the above test, 80% of the request processing time does not exceed 6ms. This processing time refers to the previous Time per request, that is, for a single user, the average processing time of each request.

At this point, I believe everyone has a deeper understanding of "how to use ab stress testing tools," so let's actually operate it! Here is the website, more related content can enter the relevant channels for inquiry, pay attention to us, continue to learn!

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