Netty using 100% CPU

[Rogan Dawes]

(Apologies if this is a duplicate post)

I am writing an app using Netty (4.1.16-Final), that after a while ends up using 100% CPU (on multiple cores, in some cases).

I used VisualVM to try get an idea what was going on, and it showed up as being:

io.netty.channel.nio.SelectedSelectionKeySetSelector.select()

I have attached a screenshot showing a more detailed trace.

Any ideas what could be causing SelectedSelectionKeySetSelector.select() to spin like this?

Thanks!

Rogan

[Nat]

Sounds similar to this issue: https://github.com/netty/netty/issues/2465 Which platform is it? Linux version?

[Rogan Dawes]

Hi Nat,

Thanks for the pointer. It does sound quite similar!

I've experienced the problem on both OS X and Linux, but more prevalent on OS X, I'd say. Next time it happens, I'll try put a breakpoint in that method, and trace it to see what is happening.

Rogan

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[Rogan Dawes]

So the real issue seems to be this one:

https://github.com/netty/netty/issues/7255

I'm using netty 4.1.22.Final on Linux (Ubuntu 16.04, OpenJDK 1.8.0_151).

Rogan

[Nat]

So look like it will be fixed with https://github.com/netty/netty/pull/7801 ?

[Norman Maurer]

Yep that should fix it

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