Is network connection can affect the connection between servers and JMeter? Are there any way to reduced the number of error percentage and high average response time?
Of course it can, 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.
Connect Time. JMeter measures the time it took to establish the connection, including SSL handshake. Note that connect time is not automatically subtracted from latency. In case of connection error, the metric will be equal to the time it took to face the error, for example in case of Timeout, it should be equal to connection timeout.
So the formula is:
Response time = Connect Time + Latency + actual server response time
If there are networking problems - it will have direct impact on the response time. Check out How to Analyze the Results of a Load Test Using BlazeMeter article to see how networking issues affect test results. So if you want to get more "clear" picture it's recommended to have JMeter load generator(s) having direct access to the application under test, to wit use LAN instead of Wi-Fi, make sure that NIC cards (as well as routers/switches) have enough bandwidth to serve the anticipated data volumes.
Related
I am testing a scenario with 400 threads. Although I am almost getting no errors, I have very high average response. What can bring about this problem? Seems like server gives no time-out but gives response so late. I've addded the summary report. It is as follows:
This table doesn't tell the full story, if response time seems "so high" to you - this is definitely the bottleneck and you can report it already.
What you can do to localize the problem is:
Consider using a longer ramp-up period, i.e. start with 1 user and add 1 more user every 5 seconds (adjust these numbers according to your scenario) so you would have arrival phase, the "plateau" and the load decrease phase. This approach will allow you to correlate increasing load and increasing response time by looking at Active Threads Over Time and Response Times Over Time charts. This way you will be able to state that:
response time remains the same up to X concurrent users
after X concurrent users it starts growing so throughput is going down
after Z concurrent users response time exceeds acceptable threshold
It would also be good to see CPU, RAM, etc. usage on the server side as increased response time might be due to lack of resources, you can use JMeter PerfMon Plugin for this
Inspect your server configuration as you might need to tune it for high loads (same applies to JMeter, make sure to follow JMeter Best Practices)
Use a profiler tool on server side during the next test execution, it will show you the slowest places in your application code
How is this possible that in Jmetetr increasing number of users (threads) in my test did not changed the latency (Response time)?
I got the same latency for 100 threads and for 300 threads.
Latency is the difference between the time when a request was sent and time when the response has started to be received.
As per JMeter Glossary
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.
Response time (= Sample time = Load time = Elapsed time) is a difference between the time when the request was sent and time when the response has been fully received.
As per JMeter Glossary
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.
So Response time always >= latency.
So it is possible that you may have same Latency for 100 and 300 threads but Response time will be different or increased.
If you have stable network connectivity between JMeter and Application Under Test it is expected that Latency wouldn't change not matter how many threads you kick off. It is "pure" network metric which tells how long did it take for the request to reach to the server.
Check out How to Analyze the Results of a Load Test article to see the impact of Latency for the end user
is there any way so that I can get the breakup of response time provided by JMeter. i.e.
Travel time of total request
processing time
Travel time of total response
I know JMeter works entirely on client side, and the response is the TTLB. But any plugin or by any means to achieve the same?
Thanks in advance.
You are asking what you should know.
There is no plugin which will give you such breakdown (getting processing time of server is impossible unless you have jmeter agents installed on target server. Monitoring agents are not part of Jmeter till now)
You can get approximate request travel time by using new Connect Time feature of Jmeter.
In practice,
Response time = processing time + latency
You can again find latency with multiple network tools or rough idea using ping (JMeter also gives latency. cross verify with ping or wanem)
Once you know latency you can get processing time.
I think you should get breakdown from this.
Add a listener to the thread group：
jp#gc - Composite Graph
jp#gc - Connect Times Over Time
jp#gc - Response Times Over Time
2.jp#gc - Composite Graph Configuration Connect Times Over Time and Response Times Over Time
3.The result after running:
The larger the difference between the two listeners is, the bottleneck is at the network layer, and the smaller the difference is at the server layer.
4.You can also view specific data by adding a View Results in Table listener
Server processing time =Latency - Connect Time
The larger the difference is, the bottleneck is at the service layer, and the smaller the difference is, the bottleneck is at the network layer.
Server processing time covers program processing time, queue waiting time, database query time and so on. This method can confirm whether the bottleneck of response time is at the network layer or the service layer. If it is at the service layer, we may need to analyze further. So the term server processing time seems inaccurate.
Is this a valid testing for checking of how much time to load a web under test with 500 concurrent user.
I run jmeter with a 500 thread user , ramp-up period = 50 and loop count forever. with a listener with "results in table" that also record the latency.
While jmeter is running, i try to load/browse the web under test using actual browser(in my case IE8) ,
and it loads in 7 secs. but based on the latency the majority of result is 50k++.
is the 7 secs load time in actual browser is consider a "response time result"? since it is load in actual browser.
another question:
is the latency 50k is converted to sec? means 50secs. to load the web under test if we based on the jmeter result?
kindly clarify this to me please :)
In simple words, Latency is network delay (time taken by network while transferring data)
In JMeter latency is time between, when request is sent to server till first byte of response reaches the client/Jmeter. If response time is very low enough then you wont get precise measure of latency. If Response time is high then probably you will get correct measure.
In Jmeter Latency shares the measure as response time i.e. ms/seconds.
Your 7sec in browser is (Response time (Processing time + Latency) + Rendering time). In Jmeter rendering time is not present (As it is not a browser). Though your rendering is very low as compared to response time but in cases heavy content websites rendering time is comparable. Thus should be considered.
I hope this clears your doubts :)
My website is hosted on cloud. I am running JMeter from my office. Now I want to know if the throughput that I get in Summary Report contain network latency also.
I have this kind of API details in my log file.
GET mywebsite/getBday 200 67
So for all getBday requests it gives me processing time of 67ms. But my JMeter show throughput 1.20 reqs/sec and latency here is 8.5 secs (latency = Average field from Summary Report).
Can you tell me if the throughput that I get in Summary Report contain network latency also. If so, how can I exclude it?
Response time includes network latency. It measures the time the request was made to the time the response was received.
How can jmeter know how long the request spent in transit, unless the server can respond with a time the request was received?
The only way to exclude network latency from jmeter results is to measure it at the server and send back the information in the response (or by some other method).
Most servers should have monitoring software running anyway, like carbon/graphite. You can use that to measure the true server response times, and show network latency.
As I am most testing Java stacks, I use jconsole as well on the same machine as jmeter for side by side comparison of graphs to determine real server capability.
"Can you tell me if the throughput that I get in Summary Report contain network latency also."?
The answer is no - throughput is a measure of the completion rate of requests and the formula for calculating it does not include latency. See below.
Probably worth looking up a definition for throughput. JMeter provides its own :
"Throughput is calculated as requests/unit of time. The time is calculated from the start of the first sample to the end of the last sample. This includes any intervals between samples, as it is supposed to represent the load on the server. The formula is: Throughput = (number of requests) / (total time)."
https://jmeter.apache.org/usermanual/glossary.html