CsvLogWriter plugin for JMeter

Introduction

Surely everyone who used standard listeners in JMeter, faced the following restrictions:

standard listeners do not allow getting detailed information on all subqueries specified in the test plan;
Standard listeners output information in XML format, which complicates the further analysis of logs using Excel and Pandas.

To circumvent these restrictions, it was decided to rework the formation of log files using the new CsvLogWriter plugin.

Assigned tasks

It was necessary to develop a plugin for JMeter, which would have the following functionality:

displaying the full text of the error in string format;
data capture by child subqueries.

In standard listeners for JMeter, fixing the full content of the error is possible in XML format, which causes inconvenience for analysis. There was a need to save the text of the error in a string format followed by recording, for example, in the CSV format to ensure the possibility of plotting in Excel and Pandas. Usually, the resulting log files do not display data on child subqueries. That is extremely inconvenient when using the complex structure of the test plan. An example of the structure is shown in Figure 1.

Figure 1. The structure of the test plan

When using standard listeners we will not be able to get the data of subqueries (embedded resources), CSVLogWriter gives us this opportunity.
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Description of plugin functionality pflb @ CsvLogWriter

A plugin pflb @ CsvLogWriter for JMeter was written during the work. The key features of this plugin include the fact that it can record the results of the work of the child subqueries and record the full text of the error, when it occurs, in plain text, and not in the XML format.

Log fields description

Log format

The data recorded in the log file are presented in Table 1.
Table 1. Log Format

No	Name	Type of	Description	Examples of values for the log column	unit of measurement
one	timeStamp	long	Start or end time of request		ms
2	elapsed	long	Request processing time: endTime - startTime - idleTime	49, 434	ms
3	label	String	JMeter component name
four	responseCode	String	Request response code	"200", "Non HTTP response code: java.net.UnknownHostException"
five	responseMessage	String	Deciphering the response code	"OK", "Internal Server Error"
6	threadName	String	Stream name	"Thread Group 1-1"
7	dataType	String	The data type in the response, in practice, takes two values - "bin" or "text"	"Bin", "text"
eight	success	boolean	Request Success Status	true or false
9	failureMessage	String	Error message in the case of the Assertion component, added to the sampler. In CsvLogWriter messages are written in the field. from all Assertion components, which generated an error. Only the first message is recorded in the base logger.
ten	bytes	int	The size of the answer. The value and calculation algorithm depend on the settings. sampler The value may be affected by responseData.length, headersSize, bodySize.		Byte
eleven	grpThreads	int	Number of active threads in the current group
12	allThreads	int	The number of active virtual users of all groups
13	URL	String	Link
14	Filename	String	Names of the file to which the responses are recorded. The field is filled in using Save Response to File Listener. This Listener is rarely used, usually the value of a column - empty line
15	Latency	int	The time to get the first server response. This time delay includes the time spent on connecting to the server delays due to the establishment of a secure connection and JMeter internal delays to receive first bytes of server response. If for some reason Sampler's work was suspended, and then resumed, then the Latency value will be adjusted for the duration of the suspension Sampler.		ms
sixteen	Encoding	String	Encoding. The response encoding is returned, if the response encoding is not set, This returns the default encoding value. The default encoding value is set to "Sampleresult.default.encoding". For HTTP Request, the default value is “ISO-8859-1”.	"ISO-8859-1", "UTF-8"
17	SampleCount	int	The number of samples. For HTTP Request, the value is 1. For JMS Sampler, subscribing to events and reading several messages at once, value equals the number of polling cycles or the number of read messages. The value is always greater than or equal to one.	12	PC
18	ErrorCount	int	Number of mistakes. For HTTP Request, the value is 0 if success and equals 1 if the request is not successful. For other samplers that process several messages at a time, value may be greater than 1.	0, 1	PC
nineteen	Hostname	String	Machine name
20	Idletime	int	Downtime		ms
21	Connect	int	Time spent on setting up a connection		ms
22	headersSize	int	Header size		Byte
23	bodySize	int	Body size		Byte
24	contentType	String	Content type from response header
25	endTime	long	Request End Time		ms
26	isMonitor	boolean	Sign whether the checkmark is Use As Monitor	true false
27	threadName_label	String	Name of thread and JMeter component
28	parent_threadName_label	String	Name of the thread and the parent JMeter component
29	startTime	long	Request start time		ms
thirty	stopTest	boolean	A sign of whether the test is stopped - the Stop button. Also in the settings of the Thread Group there is an option “Stop Test” on error. If in the column "stopTest" it is true, then this is exactly what happened. The script was interrupted by the current request.	true false
31	stopTestNow	boolean	The symptom stopped the test abruptly - the Shutdown button. Also in the settings of the Thread Group there is an option “Stop Test Now” on error. If in the column "stopTestNow" it is true, then this is exactly what happened. The script was interrupted by the current request.	true false
32	stopThread	boolean	A sign of whether the current thread has stopped. In the settings of the Thread Group there is an option “Stop Thread” on error. If the “stopThread” column is true, it means exactly this situation occurred. The script was interrupted by the current request.	true false
33	startNextThreadLoop	boolean	Does the replay start? In the settings of the Thread Group is the option "Start Next Thread Loop" on error. If the “startNextThreadLoop” column is true, it means exactly this situation occurred. The script was interrupted by the current request.	true false
34	isTransactionSampleEvent	boolean	A sign that the current event is a transaction (TransactionController). That is, it is only a grouping element.	true false
35	transactionLevel	int	Request nesting level If Transaction Controller hierarchy is used or subqueries have subqueries, then in this column there will be an nesting level.	0 for root query or root transaction controller. 1 for a subquery whose parent is the root.
36	responseDataAsString	String	Full error content in string format if it occurs, if success == false, then responseData will contain the complete response body
37	requestHeaders	String	Request headers
38	responseData	String	The full content of the error, if any, if success == false, then responseData will contain base64 full response body
39	responseHeaders	String	Response headers
40	<Variable name>	String	JMeter Variables

