cmd/compile: slow compile/build compared to Go 1.4

[kokizzu]

It's been a while, we still use 1.4 because of this issue, it affect to much to our build-test-debug cycle.

$ uname -a
Linux f9988 4.1.14-1-lts #1 SMP Thu Dec 10 21:34:50 CET 2015 x86_64 GNU/Linux

# go 1.1 and go 1.2 failed to compile github.com/yosuke-furukawa/json5/encoding/json5

$ rm -rf $GOPATH/pkg/* 2>1 > /dev/null; go version ; time go build
go version go1.3.3 linux/amd64

CPU: 5.35s      Real: 3.34s     RAM: 287316KB
CPU: 5.63s      Real: 3.40s     RAM: 287316KB
CPU: 5.87s      Real: 3.41s     RAM: 287272KB

$ rm -rf $GOPATH/pkg/* 2>1 > /dev/null; go version ; time go build
go version go1.4.2 linux/amd64

CPU: 5.83s      Real: 3.34s     RAM: 290024KB
CPU: 5.71s      Real: 3.45s     RAM: 290024KB
CPU: 5.96s      Real: 3.46s     RAM: 289948KB

$ rm -rf $GOPATH/pkg/* 2>1 > /dev/null; go version ; time go build
go version go1.5.2 linux/amd64

CPU: 21.93s     Real: 7.92s     RAM: 310148KB
CPU: 21.07s     Real: 7.46s     RAM: 318660KB
CPU: 21.45s     Real: 7.58s     RAM: 310160KB

packages from: http://seblu.net/a/archive/packages/g/go/

for comparison, it's now as slow as gcc-go:

# for comparison:
$ rm -rf $GOPATH/pkg/* 2>1 > /dev/null; go version ; time go build
go version go1.4.2 gccgo (GCC) 5.3.0 linux/amd64

CPU: 20.76s     Real: 9.65s     RAM: 203212KB
CPU: 21.33s     Real: 9.83s     RAM: 203340KB
CPU: 21.09s     Real: 9.85s     RAM: 203336KB

[cespare]

What about after you've installed dependencies? (go build -i or go install)

[kokizzu]

it's significantly faster if not removing the pkg and doing go build -i at the first time..

1.5.2
CPU: 3.03s      Real: 1.99s     RAM: 243676KB
CPU: 3.04s      Real: 1.96s     RAM: 238416KB
CPU: 3.04s      Real: 1.96s     RAM: 238348KB

but still far slower than

1.4.2
CPU: 0.88s      Real: 0.99s     RAM: 207080KB
CPU: 0.93s      Real: 0.99s     RAM: 207000KB
CPU: 0.87s      Real: 1.00s     RAM: 207084KB

[ALTree]

Isn't a 2x slowdown between 1.4 and 1.5 expected? See https://golang.org/doc/go1.5#performance

Builds in Go 1.5 will be slower by a factor of about two

[kokizzu]

it got lot worse on windows 8,1 64-bit, with slower processor but SSD harddisk

1.4.3

$ time go build

real 0m7.670s
user 0m0.015s
sys 0m0.000s

real 0m6.886s
user 0m0.000s
sys 0m0.000s

real 0m7.280s
user 0m0.000s
sys 0m0.000s

1.5.3

real 0m15.825s
user 0m0.000s
sys 0m0.000s

real 0m17.916s
user 0m0.000s
sys 0m0.000s

real 0m16.444s
user 0m0.000s
sys 0m0.000s

[kokizzu]

i got even worse result on Mac OSX 64-bit mid-2012 (i7-3xxx, 16GB, SSD)

$ rm -rf $GOPATH/pkg/* 2>1 > /dev/null; go version ; time go build
go version go1.4.3 darwin/amd64

real    0m43.886s
user    0m45.049s
sys 0m2.789s

[bradfitz]

Much has been done on this in Go 1.7. There will be more in 1.8.

[rsc]

Much has been done on this in Go 1.8. There will be more in 1.9.