14. Introduction to listeners

A listener is a component that shows the results of the samples. The results can be shown in a tree, tables, graphs or simply written to a log file. To view the contents of a response from any given sampler, add either of the Listeners "View Results Tree" or "View Results in table" to a test plan. To view the response time graphically, add graph results. The listeners section of the components page has full descriptions of all the listeners.

Different listeners display the response information in different ways. However, they all write the same raw data to the output file - if one is specified.

The "Configure" button can be used to specify which fields to write to the file, and whether to write it as CSV or XML. CSV files are much smaller than XML files, so use CSV if you are generating lots of samples.

The file name can be specified using either a relative or an absolute path name. Relative paths are resolved relative to the current working directory (which defaults to the bin/ directory). JMeter also supports paths relative to the directory containing the current test plan (JMX file). If the path name begins with "~/" (or whatever is in the jmeter.save.saveservice.base_prefix JMeter property), then the path is assumed to be relative to the JMX file location.

If you only wish to record certain samples, add the Listener as a child of the sampler. Or you can use a Simple Controller to group a set of samplers, and add the Listener to that. The same filename can be used by multiple samplers - but make sure they all use the same configuration!

14.1 Default Configuration

The default items to be saved can be defined in the jmeter.properties (or user.properties) file. The properties are used as the initial settings for the Listener Config pop-up, and are also used for the log file specified by the -l command-line flag (commonly used for non-GUI test runs).

To change the default format, find the following line in jmeter.properties:


The information to be saved is configurable. For maximum information, choose "xml" as the format and specify "Functional Test Mode" on the Test Plan element. If this box is not checked, the default saved data includes a time stamp (the number of milliseconds since midnight, January 1, 1970 UTC), the data type, the thread name, the label, the response time, message, and code, and a success indicator. If checked, all information, including the full response data will be logged.

The following example indicates how to set properties to get a vertical bar ("|") delimited format that will output results like:.

02/06/03 08:21:42|1187|Home|200|Thread Group-1|text|true|
02/06/03 08:21:42|47|Login|200|Thread Group-1|text|false|Test Failed: 
    expected to contain: password etc.

The corresponding jmeter.properties that need to be set are shown below. One oddity in this example is that the output_format is set to csv, which typically indicates comma-separated values. However, the default_delimiter was set to be a vertical bar instead of a comma, so the csv tag is a misnomer in this case. (Think of CSV as meaning character separated values)


The full set of properties that affect result file output is shown below.

# Results file configuration

# This section helps determine how result data will be saved.
# The commented out values are the defaults.

# legitimate values: xml, csv, db.  Only xml and csv are currently supported.

# true when field should be saved; false otherwise

# assertion_results_failure_message only affects CSV output
# legitimate values: none, first, all
# response_data is not currently supported for CSV output
# Save ResponseData for failed samples

# Timestamp format - this only affects CSV output files
# legitimate values: none, ms, or a format suitable for SimpleDateFormat
#jmeter.save.saveservice.timestamp_format=yyyy/MM/dd HH:mm:ss.SSS

# For use with Comma-separated value (CSV) files or other formats
# where the fields' values are separated by specified delimiters.
# Default:
# For TAB, since JMeter 2.3 one can use:

# Only applies to CSV format files:
# Print field names as first line in CSV

# Optional list of JMeter variable names whose values are to be saved in the result data files.
# Use commas to separate the names. For example:
# N.B. The current implementation saves the values in XML as attributes,
# so the names must be valid XML names.
# JMeter sends the variable to all servers
# to ensure that the correct data is available at the client.

# Optional xml processing instruction for line 2 of the file:
#jmeter.save.saveservice.xml_pi=<?xml-stylesheet type="text/xsl" href="sample.xsl"?>

# Prefix used to identify filenames that are relative to the current base

# AutoFlush on each line written in XML or CSV output
# Setting this to true will result in less test results data loss in case of Crash
# but with impact on performances, particularly for intensive tests (low or no pauses)
# Since JMeter 2.10, this is false by default

# Put the start time stamp in logs instead of the end

# Whether to use System.nanoTime() - otherwise only use System.currentTimeMillis()

# Use a background thread to calculate the nanoTime offset
# Set this to <= 0 to disable the background thread

The date format to be used for the timestamp_format is described in SimpleDateFormat. The timestamp format is used for both writing and reading files. If the format is set to "ms", and the column does not parse as a long integer, JMeter (2.9+) will try the following formats:

Matching is now also strict (non-lenient). JMeter 2.8 and earlier used lenient mode which could result in timestamps with incorrect dates (times were usually correct).

