JMeter Basic Knowledge

1. What is  jmeter's working principle? Submits a request to the server, and the result returned from the server retrieval request. 2. What is the role of  jmeter?     JMeter can be used to test the performance of static or dynamic resources (files, Servlets, Perl scripts, Java objects, databases and queries, FTP servers, or other resources). JMeter is used to simulate the ability to attach high loads on servers, networks, or other objects to test the compression capabilities of their services, or to analyze the overall performance of the services they provide under different load conditions. You can use the graphical interface provided by JMeter to analyze performance metrics or test server/script/object behavior under high load conditions. 3.    how can I see the script examples provided by JMeter? Under the \jmeter\jakarta-jmeter-2.0.3\xdocs\demos directory. 4. How do I set the number of concurrent users?     Select the test Plan node for the left tree in the visual interface, right-click and select the Add-> Thread Group, where the number of threads parameter is used to set how many users are sending the request. 5. Operating instructions for JMeter?    jmeter at run time, there is a small box in the upper right corner, which is run as green, and the box is white when finished running. 6. What is the role of  user parameters?     Increase the availability of scripts 7. In result, there will be a color font of HTTP response code, explain what? The HTTP response code is the HTTP return value, the color font is more noticeable, can use the user quick attention. Like a green 302. In this step, the return value is taken from the local catch, not the server. 8. How do I calculate ramp-up period time? Ramp-up period is the total time interval, in seconds, that occurs for each request. If number of threads is set to 5 and ramp-up period is 10, then the interval between each request is 10/5, or 2 seconds. Ramp-up period is set to 0, which is simultaneous concurrent requests. 9. What is the difference between get and post?     They are 2 different implementations of the HTTP protocol. Get refers to the server getting the required parameters from the request URL. As you can see from the request in result, get can see the parameters, but the post is active to the serverSend parameters, so these parameters are not generally seen. 10. What are the causes that could lead to error generation?    a.   HTTP errors, including non-responsive, results not found, data errors, etc.;   b.   JMeter itself causes errors. 11. Why is the total value in the aggregate report result not a true sum? JMeter the definition of total in the result is not exactly the sum, for ease of use, its value represents the column's representative value, such as the Min value, and it's total is the minimum value of the column. Is the meaning that total has in each column. Does the thread number of  jmeter provide multiple concurrent functions for different users? No, Thread number simply refers to concurrency, and if you need to implement multiple different user concurrency, we should use other methods, such as the way to create a CSV file outside of JMeter. 13. How do I implement concurrent requests when we need to simulate concurrent requests from different users to different servers at the same time? The     method is flexible, and we can pre-write different servers in thread. or write a fixed variable value to a CSV file beforehand, which can also be easily modified. Then add the file to user Parameters. What does the User parameter dummy mean?       The next line that simulates reading a file when its specific content is ${__csvread (${__property (User.dir)}${filename},next ())}. 15. What should I do when a test object jumps between multiple servers?     When the program runs, some HTTP and implicit functions carry additional server IPs, which we can get from their return values.   Why is the test object an HTTP and https promiscuous occurrence?    HTTPS is an encryption protocol, it is generally not recommended to use HTTP for security, but in some places, using HTTPS is too complex or difficult to implement, using the HTTP protocol. What is the default port for HTTP and HTTPS? The default port for    apache Server (Http) is 80;   ssl (HTTPS), which is the default port of 443. 18. Why do some pages fail when run, but don't affect the results at the end?     Reasons are more, it is worth mentioning that one isBecause the main page does not have a dependency on it, even if such a page goes wrong, it will not affect the normal results of the run, but it will affect the results of the test and the results of the analysis. 19. Why did the script start running with errors and later scripts to run?     There are settings in the thread group, and if Continue is selected, the entire thread will run until the end, even if there is an error in the previous script. Selecting Stop thread ends the current thread, and selecting Stop test ends all thread. The recommended option is stop Thread.     in regular Expression extractor will see that the value of the template is $1$, what does this value mean?    $1$ refers to the value inside the first (). If regular expression has more than one value, you can avoid unnecessary hassles with this method. What does the (. *)    regular expression mean?     That is a regex (regular expression). ’.’ Equivalent to the '? ' in the SQL language, indicating dispensable. ' * ' means 0 or more. ' () ' indicates that a value needs to be taken. (. *) to express a string of any length.   What to pay attention to when reading regular expression?     must ensure the absolute uniqueness of the values taken.    How can I tell what situation I need to add regular Expression Extractor?     Check the Send Parameters in the HTTP request, and if there is a parameter that is not given in the previous page, look it up in the original file and add regular Expression Extractor to the HTTP request of its previous page. 24. What does it mean when an empty HTTP request is sometimes present in an automatically acquired script?     is because there are some errors in getting the script, which is why the script tool. This error is not involved in running at run. 25. Why is there a rate of N/A in the results of the operation?     may be jmeter due to its own problems, running again can get the correct results. 26. What are the common HTTP error codes?     400 cannot resolve this request. &nBsp   403 Forbidden: Access is denied.     404 Cannot find a file or directory.     405 The HTTP action used to access the page is not licensed.     410 file has been deleted.     500 Server internal error.     501 Header value specifies that the configuration is not executed.     An invalid response was received by the 502 Web server as a gateway or proxy server. What does the send parameters in Http request mean?     refers to the values written in code and the values obtained in the custom variables, which are the parameters needed to run the page. Is 28.Parameters constantly passing through the page?     Yes. After the parameter is generated, it is passed to the desired page in the page. So we can catch it when the dynamic parameter is generated, or it can be captured on the previous page of the desired page. (However, there may be errors, preferably in generating page fetching) 29. Is the user operation fully simulated when using the JMeter test? Does the result be exactly the same as the user's operation?     Yes. The JMeter fully simulates the user operation, so the operation records are all written to the DB. Error data can be generated when a run fails, depending on whether the script check is rigorous or the error data goes into DB, causing a lot of trouble for the program to run.

JMeter Basics