What is ramp down time

What is ramp down time?

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Depending on VFD parameters, ramp down times can vary from fractions of a second (when used with dynamic braking) to more than 120 seconds. The ramp-down function is applied in processes that require smooth stops, but also require the process to stop within a given period of time.

How does the Ramp feature work?

The Ramp feature on your device is designed to make the beginning of therapy more comfortable. Ramp time is the period during which the therapy pressure increases from a low start pressure to the prescribed treatment pressure. Ramp time can be set between 5 and 45 …

What is “ramp down” in a project? Ramp down is a slow down (duh). In a manufacturing project it’s when the demand/ forecast for production drops and you consciously produce lesser number of products per week even if this means you’re running your operations below optimal performance/ at low efficiency.

What is the typical MW/minute ramping capability for each ? As far as I know, that capacity is what the reserve provider has committed to dispatch within 10 minutes. Hence, each provider should consider their ability of ramp up (generator) and ramp down

What is the CPAP Ramp Feature?

Ramp Duration This setting determines how long the machine will take to ramp up to the prescribed pressure setting. The default setting for most is 45 minutes, but this can be adjusted according to your comfort. With these two ramp settings, users may have an …

What Is The RAMP Warm UP? The RAMP system thought process can be extended to gym-based sessions. In gym-based sessions a great deal of time is often spent on aerobic-type activities as a warm-up (often on gym-based machines) with little thought given to their productivity away from simply providing a general increase in body temperature. Where space permits, locomotor patterns can be introduced as a Raise …

What is the meaning of ramp up period and loop count in ? Threads corresponds to number of users. If you want your test to launch 100 users simultaneously you can do this by setting up ramp up as 1 second. But in real situations not every 100,000 users logs in at the same point of time, this is where ram

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How to setup ramp down time in gatling?

I have a jmeter scripts to ramp up 20 users over 20 minutes(1 user every minute) and hold for 30 minutes and ramp down 1 user per minute.

How do i achieve this in Gatling?

I tried below setting in gatling,

This ramps up 20 users for 20 minutes and holds for 30 minutes with 20 users. But after that suddenly it drops to zero.

How do I slowly ramp down 1 by 1 user every minute?

1 Answer 1

Note how long your simulation runs is heavily impacted by the scenarios you’re running — all the gatling DSL injection steps control when users get started, and that is all. So if you have scenarios that are very long running or unpredictable, then it’s difficult to guarantee something exactly like what you’ve specified.

In your example

you inject 20 users evenly over 20 minutes (so one every minute). If that is indeed being held for 30 minutes after the ramp then your scenarios are probably looping and the users get stopped by the maxDuration statement.

for a ramp-down, you could change your injection to be

this will give you the same ramping up over 20 minutes, then will keep injecting users as others finish to maintain 20 concurrent users over the next 30 minutes, then gradually slow the rate of injection over the final 20 minutes. However, if your scenario is using loops like .forever to keep running, this ramp-down won’t work as the users injected in the 1st command will never stop.

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JMeter Ramp-Up: The Ultimate Guide

Ramping up and down allows you easily simulate any load pattern and prepare for all the possible cases you might have, so you never see your app go down.

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One of the most critical aspects of performance testing is the ability to mimic a real-life load on your application. But determining the number of concurrent users for the target load isn’t enough. Tested applications could fail in production under the same target load that was used during the test phase. Or, an application could fail under the test load when the problem is a bottleneck in your system. These things happen because, in addition to the target load, developers and performance testers should also care about how the load is distributed during test execution.

What Is Ramping Up in JMeter?

While there are many self-explanatory parameters responsible for load distribution (like the number of threads, loop count, or duration), one of them might not be so simple to understand at first sight, and the appropriate value for this parameter might not always be obvious. This parameter is called ramp-up.

Ramp-up is the amount of time it will take Apache JMeter™ to add all test users (threads) to test execution — or in other words, how long it will take to JMeter to start execution of all the threads.

