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runtime: enable/disable SIGPROF if needed when profiling

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This ensures that SIGPROF is handled correctly when using
runtime/pprof in a c-archive or c-shared library.

Separate profiler handling into pre-process changes and per-thread
changes. Simplify the Windows code slightly accordingly.

Fixes #18220.

Change-Id: I5060f7084c91ef0bbe797848978bdc527c312777
Reviewed-on: https://go-review.googlesource.com/34018
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
This commit is contained in:
Ian Lance Taylor 2016-12-06 20:54:41 -08:00
parent 6a29806e01
commit e24228af25
8 changed files with 152 additions and 14 deletions
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41
src/runtime/signal_unix.go
View file

@ -138,6 +138,11 @@ func sigenable(sig uint32) {
return
}
// SIGPROF is handled specially for profiling.
if sig == _SIGPROF {
return
}
t := &sigtable[sig]
if t.flags&_SigNotify != 0 {
ensureSigM()
@ -158,6 +163,11 @@ func sigdisable(sig uint32) {
return
}
// SIGPROF is handled specially for profiling.
if sig == _SIGPROF {
return
}
t := &sigtable[sig]
if t.flags&_SigNotify != 0 {
ensureSigM()
@ -182,6 +192,11 @@ func sigignore(sig uint32) {
return
}
// SIGPROF is handled specially for profiling.
if sig == _SIGPROF {
return
}
t := &sigtable[sig]
if t.flags&_SigNotify != 0 {
atomic.Store(&handlingSig[sig], 0)
@ -189,7 +204,31 @@ func sigignore(sig uint32) {
}
}
func resetcpuprofiler(hz int32) {
// setProcessCPUProfiler is called when the profiling timer changes.
// It is called with prof.lock held. hz is the new timer, and is 0 if
// profiling is being disabled. Enable or disable the signal as
// required for -buildmode=c-archive.
func setProcessCPUProfiler(hz int32) {
if hz != 0 {
// Enable the Go signal handler if not enabled.
if atomic.Cas(&handlingSig[_SIGPROF], 0, 1) {
atomic.Storeuintptr(&fwdSig[_SIGPROF], getsig(_SIGPROF))
setsig(_SIGPROF, funcPC(sighandler))
}
} else {
// If the Go signal handler should be disabled by default,
// disable it if it is enabled.
if !sigInstallGoHandler(_SIGPROF) {
if atomic.Cas(&handlingSig[_SIGPROF], 1, 0) {
setsig(_SIGPROF, atomic.Loaduintptr(&fwdSig[_SIGPROF]))
}
}
}
}
// setThreadCPUProfiler makes any thread-specific changes required to
// implement profiling at a rate of hz.
func setThreadCPUProfiler(hz int32) {
var it itimerval
if hz == 0 {
setitimer(_ITIMER_PROF, &it, nil)