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cmd/compile/internal/types: concurrent map read and map write while compiling #21352

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martisch opened this issue Aug 8, 2017 · 9 comments
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cmd/compile/internal/types: concurrent map read and map write while compiling #21352

martisch opened this issue Aug 8, 2017 · 9 comments
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FrozenDueToAge release-blocker
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Go1.9

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@martisch
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martisch commented Aug 8, 2017 •
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one builder failed with what it seems to be a map read / write race during compilation:
https://build.golang.org/log/95ffcbbfdfe3e328d735db12f2127b1dcf1ab17c

at tip 64bd2c4

While the read location seems clear the write location does not seem to be in the trace.
Flake or map in a bad state?

fatal error: concurrent map read and map write

goroutine 15 [running]:
runtime.throw(0x86b5b6e, 0x21)
	/tmp/workdir/go/src/runtime/panic.go:605 +0x7c fp=0x1a121d60 sp=0x1a121d54 pc=0x806f14c
runtime.mapaccess1_faststr(0x86632e0, 0x19866780, 0x86a9cda, 0xd, 0x1)
	/tmp/workdir/go/src/runtime/hashmap_fast.go:213 +0x345 fp=0x1a121d8c sp=0x1a121d60 pc=0x80523b5
cmd/compile/internal/types.(*Pkg).LookupOK(...)
	/tmp/workdir/go/src/cmd/compile/internal/types/pkg.go:85
cmd/compile/internal/types.(*Pkg).Lookup(...)
	/tmp/workdir/go/src/cmd/compile/internal/types/pkg.go:73
cmd/compile/internal/gc.Sysfunc(0x86a9cda, 0xd, 0x199af3b0)
	/tmp/workdir/go/src/cmd/compile/internal/gc/gen.go:15 +0x50 fp=0x1a121dc0 sp=0x1a121d8c pc=0x852b900
cmd/compile/internal/x86.ssaGenValue387(0x1a318120, 0x19efb398)
	/tmp/workdir/go/src/cmd/compile/internal/x86/387.go:123 +0x294 fp=0x1a121e30 sp=0x1a121dc0 pc=0x8625a84
cmd/compile/internal/gc.genssa(0x1a045e00, 0x1a3180f0)
	/tmp/workdir/go/src/cmd/compile/internal/gc/ssa.go:4444 +0x254 fp=0x1a121f90 sp=0x1a121e30 pc=0x85a38e4
cmd/compile/internal/gc.compileSSA(0x19ad4000, 0x3)
	/tmp/workdir/go/src/cmd/compile/internal/gc/pgen.go:242 +0x61 fp=0x1a121fcc sp=0x1a121f90 pc=0x8557e61
cmd/compile/internal/gc.compileFunctions.func2(0x19f55980, 0x19bef280, 0x3)
	/tmp/workdir/go/src/cmd/compile/internal/gc/pgen.go:289 +0x3b fp=0x1a121fe0 sp=0x1a121fcc pc=0x85f2dbb
runtime.goexit()
	/tmp/workdir/go/src/runtime/asm_386.s:1635 +0x1 fp=0x1a121fe4 sp=0x1a121fe0 pc=0x8095f41
created by cmd/compile/internal/gc.compileFunctions
	/tmp/workdir/go/src/cmd/compile/internal/gc/pgen.go:287 +0xeb

goroutine 1 [semacquire]:
sync.runtime_Semacquire(0x19bef28c)
	/tmp/workdir/go/src/runtime/sema.go:56 +0x2e
sync.(*WaitGroup).Wait(0x19bef280)
	/tmp/workdir/go/src/sync/waitgroup.go:131 +0x7b
cmd/compile/internal/gc.compileFunctions()
	/tmp/workdir/go/src/cmd/compile/internal/gc/pgen.go:299 +0x188
cmd/compile/internal/gc.Main(0x86c16a4)
	/tmp/workdir/go/src/cmd/compile/internal/gc/main.go:595 +0x2546
main.main()
	/tmp/workdir/go/src/cmd/compile/main.go:49 +0x7e

goroutine 14 [runnable]:
cmd/compile/internal/types.(*Sym).LinksymName(...)
	/tmp/workdir/go/src/cmd/compile/internal/types/sym.go:73
cmd/compile/internal/types.(*Sym).Linksym(0x1a0dd700, 0x1a0a4120)
	/tmp/workdir/go/src/cmd/compile/internal/types/sym.go:80 +0xb5
cmd/compile/internal/gc.AddrAuto(0x19966a30, 0x19ecd974)
	/tmp/workdir/go/src/cmd/compile/internal/gc/ssa.go:4752 +0x50
cmd/compile/internal/x86.ssaGenValue387(0x1a067fb0, 0x19ecd39c)
	/tmp/workdir/go/src/cmd/compile/internal/x86/387.go:255 +0xf9a
cmd/compile/internal/gc.genssa(0x1a0b5cc0, 0x1a067f80)
	/tmp/workdir/go/src/cmd/compile/internal/gc/ssa.go:4444 +0x254
cmd/compile/internal/gc.compileSSA(0x19ad41a0, 0x2)
	/tmp/workdir/go/src/cmd/compile/internal/gc/pgen.go:242 +0x61
cmd/compile/internal/gc.compileFunctions.func2(0x19f55980, 0x19bef280, 0x2)
	/tmp/workdir/go/src/cmd/compile/internal/gc/pgen.go:289 +0x3b
created by cmd/compile/internal/gc.compileFunctions
	/tmp/workdir/go/src/cmd/compile/internal/gc/pgen.go:287 +0xeb