• 1,000 target threads with 1,000 seconds ramp-up: JMeter will add one user each second.
• 1,000 target threads with 100 seconds ramp-up: JMeter will add 10 users each second.
• 1,000 target threads with 50 seconds ramp-up: JMeter will add 20 users each second.

In this article, we are going to focus on applying JMeter ramp-up usage best practices to mimic different load cases for our application.

Ramping Up Your JMeter Test Scenario

We are going to test our usual http://blazedemo.com/ web app. We will apply various loads with the same target threads value, but with different combinations of ramp-up period. You can also test http://blazedemo.com/.

First of all, we need to create a thread group with the target number of threads (let’s say 100).

Right click > Add > Threads > Thread Group

Change the value of the number of threads to 100. Now, let’s assume that you want to run our test for five minutes. Therefore, you need to specify the value 300 in the Duration field. For now, let’s keep the Ramp-Up Period field in the thread group empty.

2. Add one sample that hits the homepage of tested web application. It will be a GET request to blazedemo.com based on the HTTP protocol.

Right Click on Thread Group > Add >Sampler>HTTP Request

I changed its name to “BlazeDemo home page”. Add “blazedemo.com” as the server name, and make sure the method is set to GET .

It’s useful to see a graph with users distribution. Such a graph helps us visualize the load pattern and check what we are going to test. JMeter doesn’t offer these options out of the box, but you can easily install the Custom plugins package, which contains many useful listeners (installation instruction can be found.

Add>Listener>jp@gc- Active Threads Over Time

Keep in mind that the ramp-up period should not be 0 if you have a large number of target threads. Ramp-up 0 means that performance script will add all the threads at once in the beginning of the test execution, and therefore it will put a very severe load on your application at once.

Of course, sometimes you might want to simulate such load, for example during spike performance tests, but this is a separate case that has a separate best practice approach (and is covered below). But even with spike tests we usually don’t want all users on board in the first second of test execution.

This scenario doesn’t look realistic and usually, such load propagation doesn’t make any sense. If you have a web application, users will usually come to your site more or less gradually and your servers have enough time to adjust and scale appropriately.

Ramp-up distribution should be based on your needs. Therefore, the first thing that needs to be done is to understand your test targets. The best way to do so is to learn and find out your current load patterns from production. But at the same time, in many cases, it’s enough to create a linear ramp-up, which shows users coming gradually to your site or app.

Creating a Linear Load Ramp-Up

Go back to the thread group and change the ramp-up period to 120.

Because the test duration is 300 seconds, ramping-up over two minutes leaves us with three minutes of hold time. It’s important that after the ramp-up is over and all users are up and running, there is enough hold time. Hold time confirms that the system can handle the load and that performance stay stable and don’t deteriorate.

In this test, we decided on three minutes of hold time, but in your case, all these values will be based on your specific needs and that scenario you are going to simulate.

Run the test and see how the number of active users gradually grows for two minutes.

This kind of load called ‘Linear’. This approach works for many users who care mostly about the target load. However, this approach is not the best practice. Why? Because if the server doesn’t perform well under a certain load during the linear ramp-up, it will usually be hard to isolate and determine which load that was. We won’t have a clear idea which load our server can handle and which it can’t.

This is why it is much much better to perform a load by steps. so let’s divide the test duration into stages.

Creating a Stepping Load Ramp-Up

We still want to test 100 users, but we’ll ramp them up them gradually, in steps. We’ll start with 25 users holding a load for a certain period to see how the server handles it. Afterwards, we will add 25 more to get to 50, them another 25 to get to 75, and a final 25 to get to 100 users. This approach works much better and is more reliable.

Unfortunately, JMeter doesn’t support load steps out of the box. But you can easily install the appropriate plugin called Ultimate Thread Group. This plugin gives you very strong control and flexibility over load distribution andis way for you to propagate a load for your application under test.

The Ultimate Thread Group is similar to the default ‘Thread Group’ JMeter element and can be found by:

Right click on elements tab on the left > Add > Threads (Users) > jp@gc — Ultimate Thread Group

After the creation of Ultimate Thread Group element, we can copy our BlazeDemo home page request sampler and Active Threads Over Time listener from the initial Thread Group.

