Re: How would you go about creating a new Thread Group type?

[Sergio Boso]

Hi,

I fully agree with Robin.
In fact, the "multiple loops scenario" works fine only for development or very 
basic test.

For heavy duty tests I move to Jmeter Plugins with "Stepping Thread Group", that keeps a defined amount of threads running for the 
time you need.

Then the problem moves to feed the threads with the right amount of data... but 
that's another story

regards
Sergio

Il 21/10/2016 19.31, Robin D. Wilson ha scritto:

The behavior I have explained is observed. I see a test run for 10+ minutes 
with 100 threads, then I see the active thread count drop off consistently at 
the end of the test well before I hit the end of the test. If all the threads 
were on the same loop, then the smallest possible number of completed threads 
would be the loop count subtracted from the total threads. (E.g, if there were 
going to be 1 loops for each sampler, I would expect to see the last 
sampler to have at most 9901 incomplete threads when the test begins to wind 
down. But I have observed that the test actually begins to wind down with 8000 
(give or take a few) and then continues to finish running threads until it 
finally completes all 1 loops. This means that there are many threads that 
are not on the last loop when the first thread finishes its last loop.

BUT, when I use the CSV file, I don't see the same behavior. I see what I want 
- which is that I maintain all 100 threads until the number of remaining loops 
passes the '9900'.

Also, your assertion is mistaken, simply because you and I are not apparently 
talking about the same things. A 'thread-loop' is 1 thread running through all 
of the steps in a thread group one time. This is the thing that is taking 10-20 
seconds. And the timing is variable depending on what is going on in the test.

If you want to just simulate the behavior, setup a web page that waits between 
0 and 5 seconds to respond (using a random number generator). Then run a test 
against it with 100 simultaneous threads and 100 loops. You will see what I'm 
talking about.


--
Robin D. Wilson
Voice: 512-426-3929
rwils...@gmail.com

-Original Message-
From: Deepak Goel [mailto:deic...@gmail.com]
Sent: Friday, October 21, 2016 9:09 AM
To: JMeter Users List <user@jmeter.apache.org>
Subject: RE: How would you go about creating a new Thread Group type?

your assumption that the slowest thread takes 20sec and the fastest thread 
takes 10 sec is false. Usually the difference is in milliseconds and over a 
period of time,  it becomes zero. All threads receive their answer in about the 
same time..they have to wait or queue for the same time

On Oct 21, 2016 6:31 PM, "Robin D. Wilson" <rwils...@gmail.com> wrote:


If you have a thread group with 10 HTTP Request samplers in it (or
100, or 1000, whatever the number is - the more you have, the more
pronounced this concern will become), and you run a thread that steps
through each of the samplers in sequence, some threads will get done
sooner than others - that is practically guaranteed - since there is
no way that the server will respond identically quickly to each request.

So, after 1 loop through your test plan you will have a bell curve of
times it took for each thread to complete the loop. A few threads will
have completed relatively fast, a few will have completed relatively
slower, and the bulk of the threads will have completed with times
somewhere in the middle. Let's say that the fastest thread completes
the full set of requests for the loop in 10 seconds. And the slowest
thread completes the loop in 20 seconds. For argument's sake, let's
say that the differential between fastest and slowest is not
necessarily due to the capacity of the server, but just an artifact of
random chance - the fastest thread caught all the green lights, and
the slowest thread caught all the red lights (e.g., i/o blocking, lock waits, 
network congestion back offs, etc.)...

If you re-start the loop for each thread, as soon as it completes the
last loop - then the fast threads will restart much earlier than the
loops that are completing on the slower end of the curve. In fact,
given that the 'fastest' time was only 10 seconds, and the slowest
time was 20 seconds - there is a non-zero chance that the fastest
thread could actually complete another full loop by the time the
slowest thread is completing its first full loop.

If you assign the loops based on a pure division of "number of loops /
number of threads", you will assure that each thread has an equal
number of loops. But you will also assure that some threads complete
their total number of loops well before other threads complete their full set 
of loops.
Moreover, the longer your test run is, the wider the disparity will be
between the threads that reach their full loop count early, and the
threads that finish the full loop count last. Such that, the slower
running threads may be running their last several loops while t

RE: How would you go about creating a new Thread Group type?

