Thread-Local Handshakes slowdown on single-cpu machines

[David Holmes]

Hi Miklos,

On 28/04/2020 7:26 am, Karakó Miklós wrote:
> Hello,
> 
> We bumped into a possible Thread-Local Handshakes issue with multiple 
> apps. It seems that enabled TLH slows down applications running on 
> (although rare) single CPU boxes. I would be grateful if you could 
> confirm that this is a known trade-off for these rare setups or a 
> possible JVM bug. That would save us at least a few hours of debugging.
> 
> TL;DR: Both tested apps stop frequently around "HandshakeOneThread", 
> "HandshakeAllThreads" and "Revoked bias of currently-unlocked object" 
> running with OpenJDK12/OpenJDK13/OpenJDK14. OpenJDK 13 with 
> -XX:-ThreadLocalHandshakes fixes the issue. Adding a second CPU to the 
> virtual machine fixes the issue. Enabling hyper-threading fixes the issue.

Can you try with latest JDK 15 build, just to see if this may be 
something already addressed?

Thanks,
David

> More details are available at StackOverflow: 
> https://stackoverflow.com/questions/61375565/slow-application-frequent-jvm-hangs-with-single-cpu-setups-and-java-12 
> 
> 
> All thoughts are welcome.
> 
> Best,
> Miklos
>