5x Slower Context Switching Between Fiber-vs-Thread

[Volkan Yazıcı]

It was my pleasure to meet with you all.
I have created a GiST:
https://gist.github.com/vy/c5031a54d42f9e5b855463c838fed6a9
You can just run the file as follows: *java SlowFiberReport.java*

On Tue, Feb 5, 2019 at 9:33 AM Alan Bateman <Alan.Bateman at oracle.com> wrote:

> Nice to meet you at FOSDEM and the OCW.
>
> Can you send me the benchmark, I think the attachment is being stripped
> by the mail servers.
>
> -Alan
>
> On 04/02/2019 21:16, Volkan Yazıcı wrote:
> > Hello,
> >
> > In the attached SlowFiberReport.java, main() calls runThreads() and
> > runFibers() methods and measures the total time it takes. The former,
> > runThreads(), creates 50 threads and passes a token sequentially 1e6
> times.
> > Whereas the latter, runFibers(), creates 50 fibers running on a
> > single-threaded scheduler and again passes a token sequentially 1e6
> times.
> > For synchronization purposes, both approaches use a dedicated Lock and
> > Condition pair for each thread and fiber, respectively. While I am aware
> > that it is still early to assess the performance of Loom, I am surprised
> to
> > see threads performing ~5x better (6s-vs-30s) compared to fibers in terms
> > of basic unmount/mount costs. Would anybody mind helping me to understand
> > the cause of the slowness, please? (I hope I am not doing something brain
> > dead.)
> >
> > Best.
> >
> > *Note:* Using a JDK compiled from 2019-01-20 sources.
>
>