14.1.1 Sample Variables

JMeter supports the sample_variables property to define a list of additional JMeter variables which are to be saved with each sample in the JTL files. The values are written to CSV files as additional columns, and as additional attributes in XML files. See above for an example.

14.1.2 Sample Result Save Configuration

Listeners can be configured to save different items to the result log files (JTL) by using the Config popup as shown below. The defaults are defined as described in the Listener Default Configuration section above. Items with (CSV) after the name only apply to the CSV format; items with (XML) only apply to XML format. CSV format cannot currently be used to save any items that include line-breaks.

Configuration dialogue

Note that cookies, method and the query string are saved as part of the "Sampler Data" option.

14.2 non-GUI (batch) test runs

When running in non-GUI mode, the -l flag can be used to create a top-level listener for the test run. This is in addition to any Listeners defined in the test plan. The configuration of this listener is controlled by entries in the file jmeter.properties as described in the previous section.

This feature can be used to specify different data and log files for each test run, for example:

jmeter -n -t testplan.jmx -l testplan_01.jtl -j testplan_01.log
jmeter -n -t testplan.jmx -l testplan_02.jtl -j testplan_02.log

Note that JMeter logging messages are written to the file jmeter.log by default. This file is recreated each time, so if you want to keep the log files for each run, you will need to rename it using the -j option as above.

JMeter supports variables in the log file name. If the filename contains paired single-quotes, then the name is processed as a SimpleDateFormat format applied to the current date, for example: log_file='jmeter_'yyyyMMddHHmmss'.tmp'. This can be used to generate a unique name for each test run.

14.3 Resource usage

Listeners can use a lot of memory if there are a lot of samples.

Most of the listeners currently keep a copy of every sample they display, apart from:

The following Listeners no longer need to keep copies of every single sample. Instead, samples with the same elapsed time are aggregated. Less memory is now needed, especially if most samples only take a second or two at most.

To minimize the amount of memory needed, use the Simple Data Writer, and use the CSV format.

14.4 CSV Log format

The CSV log format depends on which data items are selected in the configuration. Only the specified data items are recorded in the file. The order of appearance of columns is fixed, and is as follows:

14.5 XML Log format 2.1

The format of the updated XML (2.1) is as follows (line breaks will be different):

<?xml version="1.0" encoding="UTF-8"?>
<testResults version="1.2">

-- HTTP Sample, with nested samples 

<httpSample t="1392" lt="351" ts="1144371014619" s="true" 
     lb="HTTP Request" rc="200" rm="OK" 
     tn="Listen 1-1" dt="text" de="iso-8859-1" by="12407">
  <httpSample t="170" lt="170" ts="1144371015471" s="true" 
        lb="http://www.apache.org/style/style.css" rc="200" rm="OK" 
        tn="Listen 1-1" dt="text" de="ISO-8859-1" by="1002">
    <responseHeader class="java.lang.String">HTTP/1.1 200 OK
Date: Fri, 07 Apr 2006 00:50:14 GMT
Content-Type: text/css
    <requestHeader class="java.lang.String">MyHeader: MyValue</requestHeader>
    <responseData class="java.lang.String">body, td, th {
    font-size: 95%;
    font-family: Arial, Geneva, Helvetica, sans-serif;
    color: black;
    background-color: white;
    <cookies class="java.lang.String"></cookies>
    <method class="java.lang.String">GET</method>
    <queryString class="java.lang.String"></queryString>
  <httpSample t="200" lt="180" ts="1144371015641" s="true" 
     rc="200" rm="OK" tn="Listen 1-1" dt="bin" de="ISO-8859-1" by="5866">
    <responseHeader class="java.lang.String">HTTP/1.1 200 OK
Date: Fri, 07 Apr 2006 00:50:14 GMT
Content-Type: image/gif
    <requestHeader class="java.lang.String">MyHeader: MyValue</requestHeader>
    <responseData class="java.lang.String">http://www.apache.org/asf.gif</responseData>
      <responseFile class="java.lang.String">Mixed1.html</responseFile>
    <cookies class="java.lang.String"></cookies>
    <method class="java.lang.String">GET</method>
    <queryString class="java.lang.String"></queryString>
  <responseHeader class="java.lang.String">HTTP/1.1 200 OK
Date: Fri, 07 Apr 2006 00:50:13 GMT
Content-Type: text/html; charset=ISO-8859-1
  <requestHeader class="java.lang.String">MyHeader: MyValue</requestHeader>
  <responseData class="java.lang.String"><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
  <cookies class="java.lang.String"></cookies>
  <method class="java.lang.String">GET</method>
  <queryString class="java.lang.String"></queryString>