[Robin D. Wilson]

The behavior I have explained is observed. I see a test run for 10+ minutes 
with 100 threads, then I see the active thread count drop off consistently at 
the end of the test well before I hit the end of the test. If all the threads 
were on the same loop, then the smallest possible number of completed threads 
would be the loop count subtracted from the total threads. (E.g, if there were 
going to be 1 loops for each sampler, I would expect to see the last 
sampler to have at most 9901 incomplete threads when the test begins to wind 
down. But I have observed that the test actually begins to wind down with 8000 
(give or take a few) and then continues to finish running threads until it 
finally completes all 1 loops. This means that there are many threads that 
are not on the last loop when the first thread finishes its last loop.

BUT, when I use the CSV file, I don't see the same behavior. I see what I want 
- which is that I maintain all 100 threads until the number of remaining loops 
passes the '9900'.

Also, your assertion is mistaken, simply because you and I are not apparently 
talking about the same things. A 'thread-loop' is 1 thread running through all 
of the steps in a thread group one time. This is the thing that is taking 10-20 
seconds. And the timing is variable depending on what is going on in the test. 

If you want to just simulate the behavior, setup a web page that waits between 
0 and 5 seconds to respond (using a random number generator). Then run a test 
against it with 100 simultaneous threads and 100 loops. You will see what I'm 
talking about.


--
Robin D. Wilson
Voice: 512-426-3929
rwils...@gmail.com

-Original Message-
From: Deepak Goel [mailto:deic...@gmail.com] 
Sent: Friday, October 21, 2016 9:09 AM
To: JMeter Users List <user@jmeter.apache.org>
Subject: RE: How would you go about creating a new Thread Group type?

your assumption that the slowest thread takes 20sec and the fastest thread 
takes 10 sec is false. Usually the difference is in milliseconds and over a 
period of time,  it becomes zero. All threads receive their answer in about the 
same time..they have to wait or queue for the same time

On Oct 21, 2016 6:31 PM, "Robin D. Wilson" <rwils...@gmail.com> wrote:

> If you have a thread group with 10 HTTP Request samplers in it (or 
> 100, or 1000, whatever the number is - the more you have, the more 
> pronounced this concern will become), and you run a thread that steps 
> through each of the samplers in sequence, some threads will get done 
> sooner than others - that is practically guaranteed - since there is 
> no way that the server will respond identically quickly to each request.
>
> So, after 1 loop through your test plan you will have a bell curve of 
> times it took for each thread to complete the loop. A few threads will 
> have completed relatively fast, a few will have completed relatively 
> slower, and the bulk of the threads will have completed with times 
> somewhere in the middle. Let's say that the fastest thread completes 
> the full set of requests for the loop in 10 seconds. And the slowest 
> thread completes the loop in 20 seconds. For argument's sake, let's 
> say that the differential between fastest and slowest is not 
> necessarily due to the capacity of the server, but just an artifact of 
> random chance - the fastest thread caught all the green lights, and 
> the slowest thread caught all the red lights (e.g., i/o blocking, lock waits, 
> network congestion back offs, etc.)...
>
> If you re-start the loop for each thread, as soon as it completes the 
> last loop - then the fast threads will restart much earlier than the 
> loops that are completing on the slower end of the curve. In fact, 
> given that the 'fastest' time was only 10 seconds, and the slowest 
> time was 20 seconds - there is a non-zero chance that the fastest 
> thread could actually complete another full loop by the time the 
> slowest thread is completing its first full loop.
>
> If you assign the loops based on a pure division of "number of loops / 
> number of threads", you will assure that each thread has an equal 
> number of loops. But you will also assure that some threads complete 
> their total number of loops well before other threads complete their full set 
> of loops.
> Moreover, the longer your test run is, the wider the disparity will be 
> between the threads that reach their full loop count early, and the 
> threads that finish the full loop count last. Such that, the slower 
> running threads may be running their last several loops while the 
> faster threads have completely died off - meaning that the last few 
> threads will be running while the machine is under a progressively lighter 
> load.
>
> Clearly, you can't help this from happening during the 'last' loop for 
&g

RE: How would you go about creating a new Thread Group type?