goroutine 12 [runnable]:
cmd/compile/internal/ssa.(*regAllocState).placeSpills(0x1a2ef110)
	/tmp/workdir/go/src/cmd/compile/internal/ssa/regalloc.go:1666 +0x807
cmd/compile/internal/ssa.(*regAllocState).regalloc(0x1a2ef110, 0x1a05a320)
	/tmp/workdir/go/src/cmd/compile/internal/ssa/regalloc.go:1517 +0x6ace
cmd/compile/internal/ssa.regalloc(0x1a05a320)
	/tmp/workdir/go/src/cmd/compile/internal/ssa/regalloc.go:144 +0x4f
cmd/compile/internal/ssa.Compile(0x1a05a320)
	/tmp/workdir/go/src/cmd/compile/internal/ssa/compile.go:70 +0x244
cmd/compile/internal/gc.buildssa(0x19b969c0, 0x0, 0x0)
	/tmp/workdir/go/src/cmd/compile/internal/gc/ssa.go:212 +0xb0f
cmd/compile/internal/gc.compileSSA(0x19b969c0, 0x0)
	/tmp/workdir/go/src/cmd/compile/internal/gc/pgen.go:240 +0x2d
cmd/compile/internal/gc.compileFunctions.func2(0x19f55980, 0x19bef280, 0x0)
	/tmp/workdir/go/src/cmd/compile/internal/gc/pgen.go:289 +0x3b
created by cmd/compile/internal/gc.compileFunctions
	/tmp/workdir/go/src/cmd/compile/internal/gc/pgen.go:287 +0xeb

/cc @josharian
@ianlancetaylor ianlancetaylor added this to the Go1.10 milestone Aug 8, 2017
@ianlancetaylor
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CC @mdempsky

Would be nice to figure out the cause in case this affects 1.9.

@josharian
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josharian commented Aug 8, 2017 •
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It believe affects 1.9, GO386=387 only. I'll try to send a CL soon.

@gopherbot
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Change https://golang.org/cl/54091 mentions this issue: cmd/compile: unexport gc.Sysfunc

@gopherbot
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Change https://golang.org/cl/54090 mentions this issue: cmd/compile: remove gc.Sysfunc calls from 387 backend

@josharian
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I think CL 54090 should be cherry-picked to 1.9. (Thanks so very much for noticing and filing an issue, @martisch.)

The alternative for 1.9 is to disable concurrent compilation for GO386=387 in cmd/go and cmd/compile, but I think the proper fix is very low risk, perhaps even lower risk than the alternative.

@randall77
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I concur, 54090 should be cherry-picked into 1.9.

@josharian josharian modified the milestones: Go1.9, Go1.10 Aug 9, 2017
@josharian
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Re-opening for cherry-pick to 1.9.

@josharian josharian reopened this Aug 9, 2017
@ianlancetaylor
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CC @broady

gopherbot pushed a commit that referenced this issue Aug 11, 2017
@josharian
cmd/compile: unexport gc.Sysfunc
3b87def 
Updates #21352

Change-Id: If21342f30be32e25840b4072b932a6d4257b420d
Reviewed-on: https://go-review.googlesource.com/54091
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Avelino <t@avelino.xxx>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
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Change https://golang.org/cl/55970 mentions this issue: [release-branch.go1.9] cmd/compile: remove gc.Sysfunc calls from 387 backend

gopherbot pushed a commit that referenced this issue Aug 22, 2017
@josharian @randall77
[release-branch.go1.9] cmd/compile: remove gc.Sysfunc calls from 387 …
9a4e794 
…backend

[This is a cherry-pick of CL 54090 to the 1.9 release branch.]

gc.Sysfunc must not be called concurrently.
We set up runtime routines used by the backend
prior to doing any backend compilation.
I missed the 387 ones; fix that.

Sysfunc should have been unexported during 1.9.
I will rectify that in a subsequent CL.

Fixes #21352

Change-Id: I485bb1867b46d8e5cf64bc820b8963576dc16174
Reviewed-on: https://go-review.googlesource.com/55970
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
@broady broady closed this as completed Aug 22, 2017
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