build: dragonflybsd-amd64 random build failure

[timdarbydotnet]

What version of Go are you using (go version)?

Go 1.8

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOHOSTOS="dragonfly"

There is a random recurring build failure for the dragonflybsd builder. An example of this is in the builder log for 22cfe24:

crypto
encoding/base64
reflect
/tmp/workdir-host-dragonfly-amd64-tdfbsd/go/src/reflect/type.go:22:2: can't find import: "unicode"
crypto/sha1
go tool dist: FAILED: /tmp/workdir-host-dragonfly-amd64-tdfbsd/go/pkg/tool/dragonfly_amd64/compile -pack -o /tmp/go-tool-dist-976677949/reflect/go.a -p reflect /tmp/workdir-host-dragonfly-amd64-tdfbsd/go/src/reflect/deepequal.go /tmp/workdir-host-dragonfly-amd64-tdfbsd/go/src/reflect/makefunc.go /tmp/workdir-host-dragonfly-amd64-tdfbsd/go/src/reflect/swapper.go /tmp/workdir-host-dragonfly-amd64-tdfbsd/go/src/reflect/type.go /tmp/workdir-host-dragonfly-amd64-tdfbsd/go/src/reflect/value.go: exit status 2
can't create /tmp/go-tool-dist-976677949/crypto/sha1/go.a: open /tmp/go-tool-dist-976677949/crypto/sha1/go.a: no such file or directory
can't create /tmp/go-tool-dist-976677949/unicode/go.a: open /tmp/go-tool-dist-976677949/unicode/go.a: no such file or directory
can't create /tmp/go-tool-dist-976677949/syscall/go.a: open /tmp/go-tool-dist-976677949/syscall/go.a: no such file or directory

I've been assuming that this was a problem with my build machine, but I'm raising the issue to find out if there's anything I can do to track this down

[ianlancetaylor]

Builder log is at https://build.golang.org/log/30f7def3977874b964826994148eb6d74e155fea .

How many processors does the builder machine have, as reported by runtime.GOMAXPROCS()?

The log doesn't make a lot of sense to me. It seems that /tmp/go-tool-dist-976677949 is disappearing while the build is going on. But even then I don't understand why the reflect package would be built before the unicode package build is complete.

[timdarbydotnet]

GOMAXPROCS is 1

[timdarbydotnet]

Note that two builds after 22cfe24 succeeded, so the random nature of this failure makes it difficult to troubleshoot.

[ianlancetaylor]

If GOMAXPROCS is 1, this is flat out peculiar. It means that the unicode package must have completed building. So how can we see, at the end of the log,

can't create /tmp/go-tool-dist-976677949/unicode/_go_.a: open /tmp/go-tool-dist-976677949/unicode/_go_.a: no such file or directory

[ianlancetaylor]

Hmmm, wait, "unicode" is missing from the dependencies of "reflect" in cmd/dist/deps.go.

[timdarbydotnet]

I see that 127 /tmp/go-tool-dist-* folders are hanging around. Aren't those supposed to be removed?

[ianlancetaylor]

@tdfbsd In the normal course of events, yes. They will be left behind if cmd/dist crashes for some reason.

[ianlancetaylor]

I think I've convinced myself that https://golang.org/cl/55971 will fix the problem. Let's try it and see.

[gopherbot]

Change https://golang.org/cl/55971 mentions this issue: cmd/dist: update deps.go for current dependencies

[gopherbot]

Change https://golang.org/cl/57170 mentions this issue: [release-branch.go1.9] cmd/dist: update deps.go for current dependencies