[Deepak Goel]

your assumption that the slowest thread takes 20sec and the fastest thread
takes 10 sec is false. Usually the difference is in milliseconds and over a
period of time,  it becomes zero. All threads receive their answer in about
the same time..they have to wait or queue for the same time

On Oct 21, 2016 6:31 PM, "Robin D. Wilson" <rwils...@gmail.com> wrote:

> If you have a thread group with 10 HTTP Request samplers in it (or 100, or
> 1000, whatever the number is - the more you have, the more pronounced this
> concern will become), and you run a thread that steps through each of the
> samplers in sequence, some threads will get done sooner than others - that
> is practically guaranteed - since there is no way that the server will
> respond identically quickly to each request.
>
> So, after 1 loop through your test plan you will have a bell curve of
> times it took for each thread to complete the loop. A few threads will have
> completed relatively fast, a few will have completed relatively slower, and
> the bulk of the threads will have completed with times somewhere in the
> middle. Let's say that the fastest thread completes the full set of
> requests for the loop in 10 seconds. And the slowest thread completes the
> loop in 20 seconds. For argument's sake, let's say that the differential
> between fastest and slowest is not necessarily due to the capacity of the
> server, but just an artifact of random chance - the fastest thread caught
> all the green lights, and the slowest thread caught all the red lights
> (e.g., i/o blocking, lock waits, network congestion back offs, etc.)...
>
> If you re-start the loop for each thread, as soon as it completes the last
> loop - then the fast threads will restart much earlier than the loops that
> are completing on the slower end of the curve. In fact, given that the
> 'fastest' time was only 10 seconds, and the slowest time was 20 seconds -
> there is a non-zero chance that the fastest thread could actually complete
> another full loop by the time the slowest thread is completing its first
> full loop.
>
> If you assign the loops based on a pure division of "number of loops /
> number of threads", you will assure that each thread has an equal number of
> loops. But you will also assure that some threads complete their total
> number of loops well before other threads complete their full set of loops.
> Moreover, the longer your test run is, the wider the disparity will be
> between the threads that reach their full loop count early, and the threads
> that finish the full loop count last. Such that, the slower running threads
> may be running their last several loops while the faster threads have
> completely died off - meaning that the last few threads will be running
> while the machine is under a progressively lighter load.
>
> Clearly, you can't help this from happening during the 'last' loop for
> every thread, since each thread must stop once it has completed a full loop
> - if there are no more loops left to run. But if you don't really care how
> many times each thread runs a loop, you could schedule the loops from a
> queue - where instead of pre-calculating the total loops for each thread,
> you just maintained the total number of loops you needed for the test to
> run, and each thread would just decrement the count when it finished its
> previous loop. Once the count drops all the way to '0', all of the threads
> still running would complete their final loops, and the test would be done.
> BUT no threads would be starting new loops while the server was under a
> lighter load (even though they would complete their last loops while the
> load steadily declined).
>
> Sebb's suggestion of just using a CSV file to count the loops accomplishes
> this exact requirement. If I want a test to run 100,000 loops, I just
> supply a CSV file with 10 records it. Then I set the Thread Group to
> run "Infinite" loops, and set the CSV file to stop on EOF. The test runs
> until the 10th record is retrieved from the CSV file, and once that
> loop starts - the threads all stop when they finish their most recent loop
> because they can't get another record from the CSV. (HINT: you can give the
> CSV variable a name like 'loop_count', and make your CSV file contain
> records that count up from 1-10, and you will also gain a variable that
> tells you which loop you were on for specific sets of requests.)
>
> This isn't a huge concern, just a way to make sure that you maintain the
> same relative server load all through the duration of the test.
>
> --
> Robin D. Wilson
> Voice: 512-426-3929
> rwils...@gmail.com
>
> -Original Message-
> From: Deepak Goel [mailto:deic...@gmail.com]
> Sent: Friday, October 21,

RE: How would you go about creating a new Thread Group type?

