I am trying to stress test my server.
To do so I am using Jmeter and here is my set up:
I use
my Setup
Thread: 1000
schedule for 3 mins
So as you see I keep going with 1000 thread for a period of 3 mins.
But when I look at the throughput I only get around 230 per second
results
So what should I do to increase the through put to for example 1000000 per second? How come increasing the thread which I assume means more load does not increase throughput?
According to JMeter Glossary
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).
Throughput explicitly relies on the application response time. Looking into your results, the average response time is 3.5 seconds therefore you will not get more than 1000 / 3.5 = 285 requests per second
Theoretically you could use Throughput Shaping Timer and Concurrency Thread Group combination, this way JMeter will kick off extra threads if the current amount is not enough to reach/maintain the desired throughput, however looking into 8.5% error rate and maximum response time for your application > 2 minutes my expectation is that you will not be able to get more throughput because most probably your application is overloaded and cannot respond faster.
Throughput measures the number of transactions or requests that can be made in a given period of time. basically, it lists the number of requests server managed to serve in a given time period. Throughput value depends on lot of factors and maybe your application under test not able to cater the expected load.
So with 1000 threads, you can't expect a 1000 throughput.
It's up to you to find out how much throughput your application can handle. For that maybe you need to do different optimizations on your side like optimize your script, distribute load via JMeter execution, increase theard count,...etc
Related
I am conducting a performance test (TPS) using jmeter.
I am requesting about 10,000 TPS, but the following two results are different.
(Position that 10,000 TPS responds normally)
1000 thread x 600 target throughput(in samples per minute)
100 thread x 6000 target throughput(in samples per minute)
I think the two results should be the same, but why is the response time delayed as the thread increases?
I think the two results should be the same - why they would be the same?
Let's imagine your system has fixed response time of 1 second, in that case:
With 1000 threads you will get 1000 requests per second and you can limit the throughput to 10 requests per second using the Constant Throughput Timer
With 100 threads you will get 100 requests per second, no limiting is required
And what if response time is 2 seconds?
With 1000 threads you will get 500 requests per second
With 100 threads you will get 50 requests per second
Constant Throughput Timer:
acts precise enough on "minute" scale, if your test lasts less than minute it might not apply the throughput
can only pause the threads to limit the throughput (requests per minute) to the desired value. If current number of threads is not enough in order to conduct the required load - the time won't have any effect.
If you want to send requests at the rate of 10000 TPS it worth considering going for the Throughput Shaping Timer and Concurrency Thread Group combination connected via the Feedback Function in this case JMeter will be able to kick off extra threads if current number is not sufficient.
But also be informed that:
JMeter should be able to start as many threads as needed to send 10000 TPS so make sure to follow JMeter Best Practices or even consider going for Distributed Testing Mode
Application needs to be able to handle the load and respond fast enough, JMeter waits for the previous response before starting the new request so if application is able to serve i.e. 5000 requests per second only you won't be able to reach 10000 by any means
As per the Documentation - "Of course, if the server is not able to handle such a load, the throughput will be lower." How is this behavior handled and throughput calculated?
Suppose I set the target throughput as 1500/min but my system could handle only 1000/min, what kind of feedback behavior is expected by JMeter and how is the total throughput affected?
Will the JMeter still try to achieve 1500/min with higher error rate (for failed requests) or JMeter shoots the throughput to 1500/min but gradually comes back near to 1000/min based on certain factors like error rate? If yes, what are the factors determining this step-down, any insight/reference to understand this step-down behavior?
Either you do not have enough threads in the test plan to achieve your desired TPS or your application response time is higher.
The total number of requests you will be able to make through JMeter depends on your application response time.
So you will need at least 25 threads to achieve 1500/min if your average response time is 1 second (assuming there is only 1 request).
If throughput isn't increasing even after providing with enough threads but the response time increasing and some of your requests got failed, then this indicates the performance bottleneck!
JMeter cannot send requests faster than your application is capable of responding. If your application can only serve 1000 requests per minute - you will have 1000 requests per minute no matter how many threads you have in the Thread Group or how many requests per minute you specify in the Constant Throughput Timer.
Also be aware that:
Constant Throughput Timer can only pause the Threads, it will not do anything if the current amount of threads is not enough to reach/maintain the desired throughput
Constant Throughput Timer is accurate enough on minute level so consider choosing proper ramp-up settings otherwise you can stress your application during first minute of your test
How can I find out maximum throughput my application can achieve within sla of 1 sec as response time.i.e response time should be within 1 sec
Currently I am using throughput controller and setting up the required throughput per minute, but I need to know max throughput my application can deliver with average response time less then 1 sec.
Using Thread Group, set Number of Threads (users) to some big number and set rump-up period to e.g.: 600s (10min)
Jmeter will slowly increase throughput and you can monitor Max response time in Summary report (column Max) - when it starts reaching 1s, you can read your desired Throughput (in Throughput column) Then I recommend set this number to Number of threads, decrease rump-up and run test for couple of hours.
Avoid using sleeps in your loop in JMeter. Beware of cache at application side. Monitor Faults in Error columns and check system health on both sides (CPU,mem,IO,Netw,...)
