JMeter Basic Knowledge

JMeter Introduction

JMeter is an open source performance testing tool and interface test tool that works like LoadRunner: As a gateway between the browser and webserver, capturing browser requests and webserver responses, and then simulating users to access the scene through multithreading, Monitor the change of system resources to get performance. Compared with JMeter and LoadRunner, there is no qualitative difference, which is widely used because of its low cost.
Compared with LoadRunner and other commercial tools, the advantages are: low cost, flexibility and scalability (loading plug-ins, open api,ant Autorun, support for distributed), learning resources and channels (there are more learning resources and forum discussion). The disadvantage is: the requirement of the practitioners is higher, need to have good programming ability, English ability and analysis problem-solving ability. In addition to ease of use, LoadRunner's support protocols are broader, graphics reports are stronger, and IP spoofing is supported.

JMeter Main Features

1. Multi-protocol support
2. Can be achieved by recording playback
3. 100% Pure Java applications with high portability
4. Highly extensible (Open source code, multiple plugins).

Common terminology

• Test Plan: Test the root node of the script, setting the underlying configuration of the entire script, such as user-defined variables.
• Thread Group: Virtual user pool.
• Logical controller: Controls the order in which performance scripts are executed.
• Sampler: The base unit that makes a specific request to the server and waits for the server to respond before timing out.
• Assertion: Verifies that the server is returning the results to meet the requirements.
• Listener: Collects and displays test results.
• Configuring symbols: Setting common information for scripts
• Timers: Save and time-dependent configurations
• Pre-processor & Post Processor: Performs the appropriate processing before and after execution of the sampler in the execution range
• Workbench: Save test elements that you don't want to use temporarily

Thread Group

ramp-up period: How long does it take the jmeter to reach the maximum number of threads. Eg: if the number of threads set to 10,ramp-up period is set to 20 it means that every 2s starts a thread and starts all threads in 20s and lets them run. If the setting is too short, the initial phase of the test will give the server too much pressure; the setting is too long, the last thread may not have started when the first thread finishes executing, how can I find the appropriate ramp-up? It is recommended that beginners set the ramp-up= bus path number, and follow the appropriate adjustment according to the situation.

number of cycles and scheduling : The user can also configure the scheduler, start time/end time with the use, JMeter will be at the end of each cycle to see whether to reach the end time, if not, start the next round cycle. The delay time and duration are used together, and when these two options are enabled, the start time/end time is automatically ignored.

Advanced use

installation directory/configuration modifications
Ant auto-run/plug-in extension

JMeter Basic Knowledge