jmeter server mode setting

8/2/2019 JMeter Server Mode Setting

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JMeter mode setting : Helps in optimizing the load

generation

by PATEL AKHILKUMARon OCTOBER 3, 2011

Preface:Oftentimes, we have observed that the Jmeter samples of load scenarios dont match with

previous runs or dont match among different servers in standalone and client server

environment (distributed) etc. The results/samples depend on the many parameters like

SUT version, time of execution, data in back end, pacing of requests, think time between

requests and iterations and jmeter server/client performance etc. But these situations are

known and in general, load test engineers will try to setup and keep everything else

consistent during all the test execution. However, of if you still notice differences in

samples of hits per seconds, response time etc. during test execution from different

systems, then you should first verify your load test setup. This blog will will help you to

identify the initial steps for handling situations where you notice such differences:

Reduce sampling impact on load generation:The load generation process can be impacted highly (or negligible) based on the usage of

the memory, cpu, disk and network by the jmeter server and/or client. In all of these

scenarios, the network traffic can impact load generation heavily if we are using distributed

load execution scenario and system is sending all the samples to client immediately,

depending on the network and network adapter traffic handling capacity as well as on the

client system performance (which is obvious in all of the cases). Even jmeter sends the

samples back to client as they are generated and client writes it to file on receipt as a

default behavior means it uses network resources and client machine memory , disk and

cpu for same. So, if client machines network or other resources performance are faulty,

then it will impact on servers load generation activity adversely. To avoid this, set the

sample sending mode appropriately and you will find more on mode as moving forward on

this post.

There are total 7 modes for sampling in JMeter:

1. Standard

2. Hold

3. Batch

4. Statistical


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5. Stripped

6. StrippedBatch

7. Custom Implementation

Standard Default mode

This will send the samples to client as they are generated and client will write it to file

on receipt in distributed environment. Same way it will try to write in file immediately

in standalone environment. This will use less memory of load generating system but

impact on load generation as the next requests will be sent after the samples sending is

completed by network layer. So if the receiving clients network is slow then the

sample sending will be slow and which can impact on requests sending to SUT. Still if

the standard mode is required then try to reduce sampling interval means reduce theclient server communication and sampling size. It is advisable to run small test in

standalone mode and server mode and if you found difference then try to check the

network and system performance.

Hold mode

In this mode, the sample data is held in an array in the memory and will be saved to file

at the end of run by client after sending this data to client in distributed mode while it

get saved at last in standalone environment (not advisable to use this mode in

standalone if disk IO is performing well). But as you must have already guessed, it is a

memory consuming mode and it can be a major cause for system crash . So, it is

advisable tthink thrice before using this mode. For small load test it is among best load

generation modes. Run small tests and watch the increase in memory usage to

understand how risky it is to use this mode and how best to use this mode.

Batch modeThe system send samples in batch as per the defined threshold of samples or time. So

set following property appropriately:

num_sample_threshold number of samples in a batch (default 100)

time_threshold number of milliseconds to wait (default 60 seconds)

But sometimes it impact advertly if client network and system performance is not good.


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Statistical mode

This mode is mainly for summarized sampling and do not samples all the fields. Also,

the sampling rate is depends on the properties described with batch mode. The samples

would be grouped as per thread group name and sample label. It accumulates onlyfollowing fields and other fields that changes between samples will be ignored:

Fields which will be accumulated are: 1. Elapsed time, 2. Latency, 3. Bytes, 4. Sample

count and 5. Error count.

This mode somewhat reduces the samples data impact over the network and will use

very less resources of client as well in distributed environment. So it is advisable to

setup effiecient thresholds after consideration of client system performance, network

performance etc.

Stripped mode

This mode is nothing but standard mode without response data of successful samples.

StrippedBatch mode

This is nothing but the Batch mode without response data of successful samples.

Custom implementation mode

We can write our own custom sample sender class to customize the sampling behavior

and set the mode parameter to this custom sample sender class name.

This must implement the interface SampleSender and have a constructor which takes a

single parameter of type RemoteSampleListener.

For example:

public class PdfResponseSampleSender implements

SampleSender, Serializable { //The code will just show the

basic implementation and may be missing some required

implementation to fit in standard practice. private static

final Logger log = LoggingManager.getLoggerForClass();


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//SampleSender have a constructor which takes a single

parameter of type RemoteSampleListener. So following will

be used for that. private final RemoteSampleListener

listener; PdfResponseSampleSender(RemoteSampleListener

listener) { this.listener = listener; } //It will be fired

while sample started and stopped public void

sampleOccurred(SampleEvent event) { //Basically it is

advicable to create enum of mime types. but here we just

using it directoly in string variable String

pdfType="application/pdf"; SampleResult result =

event.getResult(); //Empty the response data if the media

type is not pdf.

if(result.getMediaType().compateTo(pdfType)!=0)

{ result.setResponseData(new byte[0]); } try

{ listener.sampleOccurred(event); } catch (RemoteException

e) { log.error("Error sending sample result over network

",e) } } }

We can set mode=org.example.load.PdfResponseSampleSender into

jmeter.properties and make sure that this class is reachable to jmeter.

Conclusion:I would say that we can resolve any load generation issue easily as jmeter isvery flexible and supports customization for most of the activities of L & P

testing.

If you have any questions, please post those in the comments below, and I

will try to answer those as soon as I can!

PS: All opinions in this post are my personal and it may or may not be of

Infostretch. Also, I have taken help of JMeter user manual and source code

for this blog post.

jmeter server mode setting

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