Underutilized CPU in Go 1.1 (Windows)

[gopherbot]

by darkgray:

What steps will reproduce the problem?
If possible, include a link to a program on play.golang.org.
1. Compile and run http://play.golang.org/p/VvQYR97vym
2. Observe CPU usage
3. Look puzzled

What is the expected output?
100% utilization on all cores.

What do you see instead?
Bouncing usage averaging around 50-60%.

Which compiler are you using (5g, 6g, 8g, gccgo)?
6g

Which operating system are you using?
Windows 7, 64-bit

Which version are you using?  (run 'go version')
1.1 windows/amd64

Please provide any additional information below.
This is a comparison screenshot of running the above code with 1.0.3 and 1.1 --
http://i.imgur.com/xdhBvM6.png

[dvyukov]

Comment 1:

Labels changed: added performance.

[dvyukov]

Comment 2:

Labels changed: added go1.2, removed priority-triage.

Owner changed to @dvyukov.

Status changed to Accepted.

[btracey]

Comment 3:

I have this same issue with the code in the top comment using go 1.1.1  on Darwin. The
code that I spend most of my time on has gained this issue I believe as of go 1.1, I
think it was fine on 1.0, though I can't be sure because the code is not exactly the
same.

[dvyukov]

Comment 4:

This issue was closed by revision 15a1c3d.

Status changed to Fixed.

[dvyukov]

Comment 5:

This issue was closed by revision 7ebb187.

[dvyukov]

Comment 6:

That last revision actually reverted the fix.

Status changed to Started.

[dvyukov]

Comment 7:

This issue was closed by revision 32fef99.

Status changed to Fixed.

[gopherbot]

Comment 8 by bruce.david.jones:

I am getting this issue with the code provided on Windows 8 64bit. Go version 1.1.2

[dvyukov]

Comment 9:

This will be fixed in Go1.2 release.