[Robin D. Wilson]

If you have a thread group with 10 HTTP Request samplers in it (or 100, or 
1000, whatever the number is - the more you have, the more pronounced this 
concern will become), and you run a thread that steps through each of the 
samplers in sequence, some threads will get done sooner than others - that is 
practically guaranteed - since there is no way that the server will respond 
identically quickly to each request.

So, after 1 loop through your test plan you will have a bell curve of times it 
took for each thread to complete the loop. A few threads will have completed 
relatively fast, a few will have completed relatively slower, and the bulk of 
the threads will have completed with times somewhere in the middle. Let's say 
that the fastest thread completes the full set of requests for the loop in 10 
seconds. And the slowest thread completes the loop in 20 seconds. For 
argument's sake, let's say that the differential between fastest and slowest is 
not necessarily due to the capacity of the server, but just an artifact of 
random chance - the fastest thread caught all the green lights, and the slowest 
thread caught all the red lights (e.g., i/o blocking, lock waits, network 
congestion back offs, etc.)...

If you re-start the loop for each thread, as soon as it completes the last loop 
- then the fast threads will restart much earlier than the loops that are 
completing on the slower end of the curve. In fact, given that the 'fastest' 
time was only 10 seconds, and the slowest time was 20 seconds - there is a 
non-zero chance that the fastest thread could actually complete another full 
loop by the time the slowest thread is completing its first full loop.

If you assign the loops based on a pure division of "number of loops / number 
of threads", you will assure that each thread has an equal number of loops. But 
you will also assure that some threads complete their total number of loops 
well before other threads complete their full set of loops. Moreover, the 
longer your test run is, the wider the disparity will be between the threads 
that reach their full loop count early, and the threads that finish the full 
loop count last. Such that, the slower running threads may be running their 
last several loops while the faster threads have completely died off - meaning 
that the last few threads will be running while the machine is under a 
progressively lighter load.

Clearly, you can't help this from happening during the 'last' loop for every 
thread, since each thread must stop once it has completed a full loop - if 
there are no more loops left to run. But if you don't really care how many 
times each thread runs a loop, you could schedule the loops from a queue - 
where instead of pre-calculating the total loops for each thread, you just 
maintained the total number of loops you needed for the test to run, and each 
thread would just decrement the count when it finished its previous loop. Once 
the count drops all the way to '0', all of the threads still running would 
complete their final loops, and the test would be done. BUT no threads would be 
starting new loops while the server was under a lighter load (even though they 
would complete their last loops while the load steadily declined).

Sebb's suggestion of just using a CSV file to count the loops accomplishes this 
exact requirement. If I want a test to run 100,000 loops, I just supply a CSV 
file with 10 records it. Then I set the Thread Group to run "Infinite" 
loops, and set the CSV file to stop on EOF. The test runs until the 10th 
record is retrieved from the CSV file, and once that loop starts - the threads 
all stop when they finish their most recent loop because they can't get another 
record from the CSV. (HINT: you can give the CSV variable a name like 
'loop_count', and make your CSV file contain records that count up from 
1-10, and you will also gain a variable that tells you which loop you were 
on for specific sets of requests.)

This isn't a huge concern, just a way to make sure that you maintain the same 
relative server load all through the duration of the test.

--
Robin D. Wilson
Voice: 512-426-3929
rwils...@gmail.com

-Original Message-
From: Deepak Goel [mailto:deic...@gmail.com] 
Sent: Friday, October 21, 2016 1:46 AM
To: JMeter Users List <user@jmeter.apache.org>
Subject: Re: How would you go about creating a new Thread Group type?

I am not sure I understand your problem correctly...

Why would the load be reduced to 99 threads? As the threads which haven't 
finished their earlier cycle are still running...they are spending time 
finishing their previous request (which would also indicate a problem with the 
server responding the request)

Hey

Namaskara~Nalama~Guten Tag~Bonjour


   --
Keigu

Deepak
73500 12833
www.simtree.net, dee...@simtree.net
deic...@gmail.com

LinkedIn: www.linkedin.com/in/deicool
Skype: thumsupdeicool
Google talk: deicool
Blog: http://lov

Re: How would you go about creating a new Thread Group type?