Please note that Throughput Controller does not control the throughput.
Following is from the JMeter official site.
This controller is badly named, as it does not control throughput.
Please refer to the Constant Throughput Timer for an element that can
be used to adjust the throughput.
You may use plugin Throughput Shaping Timer if you want to have controlled throughput changing with the time.
Change the threads (virtual users) and throughput to check the maximum through that can be handled by the server.
Use Duration Assertion to check the response time of each desired sampler.
Just don't limit JMeter's throughput.
Start with 1 thread (virtual user) and gradually increase the load until you see response times exceeding 1 second (you can use i.e. AutoStop Listener plugin for automatically stopping the test when average response becomes higher than 1 second)
Once done you can look into Transactions per Second and Server Hits per Second, it will give you the number you're looking for.
I'm getting the following results, where the throughput does not have a change, even when I increase the number of threads.
Scenario#1:
Number of threads: 10
Ramp-up period: 60
Throughput: 5.8/s
Avg: 4025
Scenario#2:
Number of threads: 20
Ramp-up period: 60
Throughput: 7.8/s
Avg: 5098
Scenario#3:
Number of threads: 40
Ramp-up period: 60
Throughput: 6.8/s
Avg: 4098
The my JMeter file consists of a single ThreadGroup that contains a single GET.
When I perform the request for an endpoit where the response time faster (less than 300 ms) I can achieve throughput greater than 50 requests per seconds.
Can you see the bottleneck of this?
Is there a relationship between response time and throughput?
It's simple as JMeter user manual states:
Throughput = (number of requests) / (total time)
Now assuming your test contains only a single GET then Throughput will be correlate average response time of your requests.
Notice Ramp-up period: 60 will start to create threads over 1 minute, so it will add to total time of execution, you can try to reduce it to 10 or equal to Number of threads.
But you may have other sampler/controllers/component that may effect total time.
Also in your case especially in Scenario 3, maybe some requests failed then you are not calculating Throughput of successful transactions.
In ideal world if you increase number of threads by factor of 2x - throughput should increase by the same factor.
In reality the "ideal" scenario is hardly achievable so it looks like a bottleneck in your application. The process of identifying the bottleneck normally looks as follows:
Amend your test configuration to increase the load gradually so i.e. start with 1 virtual user and increase the load to i.e. 100 virtual users in 5 minutes
Run your test and look into Active Threads Over Time, Response Times Over Time and Server Hits Per Second listeners. This way you will be able to correlate increasing load with increasing response time and identify the point where performance starts degrading. See What is the Relationship Between Users and Hits Per Second? for more information
Once you figure out what is the saturation point you need to know what prevents your application from from serving more requests, the reasons could be in:
Application simply lacks resources (CPU, RAM, Network, Disk, etc.), make sure to monitor the aforementioned resources, this could be done using i.e JMeter PerfMon Plugin
The infrastructure configuration is not suitable for high loads (i.e. application or database thread pool settings incorrect)
The problem is in your application code (inefficient algorithm, large objects, slow DB queries). These items can be fetched using a profiler tool
Also make sure you're following JMeter Best Practices as it might be the case JMeter is not capable of sending requests fast enough due to either lack of resources on JMeter load generator side or incorrect JMeter configuration (too low heap, running test in GUI mode, using listeners, etc)
When i carryout load testing in jmeter i have list of samples. Each sample returns its own throughput. However in the aggregated graph or summary result it has a total row at the bottom and adds all the throughput. What does this signify?
Can i just use the total throughput as the total throughput of the entire test run. Why does summary report adds up all the sample throughput rather than showing the average throughput?
In the following picture i ran load test with 2 user and 2 ramp up time.
As shown above the total actually sums up the throughput rather than aggregating it.
However, when i carry out test with 1 user and 1 ramp up time then it aggregates the throughput and displays the average throughput of the samplers.
In the below figure i carried out test with 1 thread and 1 ramp up time.
IS this a bug?
No, It's not a bug!!!
The Throughput is the number of requests per unit of time (seconds, minutes, hours) that are sent to your server during the test.
The Throughput is the real load processed by your server (Application under test) during a run but it does not tell you anything about the performance of your server during this same run.
As per JMeter Glossary:
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).
So, In your case For 2 User : The application handled 10.7 requests/second.
And For the Single user : The Application handled 22.9 requests/second.
Its not sums up here, If you see in your screenshot the sum is coming around 14.4/sec, Sot its not sum of all throughput. Its calculated value based on the load you had given and your application would support mentioned throughput.
In your case if a user accesses the application it supports 22.9 requests per sec. But when two users access the application then it supports 10.7 requests per sec.
Please look at here for more info about Jmeter throughput
Jmeter aggregate report total throughput - how is calculated
In case of performance testing, average is something we all avoid.
Going back to actual question. Consider you have 5 requests in one workflow. You are running this test for 50 iterations. So making 250 requests during the load test.
Now you want to analyze individual request performance as well as overall system performance. In this case, when you want to drill down and look at individual request in order to find bottlenecks, you look at the throughput and response time of request.
If you want to find the overall load your system can handle, look at the total throughput.