Calculate network latency

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I am starting to test with the jmeter. I have read documentation and outstanding questions about the values that are obtained from jmeter, at least in the version I have are: timeStamp, elapsed, label, responseCode, responseMessage, threadName, dataType, success, failureMessage, bytes, sentBytes, grpThreads, allThreads, URL, Latency, IdleTime and Connect.

I am launching against a web page that has a server. The times are

elapsed (response time), is the time it takes to complete the request (from start to finish)

Latency is the time from when you start transmitting until you receive the first byte (from start to first response. Includes connect)

Connect is the time it takes to make a TCP connection.

My question would be: To take into account network latency, what data would need to be collected?

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jmeter

1 Answers

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If you want to measure the time which takes the request to travel from the system under test to JMeter just subtract Latency from Elapsed time and that should be it.

Looking into JMeter Glossary:

Elapsed time. JMeter measures the elapsed time from just before sending the request to just after the last response has been received. JMeter does not include the time needed to render the response, nor does JMeter process any client code, for example Javascript.

Latency. JMeter measures the latency from just before sending the request to just after the first response has been received. Thus the time includes all the processing needed to assemble the request as well as assembling the first part of the response, which in general will be longer than one byte. Protocol analysers (such as Wireshark) measure the time when bytes are actually sent/received over the interface. The JMeter time should be closer to that which is experienced by a browser or other application client.

So TTLB minus TTFB should give you the time to transfer the response from server to JMeter and given you have at least 2 samplers with different response size you can figure out the network throughput for a single byte.

Some extra information can be obtained from the JMeter log file, if you enable debug logging on protocol level you will see timestamps for all the events in the log:

The line which needs to be added to log4j2.xml file:

<Logger name="org.apache.http" level="debug" />

Example output:

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