[Ivan Rancati]

I'm also not sure I understand the problem.
Assuming I do

1)
use more threads, for example 125, and add a Throughput Controller


2)
There was a similar discussion 3 years ago
http://jmeter.512774.n5.nabble.com/Coordinated-Omission-CO-possible-strategies-tt5718456.html#none

br,
Ivan


On Fri, Oct 21, 2016 at 8:46 AM, Deepak Goel  wrote:

> I am not sure I understand your problem correctly...
>
> Why would the load be reduced to 99 threads? As the threads which haven't
> finished their earlier cycle are still running...they are spending time
> finishing their previous request (which would also indicate a problem with
> the server responding the request)
>
> Hey
>
>

Re: How would you go about creating a new Thread Group type?

[Deepak Goel]

I am not sure I understand your problem correctly...

Why would the load be reduced to 99 threads? As the threads which haven't
finished their earlier cycle are still running...they are spending time
finishing their previous request (which would also indicate a problem with
the server responding the request)

Hey

Namaskara~Nalama~Guten Tag~Bonjour


   --
Keigu

Deepak
73500 12833
www.simtree.net, dee...@simtree.net
deic...@gmail.com

LinkedIn: www.linkedin.com/in/deicool
Skype: thumsupdeicool
Google talk: deicool
Blog: http://loveandfearless.wordpress.com
Facebook: http://www.facebook.com/deicool

"Contribute to the world, environment and more : http://www.gridrepublic.org
"

On Tue, Oct 18, 2016 at 2:38 AM, Robin D. Wilson  wrote:

> Just throwing this out there - to see if anyone wants to lead a code-level
> newbie down the right path. I've been using JMeter for
> 8-9 years now, and really like it. But one thing that bugs me is the way
> the Thread Group works. Specifically, the idea of the
> "loops" bothers me.
>
>
>
> Consider this scenario:
>
>
>
> 1) 100 "users" (e.g., threads)
>
> 2) 10 loops
>
> 3) Test has 10 HTTP Requests in it
>
>
>
> By this logic, you should end up with 100 (users) X 10 loops X 10 HTTP
> Requests = 10,000 requests.
>
>
>
> And you do.
>
>
>
> BUT, what you actually get when you run the test isn't as clear as you
> think. It is basically 100 threads, each running 10 times,
> and each thread loop running 10 HTTP requests in sequence.
>
>
>
> Here's the problem, if thread 1 completes its 10 loops in 100 seconds, but
> threads 2-100 take 200 seconds to complete their 10
> loops. The load will be reduced to only 99 simultaneous threads (users)
> for the last 100 seconds of the test run. That's not a
> 'huge' deal, but it can affect the perception of the test if you look at
> it more like threads 1-50 finish in 100 seconds, and
> threads 51-100 take an extra 100 seconds after that to complete. Then only
> half of your test cycle was at the required 'max' load
> you wanted to create, while the other half was at 50% of the required
> load. (It is reasonably possible that I'm just misinterpreting
> how it actually works, but it appears to work like this from my experience
> since I can see threads continuing to process after some
> threads appear to stop - and it lasts longer than it takes to get through
> the entire cycle - sometimes for several minutes at the
> end of a test run.)
>
>
>
> I'd like to create a new Thread Group that doesn't assign the thread to
> the loop until it starts again at the top of the cycle. So
> if thread-1 finishes really fast, and there are still loops to run - it
> just picks up another loop and runs it. I would always want
> to maintain at least 100 threads executing, so long as there were loops
> left to run. So basically, you multiply the number of loops
> by the number of threads (1000 in my example), and your 100 threads always
> restart until there are no loops left to run. Then the
> longest period you have where you aren't fully loading the servers is just
> the last loop for every thread.
>
>
>
> BUT, I am not 100% sure where I would start in the source code. I have
> programmed before (a long time ago), but if someone could
> point me in the right direction (like, which source files would need to be
> modified, and how would I register my new Thread Group as
> a different option), I think I could figure it out pretty quickly.
>
>
>
> --
>
> Robin D. Wilson
>
>   rwils...@gmail.com
>
>
>
>

Re: How would you go about creating a new Thread Group type?

