Hello there I made some measures and coroutines loose to par

Question

Hello there I made some measures and coroutines loose to parallelStream when they deal with parallel processing of collection elements It s sad pensive Kotlin v1 3 72

gildor · Answer

It really depends on what kind operation you are doing parallelStream is perfect for CPU intensive non async operations it s directly optimized for it using fork join pool Coroutines also depends what kind coroutines is to control async operations and will not will optimized parallelStream if you just do a bunch of parallel computations which anyway block thread But in general would interesting to see what you particularly your are doing and how you measure

ermac10k · Answer

<https pl kotl in 0Twe1idr4> if you re intersted

gildor · Answer

You have very primitive implementetation of coroutines it s not different from just launching a bunch of threads and join them it s not really a case just a heavy computation on a bunch of threads where you would expect coroutines to win parallelStream Also there are so many things there which are just not equal for example ForkJoinPool used for parallelStreams is not the same as your straight forward dispatcher with Runtime getRuntime availableProcessors

gildor · Answer

And I m not even talking about way how you benchmark it

gildor · Answer

but I still would say parallelPool is perfect for this kind operation run many parallel blocking CPU intensitive operations as efficient as possible

ermac10k · Answer

please show some code to make this implementation of coroutines not so primitive

ermac10k · Answer

i used all that i had found useful in this situation

ermac10k · Answer

it s a bit hard to benchmark spring+kotlin i continue to find a way to do that

gildor · Answer

as I said it depends on your use case

gildor · Answer

if you want to parallel blocking CPU intensive operation just use fork join

gildor · Answer

but if you really have async operations than parallelStream will not work it s purely blocking abstraction this is the case for coroutines

gildor · Answer

coroutines do not add any value for your example just a useless abstraction to run a few threads on a fixed thread pool

gildor · Answer

gt You have very primitive implementetation of coroutines It s really bad explanation not implementation of coroutines but usage of them just as a wrapper on top of thread this would be worse even without coroutines if you would compare it with parallelStream which has own speciailized thread pool with job stealing mechanism

ermac10k · Answer

is it possible to use forkjoinpool as coroutines pool i ve found only fixed single and global ones google keeps silence the fixed one showed the best perfomance global one is a lot worse

gildor · Answer

global you mean GlobalScope

ermac10k · Answer

i mean the way that i don t specified a pool at all

gildor · Answer

Well short answer yes you can use ForkJoinPool commonPool asCoroutineDispatcher

gildor · Answer

gt i mean the way that i don t specified a pool at all Correct because you run by default on DefaultDispatcher which you shouldn t really block and it just doesn t do the same what parallelStream is doing

ermac10k · Answer

woohoo interesting

gildor · Answer

Problem of your example not only in dispatcher it s just looks pointless to use coroutines for what you doing in your example

ermac10k · Answer

yep i see i hoped that it would have been more coroutines than threads in par stream but theese tasks are more cpu bounded than i have expected

gildor · Answer

yep

gildor · Answer

it s fine to use coroutines for this just because it s very convinient even for CPU bound tasks but it makes sense as part of bigger asyncronous code not just to launch a few threads

ermac10k · Answer

convinient in our project we do not use them at all because there is no place for them sob

ermac10k · Answer

i ve tried and lost

gildor · Answer

yes extremely convinient if you have a bunch of asynchronous code

gildor · Answer

if all your code is blocking it would be an improvement in terms of code just because asyncronous code of coroutines look as blocking code which allows to write much more simple non blocking code

ermac10k · Answer

sounds like it s a lot more pythonic async await than golang goroutines

gildor · Answer

it can do both

gildor · Answer

and more natural than async await

ermac10k · Answer

thx continue trying to master them

eHelg · Answer

Not the prettiest proof of concept and somewhat contrived But using the following code I get a difference of about 200ms tops either way Which I would say for most use cases is negligible compared to things such as http calls db access etc <https pl kotl in rRsZs0ETN>

gildor · Answer

Thread pool average duration 192432 Coroutine average duration 147564 Coroutine difference 44868 ns 44 ms

gildor · Answer

See sometimes coroutines are even faster But I would like to point out that you cannot rely on such code as benchmark you need correctly configured benchmark harness which will handle all usual pitfalls of JVM benchmarks

ermac10k · Answer

Thread pool average duration 91329 Coroutine average duration 181858 Coroutine difference 90529 ns 90 ms

ermac10k · Answer

if somebody helps me to set up true benchmark for kotlin+plus spring i cannot start spring app from jmh

gildor · Answer

Why do you need spring in this example at all

ermac10k · Answer

because i m working with it and i wanna benchmark a small piece of an internal process a hibernate query is important to be included in benchmark among others

gildor · Answer

But why You do not measure hybernate

gildor · Answer

Also I still think this comparison is pointless

gildor · Answer

If you want to parallel database requests invest into usage of asynchronous drivers for database it will really help with performance at least in some workloads and it works perfectly with coroutines

gildor · Answer

Also I believe Spring provides support of reactive DB api out of the box and even support coroutines and Flow

ermac10k · Answer

yes i do

ermac10k · Answer

```b findAllByaName it id ``` it s a hiber query

gildor · Answer

If you want to measure performance of database compare it with async api not with blocking

gildor · Answer

I just want to point out that Micro benchmarking is useless if you want to measure such complex system as database you should profile it on application level with close to real life task to cover all possible bottlenecks

ermac10k · Answer

hmpf i benchmarks coroutines against parallesStreams but the impact of db query is important

gildor · Answer

Measuring different implementation one based on pure blocking hybernate and another on something like spring R2DBC

gildor · Answer

ツ

ermac10k · Answer

what

ermac10k · Answer

it s hyber every time

ermac10k · Answer

that s the point

gildor · Answer

It just looks for me that you measuring not what you actually should measure with implementation which shouldn t be used for this case

gildor · Answer

I just want to say that you shouldn t expect some kind improvement in this case coroutines will not make your thread pool run faster just add unnecessary abstraction on top of it

ermac10k · Answer

yep this point i caught yesterday wink