More poor performance from the Open JVM?

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My, expensive, and meant-to-be-fast server became available today and while I would not hesitate to recommend Hetzner – the people I ordered it from, the performance is disappointing.

I don’t think the issue is the box itself – it has 12 cores and 25 GB of RAM. Instead the issue seems to be the code – and I think that means the Open JVM (openjdk jre). If I specify 12 threads to run then performance falls to about 500% (ie the equiavlent of about five cores), if I specify 7 or 8 threads I seem to get peak performance at 600 – 700%. In other words I cannot get out of over a quarter of the silicon.

I think I need to install the Sun/Oracle JVM and see how that runs.