[Deepak Shetty]

Jmeter-plugins probably has source that you could use to see how they
implemented the various other thread groups (.e.g
https://jmeter-plugins.org/wiki/UltimateThreadGroup/)

On Mon, Oct 17, 2016 at 2:08 PM, Robin D. Wilson  wrote:

> Just throwing this out there - to see if anyone wants to lead a code-level
> newbie down the right path. I've been using JMeter for
> 8-9 years now, and really like it. But one thing that bugs me is the way
> the Thread Group works. Specifically, the idea of the
> "loops" bothers me.
>
>
>
> Consider this scenario:
>
>
>
> 1) 100 "users" (e.g., threads)
>
> 2) 10 loops
>
> 3) Test has 10 HTTP Requests in it
>
>
>
> By this logic, you should end up with 100 (users) X 10 loops X 10 HTTP
> Requests = 10,000 requests.
>
>
>
> And you do.
>
>
>
> BUT, what you actually get when you run the test isn't as clear as you
> think. It is basically 100 threads, each running 10 times,
> and each thread loop running 10 HTTP requests in sequence.
>
>
>
> Here's the problem, if thread 1 completes its 10 loops in 100 seconds, but
> threads 2-100 take 200 seconds to complete their 10
> loops. The load will be reduced to only 99 simultaneous threads (users)
> for the last 100 seconds of the test run. That's not a
> 'huge' deal, but it can affect the perception of the test if you look at
> it more like threads 1-50 finish in 100 seconds, and
> threads 51-100 take an extra 100 seconds after that to complete. Then only
> half of your test cycle was at the required 'max' load
> you wanted to create, while the other half was at 50% of the required
> load. (It is reasonably possible that I'm just misinterpreting
> how it actually works, but it appears to work like this from my experience
> since I can see threads continuing to process after some
> threads appear to stop - and it lasts longer than it takes to get through
> the entire cycle - sometimes for several minutes at the
> end of a test run.)
>
>
>
> I'd like to create a new Thread Group that doesn't assign the thread to
> the loop until it starts again at the top of the cycle. So
> if thread-1 finishes really fast, and there are still loops to run - it
> just picks up another loop and runs it. I would always want
> to maintain at least 100 threads executing, so long as there were loops
> left to run. So basically, you multiply the number of loops
> by the number of threads (1000 in my example), and your 100 threads always
> restart until there are no loops left to run. Then the
> longest period you have where you aren't fully loading the servers is just
> the last loop for every thread.
>
>
>
> BUT, I am not 100% sure where I would start in the source code. I have
> programmed before (a long time ago), but if someone could
> point me in the right direction (like, which source files would need to be
> modified, and how would I register my new Thread Group as
> a different option), I think I could figure it out pretty quickly.
>
>
>
> --
>
> Robin D. Wilson
>
>   rwils...@gmail.com
>
>
>
>

RE: How would you go about creating a new Thread Group type?

[Robin D. Wilson]

The idea with the CSV data set works perfectly. Seems like a good workaround... 
But I'd still like to experiment with building my own Thread Group widget...

--
Robin D. Wilson
Voice: 512-426-3929
rwils...@gmail.com

-Original Message-
From: sebb [mailto:seb...@gmail.com] 
Sent: Monday, October 17, 2016 4:23 PM
To: JMeter Users List <user@jmeter.apache.org>
Subject: Re: How would you go about creating a new Thread Group type?

