Thread Locals (was Re: State of Loom)

[Douglas Surber]

One more datapoint on ThreadLocal. I was crawling through a .jfr this morning and found this.

> ThreadLocal$ThreadLocalMap$Entry java.lang.ThreadLocal$ThreadLocalMap.getEntry(ThreadLocal) (JIT Compiled)	4
>    ThreadLocal$ThreadLocalMap$Entry java.lang.ThreadLocal$ThreadLocalMap.access$000(ThreadLocal$ThreadLocalMap, ThreadLocal) (JIT Compiled)	4
>    Object java.lang.ThreadLocal.get() (JIT Compiled)	4
>    ByteBuffer sun.nio.ch.Util.getTemporaryDirectBuffer(int) (JIT Compiled)	4
>    int sun.nio.ch.IOUtil.read(FileDescriptor, ByteBuffer, long, NativeDispatcher) (JIT Compiled)	4
>    int sun.nio.ch.SocketChannelImpl.read(ByteBuffer) (JIT Compiled)	4
> 

Putting a ThreadLocal.get inside SocketChannel.read is surprising and given the condemnation of ThreadLocals in this forum, probably suboptimal.

For what it's worth.

Douglas