Starting and joining a lot of threads slower on AMD systems compared to Intel systems

[Thomas Stüfe]

The difference to J9 is annoying though.

It just occurred to me that we have this handshake between creator thread
and newborn thread. The creator thread waits for the newborn to be up and
running, in order to avoid inconsistent thread states. Which requires the
newborn to get at least some cycles, competing with all its siblings.

I wonder whether J9 does this differently. May be worth looking into.

..Thomas


On Sun, May 16, 2021 at 7:46 AM Aleksey Shipilev <shade at redhat.com> wrote:

> In addition to excellent Thomas Stuefes' reply:
>
> On 5/15/21 10:15 PM, Waishon wrote:
> > In a study project we should create 100.000 threads to get a feeling for
> the time it takes to
> > create a lot of threads and why it's more efficient to use tasks instead.
> I think what you found is in the spirit of the assignment: not only you
> discovered the overheads are
> high, but also that they are different across systems, OSes, etc.
>
> > What might be the reason why starting and joining threads is so much
> slower on AMD systems
> > compared to Intel systems?
> >
> > (Disclaimer: This question was also posted on Stackoverflow, which
> referred to this mailing list:
> >
> https://stackoverflow.com/questions/67550679/creating-threads-is-slower-on-amd-systems-compared-to-intel-systems
> )
> Well, could be a number of things. Most likely, since we are dealing with
> OS syscalls on thread
> creation, we are probably doing mostly memory and task management for new
> threads. But to know more,
> you need to follow the advice of the very first SO comment: "You should
> probably use a profiler and
> it will better tell you where the time is being spent." [1]
>
> For example, with async-profiler [2] would profile both Java, JVM and
> kernel code:
>   $ java
> -agentpath:$asyncProfilerPath/libasyncProfiler.so=start,event=cpu,frequency=10000,file=profile.html
>
> ThreadCreator
>
> --
> Thanks,
> -Aleksey
>
> [1]
>
> https://stackoverflow.com/questions/67550679/creating-threads-is-slower-on-amd-systems-compared-to-intel-systems#comment119397887_67550679
> [2] https://github.com/jvm-profiling-tools/async-profiler
>
>