HI all,
Error unexpected fault address might be triggered by data race or memory
corruption. After code review, I suspected the reasin is memory corruption
instead
of the data race.
The following code panics occasionally, and yes, when I initialized silces.
package controlcan
import "C"
cReceive := make([]C.struct__CAN_OBJ, 2500)
or
package usbcan
import "controlcan"
pReceive := make([]controlcan.CanObj, 2500)
The error is:
unexpected fault address 0xffffffffffffffff
fatal error: fault
[signal 0xc0000005 code=0x0 addr=0xffffffffffffffff pc=0x41c65d]
goroutine 41 [running]:
runtime.throw(0xcc969a, 0x5)
/usr/local/go/src/runtime/panic.go:619 +0x88 fp=0xc0428ffb38 sp=
0xc0428ffb18 pc=0x42d0b8
runtime.sigpanic()
/usr/local/go/src/runtime/signal_windows.go:170 +0x13a fp=
0xc0428ffb68 sp=0xc0428ffb38 pc=0x43fcca
runtime.gcMarkRootPrepare()
/usr/local/go/src/runtime/mgcmark.go:72 +0x5d fp=0xc0428ffb70 sp=
0xc0428ffb68 pc=0x41c65d
runtime.gcStart(0x0, 0x1, 0x0, 0x0)
/usr/local/go/src/runtime/mgc.go:1350 +0x30f fp=0xc0428ffba0 sp=
0xc0428ffb70 pc=0x419b6f
runtime.mallocgc(0x10000, 0xc54660, 0xc0422ee001, 0xc0423ded60)
/usr/local/go/src/runtime/malloc.go:803 +0x448 fp=0xc0428ffc40 sp=
0xc0428ffba0 pc=0x411c48
runtime.makeslice(0xc54660, 0x9c4, 0x9c4, 0xc04202ce00, 0xc04202c000,
0x411b23)
/usr/local/go/src/runtime/slice.go:61 +0x7e fp=0xc0428ffc70 sp=
0xc0428ffc40 pc=0x43fffe
controlcan.Receive(0x4, 0x0, 0x0, 0xc04267e000, 0x9c4, 0x9c4, 0x64, 0x0, 0x0
, 0x0)
/media/sf_GOPATH0/src/controlcan/controlcan.go:262 +0x75 fp=
0xc0428ffd70 sp=0xc0428ffc70 pc=0xa0d795
posam/protocol/usbcan.(*Channel).receive(0xc04229d490)
/media/sf_GOPATH0/src/posam/protocol/usbcan/usbcan.go:469 +0x536 fp=
0xc0428fffd8 sp=0xc0428ffd70 pc=0xa10926
runtime.goexit()
/usr/local/go/src/runtime/asm_amd64.s:2361 +0x1 fp=0xc0428fffe0 sp=
0xc0428fffd8 pc=0x457531
created by posam/protocol/usbcan.(*Channel).Start
/media/sf_GOPATH0/src/posam/protocol/usbcan/usbcan.go:242 +0x3aa
I got confused for couple of days, until I ran the app with GOGC=off.
Everything works fine except the increasing memory usage. As what Dave
Cheney
said in cgo is not Go <https://dave.cheney.net/2016/01/18/cgo-is-not-go>,
and JimB said at stackoverflow
<https://stackoverflow.com/questions/26203617/golang-panic-fatal-error-from-c-code-unable-to-recover>,
I realize that it is possible
to trigger memory corruption when using cgo. But in the above situation, the
only things required is the type CanObj, not any variables.
So what is the reason behind this error, and how can I play well with GC
and cgo?
Here're links about this question:
- https://github.com/golang/go/issues/30276
-
https://stackoverflow.com/questions/54838040/does-data-race-happen-when-using-cgo
Thank you!
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