The Ultimate Thread Group provides a Threads Schedule table where you can configure different groups of threads. You can decide on the number of threads (Start Threads Count), the delay before each group will start to be added to the test execution (Initial Delay, sec), the ramp-up period for group (Startup Time, sec), the time to hold the group before ramp-down (Hold Load For, sec) and how fast all the threads of specified group should be turned off (Shutdown Time). All thread groups start at the same time but each one has it’s own Initial Delay value, which helps spin up users from each group separately.

One more great feature of Ultimate Thread Group plugin is that you can see the expected load distribution in the graph below, and tune distribution values according to your needs, even before running the script and without tricky calculations in mind.

Let’s divide our test into four steps adding 25 users each minute. In this case, our Threads Schedule will look like this.

Ramping Up Spike Testing

Another great example of case where such load flexibility might be useful is spike testing. Basically, spike test is a kind of performance test in which application is tested under unexpected increment and decrement of load to see how it behaves in this case and will it be able to handle such spike. Let’s tune our ‘Threads Schedule’ to simulate some kind of spike test. To simulate that pattern we need to use ‘Shutdown Time’ column which is responsible for threads ramp-down.

BlazeMeter also provides ramp-up capabilities, as well as real-time control of thread distribution. Ramp-up and ramp-down are extremely important to mimic the real load on your application. Ramping up and down allows you easily simulate any load pattern you can ever have in production, and to prepare for all the possible cases you might have, so you never see your app go down.

Published at DZone with permission of Yuri Bushnev , DZone MVB . See the original article here.

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What is the difference between Ramp up time and Synchronization timer

`1. No of Threads = 100 Ramp-up time = 20, means every 1 second = 5 requests will be processed. Loop Count =1

1. In the same time: If i will do like below No of Threads = 100 Ramp-up time = 1, Loop Count =1`

And put Synchronization Timer : No of Simulated user to group = 5. In this case as well, J meter process 5 requests at one time.

So what is the different logic between the above 2 concepts.

2 Answers 2

Considering case 1 where the Number of threads = 100, Ramp-up time = 20 and loop count =1. This means that for every one sec 5 threads will be induced. Depending on the time taken for the response the test will run for at least 20 sec or more.

Considering case 2 where the Number of threads = 100, Ramp-up=1, loop count=1 and Adding Synchronization Timer with No of Simulated user to group = 5 A batch of 5 users will be added at once.

Both the tests don’t take the same amount of time to complete.

• In case 1, 5 users are distributed over a period of one sec. i.e. per 0.2 sec one user is added.
• In case 2, 5 users are added to the active thread in one go.

To best understand the difference between the 2 use cases, increase the number of threads to 200 while keeping the remaining parameters as is. Then the difference can be noticed easily.

means every 1 second = 5 requests will be processed. Loop Count =1 — this is wrong, JMeter will start 5 threads each second, the processing time depends on application response time. The concurrency (number of requests at the same moment of time) is not guaranteed

The ramp-up period tells JMeter how long to take to «ramp-up» to the full number of threads chosen. If 10 threads are used, and the ramp-up period is 100 seconds, then JMeter will take 100 seconds to get all 10 threads up and running. Each thread will start 10 (100/10) seconds after the previous thread was begun. If there are 30 threads and a ramp-up period of 120 seconds, then each successive thread will be delayed by 4 seconds.

Ramp-up needs to be long enough to avoid too large a work-load at the start of a test, and short enough that the last threads start running before the first ones finish (unless one wants that to happen).

Start with Ramp-up = number of threads and adjust up or down as needed.

See JMeter Ramp-Up — The Ultimate Guide article for more comprehensive explanation.

Synchronizing Timer guarantees that 5 requests will be executed at the same moment so in your 2nd scenario it would be sending requests in «batches» of 5. Normally people go for Synchronizing Timer to do some form of Spike Testing

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