On 17 October 2016 at 22:08, Robin D. Wilson <rwils...@gmail.com> wrote:
> Just throwing this out there - to see if anyone wants to lead a 
> code-level newbie down the right path. I've been using JMeter for
> 8-9 years now, and really like it. But one thing that bugs me is the 
> way the Thread Group works. Specifically, the idea of the "loops" bothers me.
>
>
>
> Consider this scenario:
>
>
>
> 1) 100 "users" (e.g., threads)
>
> 2) 10 loops
>
> 3) Test has 10 HTTP Requests in it
>
>
>
> By this logic, you should end up with 100 (users) X 10 loops X 10 HTTP 
> Requests = 10,000 requests.
>
>
>
> And you do.
>
>
>
> BUT, what you actually get when you run the test isn't as clear as you 
> think. It is basically 100 threads, each running 10 times, and each thread 
> loop running 10 HTTP requests in sequence.
>
>
>
> Here's the problem, if thread 1 completes its 10 loops in 100 seconds, 
> but threads 2-100 take 200 seconds to complete their 10 loops. The 
> load will be reduced to only 99 simultaneous threads (users) for the 
> last 100 seconds of the test run. That's not a 'huge' deal, but it can 
> affect the perception of the test if you look at it more like threads 
> 1-50 finish in 100 seconds, and threads 51-100 take an extra 100 
> seconds after that to complete. Then only half of your test cycle was 
> at the required 'max' load you wanted to create, while the other half 
> was at 50% of the required load. (It is reasonably possible that I'm 
> just misinterpreting how it actually works, but it appears to work 
> like this from my experience since I can see threads continuing to 
> process after some threads appear to stop - and it lasts longer than 
> it takes to get through the entire cycle - sometimes for several 
> minutes at the end of a test run.)
>
>
>
> I'd like to create a new Thread Group that doesn't assign the thread 
> to the loop until it starts again at the top of the cycle. So if 
> thread-1 finishes really fast, and there are still loops to run - it 
> just picks up another loop and runs it. I would always want to 
> maintain at least 100 threads executing, so long as there were loops left to 
> run. So basically, you multiply the number of loops by the number of threads 
> (1000 in my example), and your 100 threads always restart until there are no 
> loops left to run. Then the longest period you have where you aren't fully 
> loading the servers is just the last loop for every thread.
>

You can probably do this by using a CSV Data set with 1 entries.
Each thread picks the next entry (does not matter what it is) and runs the test 
samples.
When all the entries have been used up, stop the test.

But the normal way to do this is to make sure that the test runs for long 
enough that startup and shutdown variations don't affect the results.

>
> BUT, I am not 100% sure where I would start in the source code. I have 
> programmed before (a long time ago), but if someone could point me in 
> the right direction (like, which source files would need to be modified, and 
> how would I register my new Thread Group as a different option), I think I 
> could figure it out pretty quickly.
>
>
>
> --
>
> Robin D. Wilson
>
>  <mailto:rwils...@gmail.com> rwils...@gmail.com
>
>
>

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Re: How would you go about creating a new Thread Group type?

[sebb]

On 17 October 2016 at 22:08, Robin D. Wilson  wrote:
> Just throwing this out there - to see if anyone wants to lead a code-level 
> newbie down the right path. I've been using JMeter for
> 8-9 years now, and really like it. But one thing that bugs me is the way the 
> Thread Group works. Specifically, the idea of the
> "loops" bothers me.
>
>
>
> Consider this scenario:
>
>
>
> 1) 100 "users" (e.g., threads)
>
> 2) 10 loops
>
> 3) Test has 10 HTTP Requests in it
>
>
>
> By this logic, you should end up with 100 (users) X 10 loops X 10 HTTP 
> Requests = 10,000 requests.
>
>
>
> And you do.
>
>
>
> BUT, what you actually get when you run the test isn't as clear as you think. 
> It is basically 100 threads, each running 10 times,
> and each thread loop running 10 HTTP requests in sequence.
>
>
>
> Here's the problem, if thread 1 completes its 10 loops in 100 seconds, but 
> threads 2-100 take 200 seconds to complete their 10
> loops. The load will be reduced to only 99 simultaneous threads (users) for 
> the last 100 seconds of the test run. That's not a
> 'huge' deal, but it can affect the perception of the test if you look at it 
> more like threads 1-50 finish in 100 seconds, and
> threads 51-100 take an extra 100 seconds after that to complete. Then only 
> half of your test cycle was at the required 'max' load
> you wanted to create, while the other half was at 50% of the required load. 
> (It is reasonably possible that I'm just misinterpreting
> how it actually works, but it appears to work like this from my experience 
> since I can see threads continuing to process after some
> threads appear to stop - and it lasts longer than it takes to get through the 
> entire cycle - sometimes for several minutes at the
> end of a test run.)
>
>
>
> I'd like to create a new Thread Group that doesn't assign the thread to the 
> loop until it starts again at the top of the cycle. So
> if thread-1 finishes really fast, and there are still loops to run - it just 
> picks up another loop and runs it. I would always want
> to maintain at least 100 threads executing, so long as there were loops left 
> to run. So basically, you multiply the number of loops
> by the number of threads (1000 in my example), and your 100 threads always 
> restart until there are no loops left to run. Then the
> longest period you have where you aren't fully loading the servers is just 
> the last loop for every thread.
>