-- non HTTP Sample

<sample t="0" lt="0" ts="1144372616082" s="true" lb="Example Sampler"
    rc="200" rm="OK" tn="Listen 1-1" dt="text" de="ISO-8859-1" by="10">
  <responseHeader class="java.lang.String"></responseHeader>
  <requestHeader class="java.lang.String"></requestHeader>
  <responseData class="java.lang.String">Listen 1-1</responseData>
  <responseFile class="java.lang.String">Mixed2.unknown</responseFile>
  <samplerData class="java.lang.String">ssssss</samplerData>


Note that the sample node name may be either "sample" or "httpSample".

14.6 XML Log format 2.2

The format of the JTL files is identical for 2.2 and 2.1. Format 2.2 only affects JMX files.

14.7 Sample Attributes

The sample attributes have the following meaning:

deData encoding
dtData type
ecError count (0 or 1, unless multiple samples are aggregated)
hnHostname where the sample was generated
itIdle Time = time not spent sampling (milliseconds) (generally 0)
ltLatency = time to initial response (milliseconds) - not all samplers support this
ctConnect Time = time to establish the connection (milliseconds) - not all samplers support this
naNumber of active threads for all thread groups
ngNumber of active threads in this group
rcResponse Code (e.g. 200)
rmResponse Message (e.g. OK)
sSuccess flag (true/false)
scSample count (1, unless multiple samples are aggregated)
tElapsed time (milliseconds)
tnThread Name
tstimeStamp (milliseconds since midnight Jan 1, 1970 UTC)
varnameValue of the named variable
JMeter allows additional variables to be saved with the test plan. Currently, the variables are saved as additional attributes. The testplan variable name is used as the attribute name. See Sample variables (above) for more information.

14.8 Saving response data

As shown above, the response data can be saved in the XML log file if required. However, this can make the file rather large, and the text has to be encoded so that it is still valid XML. Also, images cannot be included. Only sample responses with the type TEXT can be saved.
Another solution is to use the Post-Processor Save_Responses_to_a_file. This generates a new file for each sample, and saves the file name with the sample. The file name can then be included in the sample log output. The data will be retrieved from the file if necessary when the sample log file is reloaded.

14.9 Loading (reading) response data

To view an existing results file, you can use the File "Browse…" button to select a file. If necessary, just create a dummy testplan with the appropriate Listener in it.

Results can be read from XML or CSV format files. When reading from CSV results files, the header (if present) is used to determine which fields were saved. In order to interpret a header-less CSV file correctly, the appropriate JMeter properties must be set.

JMeter does not clear any current data before loading the new file thus allowing files to be merged. If you want to clear the current data, use the menu item: Run → Clear (Ctrl + Shift + E) or Run → Clear All (Ctrl + E) before loading the file.

14.10 Saving Listener GUI data

JMeter is capable of saving any listener as a PNG file. To do so, select the listener in the left panel. Click Edit → Save Node As Image. A file dialog will appear. Enter the desired name and save the listener.

The Listeners which generate output as tables can also be saved using Copy/Paste. Select the desired cells in the table, and use the OS Copy short-cut (normally Ctrl + C). The data will be saved to the clipboard, from where it can be pasted into another application, e.g. a spreadsheet or text editor.

Figure 1 -
Figure 1 - Edit → Save Node As Image