The log structure extends the basic CSV log format. The basic set of parameters can be found at the link jmeter.apache.org/usermanual/listeners.html#csvlogformat

The resulting CSV-log can be downloaded with any basic JMeter Listener that supports downloading of a CSV-log.
Also, additional columns appeared in the log, which can be useful in the analysis (pp. 22-35 of the Log format table).
The bodies and headers of responses and requests are recorded only in case of errors (pp. 36-39 of the Log Format table).
Also, the logs for the variables will be written to the log: jmeter.apache.org/usermanual/listeners.html#sample_variables - description of the ability to log the values of variables.

Interface

To run the plugin you must fill in the Filename field. The Filename field contains the path to the file where the work results will be recorded. You can set the directory manually, or select a file using the Browse button. If the specified file exists, a new file is created. The name of the new log file is formed by adding a postfix with the log file number to the original name.

Also on the form are flags. Using the checkboxes, you can manipulate the data recorded in the log. The Additional parameters checkbox is responsible for fixing additional parameters (22-35 lines in the Log Format table), Response data is responsible for fixing error text (36-39 lines in the Log Format table), User variables are responsible for fixing user variables.

The plug-in interface is shown in Figure 2.

Figure 2. Interface plug-in CSVLogWriter

Compare CSVLogWriter and Simple Data Writer plugin

In this section, we will try to compare the CsvLogWriter plugin and the standard Simple Data Writer.

The composition of the logged data

The Simple Data Writer listener gives the user the ability to customize the list of captured data. Figure 3 shows the output settings window.

Figure 3. Simple Data Writer fixer data settings window

The CsvLogWriter plugin always displays a basic list of parameters (similar to Simple Data Writer) and allows you to customize the display of a list of additional data using 3 checkboxes on the form:

Additional parameters - additional parameters (22-35 lines in the Log Format table);
Response data - error texts (36-39 lines in the Log format table);
User variables - user variables (for output, you need to run JMeter with the -Jsample_variables key).

A detailed list of fixed data is fixed in the code. But, as seen in Figure 3, Simple Data Writer cannot display error text in string format. The full text of the error is recorded only in XML format. For this reason, in the case when we need the text of errors, we have to keep 2 logs - 1 in CSV format (if further processing of the log with charting in Excel or Pandas is needed) and 1 in XML format.

Subquery Logging

Also, the Simple Data Writer listener does not record the results of the work of the child subqueries; accordingly, such a log file cannot be called exhaustive. To visually compare the amount of output data, run the test corresponding to the test plan in Figure 1, and look at the log files. The SimpleDataWriter log file is presented in Figure 4.

Figure 4. Simple Data Writer log file

As you can see in Figure 4, SimpleDataWriter does not display information on embedded resources. In turn, the CsvLogWriter plugin, by processing child subqueries, displays more information. The content of the log file of the CsvLogWriter plugin is presented in Figure 5.

Figure 5. CsvLogWriter log file

Performance comparison

We also analyzed the performance of the SimpleOccured method, which is responsible for event handling. Profiling was done in Java VisualVM. No subqueries were used in the test plan. For SimpleDataWriter, testing was started with recording to 1 CSV file and recording to 2 files - CSV and XML. The number of virtual users was 10, the number of repetitions is 100. The results of the comparison are shown in Table 2.

Table 2. Comparison of the performance of SimpleDataWriter and CsvLogWriter plugin

CsvLogWriter	SimpleDataWriter (CSV + XML)	SimpleDataWriter (CSV)
Duration (ms), number of calls	Duration (ms), number of calls	Duration (ms), number of calls
215, 2000	23076, 4000	101, 2000

Findings:

CsvLogWriter 10 times faster SimpleDataWriter (XML with maximum detail);
CsvLogWriter 2 times slower than SimpleDataWriter (CSV with maximum detail);
SimpleDataWriter (XML with maximum detail) is 20 times slower than SimpleDataWriter (CSV with maximum detail).

Link to plugin

github.com/pflb/Jmeter.Plugin.CsvLogWriter

Source: https://habr.com/ru/post/308098/

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