You can probably do this by using a CSV Data set with 1 entries.
Each thread picks the next entry (does not matter what it is) and runs
the test samples.
When all the entries have been used up, stop the test.

But the normal way to do this is to make sure that the test runs for
long enough that startup and shutdown variations don't affect the
results.

>
> BUT, I am not 100% sure where I would start in the source code. I have 
> programmed before (a long time ago), but if someone could
> point me in the right direction (like, which source files would need to be 
> modified, and how would I register my new Thread Group as
> a different option), I think I could figure it out pretty quickly.
>
>
>
> --
>
> Robin D. Wilson
>
>   rwils...@gmail.com
>
>
>

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How would you go about creating a new Thread Group type?

[Robin D. Wilson]

Just throwing this out there - to see if anyone wants to lead a code-level 
newbie down the right path. I've been using JMeter for
8-9 years now, and really like it. But one thing that bugs me is the way the 
Thread Group works. Specifically, the idea of the
"loops" bothers me.

 

Consider this scenario:

 

1) 100 "users" (e.g., threads)

2) 10 loops 

3) Test has 10 HTTP Requests in it

 

By this logic, you should end up with 100 (users) X 10 loops X 10 HTTP Requests 
= 10,000 requests.

 

And you do.

 

BUT, what you actually get when you run the test isn't as clear as you think. 
It is basically 100 threads, each running 10 times,
and each thread loop running 10 HTTP requests in sequence.

 

Here's the problem, if thread 1 completes its 10 loops in 100 seconds, but 
threads 2-100 take 200 seconds to complete their 10
loops. The load will be reduced to only 99 simultaneous threads (users) for the 
last 100 seconds of the test run. That's not a
'huge' deal, but it can affect the perception of the test if you look at it 
more like threads 1-50 finish in 100 seconds, and
threads 51-100 take an extra 100 seconds after that to complete. Then only half 
of your test cycle was at the required 'max' load
you wanted to create, while the other half was at 50% of the required load. (It 
is reasonably possible that I'm just misinterpreting
how it actually works, but it appears to work like this from my experience 
since I can see threads continuing to process after some
threads appear to stop - and it lasts longer than it takes to get through the 
entire cycle - sometimes for several minutes at the
end of a test run.)

 

I'd like to create a new Thread Group that doesn't assign the thread to the 
loop until it starts again at the top of the cycle. So
if thread-1 finishes really fast, and there are still loops to run - it just 
picks up another loop and runs it. I would always want
to maintain at least 100 threads executing, so long as there were loops left to 
run. So basically, you multiply the number of loops
by the number of threads (1000 in my example), and your 100 threads always 
restart until there are no loops left to run. Then the
longest period you have where you aren't fully loading the servers is just the 
last loop for every thread. 

 

BUT, I am not 100% sure where I would start in the source code. I have 
programmed before (a long time ago), but if someone could
point me in the right direction (like, which source files would need to be 
modified, and how would I register my new Thread Group as
a different option), I think I could figure it out pretty quickly.

 

--

Robin D. Wilson

  rwils...@gmail.com