• Dmitriy Vyukov's avatar
    runtime: detect deadlocks in programs using cgo · 34c67eb2
    Dmitriy Vyukov authored
    When cgo is used, runtime creates an additional M to handle callbacks on threads not created by Go.
    This effectively disabled deadlock detection, which is a right thing, because Go program can be blocked
    and only serve callbacks on external threads.
    This also disables deadlock detection under race detector, because it happens to use cgo.
    With this change the additional M is created lazily on first cgo call. So deadlock detector
    works for programs that import "C", "net" or "net/http/pprof" but do not use them in fact.
    Also fixes deadlock detector under race detector.
    It should be fine to create the M later, because C code can not call into Go before first cgo call,
    because C code does not know when Go initialization has completed. So a Go program need to call into C
    first either to create an external thread, or notify a thread created in global ctor that Go
    initialization has completed.
    Fixes #4973.
    Fixes #5475.
    
    R=golang-dev, minux.ma, iant
    CC=golang-dev
    https://golang.org/cl/9303046
    34c67eb2
cgocall.c 8.88 KB