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[dev.garbage] cmd/gc, runtime: add locks around print statements 

Now each C printf, Go print, or Go println is guaranteed
not to be interleaved with other calls of those functions.
This should help when debugging concurrent failures.

LGTM=rlh
R=rlh
CC=golang-codereviews
https://golang.org/cl/169120043
This commit is contained in:
Russ Cox 2014-11-05 14:42:54 -05:00
parent 91658f934d
commit 75d3f62b3c
8 changed files with 140 additions and 71 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/cmd/gc/builtin.c
View File

@ -24,6 +24,8 @@ char *runtimeimport =
"func @\"\".printslice (? any)\n"
"func @\"\".printnl ()\n"
"func @\"\".printsp ()\n"
"func @\"\".printlock ()\n"
"func @\"\".printunlock ()\n"
"func @\"\".concatstring2 (? string, ? string) (? string)\n"
"func @\"\".concatstring3 (? string, ? string, ? string) (? string)\n"
"func @\"\".concatstring4 (? string, ? string, ? string, ? string) (? string)\n"

1
src/cmd/gc/go.h
View File

@ -1464,6 +1464,7 @@ void walk(Node *fn);
void walkexpr(Node **np, NodeList **init);
void walkexprlist(NodeList *l, NodeList **init);
void walkexprlistsafe(NodeList *l, NodeList **init);
void walkexprlistcheap(NodeList *l, NodeList **init);
void walkstmt(Node **np);
void walkstmtlist(NodeList *l);
Node* conv(Node*, Type*);

2
src/cmd/gc/runtime.go
View File

@ -36,6 +36,8 @@ func printeface(any)
func printslice(any)
func printnl()
func printsp()
func printlock()
func printunlock()
func concatstring2(string, string) string
func concatstring3(string, string, string) string

17
src/cmd/gc/walk.c
View File

@ -363,6 +363,15 @@ walkexprlistsafe(NodeList *l, NodeList **init)
}
}
void
walkexprlistcheap(NodeList *l, NodeList **init)
{
for(; l; l=l->next) {
l->n = cheapexpr(l->n, init);
walkexpr(&l->n, init);
}
}
void
walkexpr(Node **np, NodeList **init)
{
@ -1773,6 +1782,11 @@ walkprint(Node *nn, NodeList **init)
calls = nil;
notfirst = 0;
// Hoist all the argument evaluation up before the lock.
walkexprlistcheap(all, init);
calls = list(calls, mkcall("printlock", T, init));
for(l=all; l; l=l->next) {
if(notfirst) {
calls = list(calls, mkcall("printsp", T, init));
@ -1853,6 +1867,9 @@ walkprint(Node *nn, NodeList **init)
if(op == OPRINTN)
calls = list(calls, mkcall("printnl", T, nil));
calls = list(calls, mkcall("printunlock", T, init));
typechecklist(calls, Etop);
walkexprlist(calls, init);

30
src/runtime/print1.go
View File

@ -41,7 +41,31 @@ func snprintf(dst *byte, n int32, s *byte) {
gp.writebuf = nil
}
//var debuglock mutex
var debuglock mutex
// The compiler emits calls to printlock and printunlock around
// the multiple calls that implement a single Go print or println
// statement. Some of the print helpers (printsp, for example)
// call print recursively. There is also the problem of a crash
// happening during the print routines and needing to acquire
// the print lock to print information about the crash.
// For both these reasons, let a thread acquire the printlock 'recursively'.
func printlock() {
mp := getg().m
mp.printlock++
if mp.printlock == 1 {
lock(&debuglock)
}
}
func printunlock() {
mp := getg().m
mp.printlock--
if mp.printlock == 0 {
unlock(&debuglock)
}
}
// write to goroutine-local buffer if diverting output,
// or else standard error.
@ -80,7 +104,7 @@ func printnl() {
// Very simple printf. Only for debugging prints.
// Do not add to this without checking with Rob.
func vprintf(str string, arg unsafe.Pointer) {
//lock(&debuglock);
printlock()
s := bytes(str)
start := 0
@ -160,7 +184,7 @@ func vprintf(str string, arg unsafe.Pointer) {
gwrite(s[start:i])
}
//unlock(&debuglock);
printunlock()
}
func printpc(p unsafe.Pointer) {

1
src/runtime/runtime.h
View File

@ -345,6 +345,7 @@ struct M
int32 helpgc;
bool spinning; // M is out of work and is actively looking for work
bool blocked; // M is blocked on a Note
int8 printlock;
uint32 fastrand;
uint64 ncgocall; // number of cgo calls in total
int32 ncgo; // number of cgo calls currently in progress

152
test/live.go
View File

@ -9,20 +9,39 @@
package main
func printnl()
//go:noescape
func printpointer(**int)
//go:noescape
func printintpointer(*int)
//go:noescape
func printstringpointer(*string)
//go:noescape
func printstring(string)
//go:noescape
func printbytepointer(*byte)
func printint(int)
func f1() {
var x *int
print(&x) // ERROR "live at call to printpointer: x$"
print(&x) // ERROR "live at call to printpointer: x$"
printpointer(&x) // ERROR "live at call to printpointer: x$"
printpointer(&x) // ERROR "live at call to printpointer: x$"
}
func f2(b bool) {
if b {
print(0) // nothing live here
printint(0) // nothing live here
return
}
var x *int
print(&x) // ERROR "live at call to printpointer: x$"
print(&x) // ERROR "live at call to printpointer: x$"
printpointer(&x) // ERROR "live at call to printpointer: x$"
printpointer(&x) // ERROR "live at call to printpointer: x$"
}
func f3(b bool) {
@ -30,22 +49,22 @@ func f3(b bool) {
// live throughout the function, to avoid being poisoned
// in GODEBUG=gcdead=1 mode.
print(0) // ERROR "live at call to printint: x y$"
printint(0) // ERROR "live at call to printint: x y$"
if b == false {
print(0) // ERROR "live at call to printint: x y$"
printint(0) // ERROR "live at call to printint: x y$"
return
}
if b {
var x *int
print(&x) // ERROR "live at call to printpointer: x y$"
print(&x) // ERROR "live at call to printpointer: x y$"
printpointer(&x) // ERROR "live at call to printpointer: x y$"
printpointer(&x) // ERROR "live at call to printpointer: x y$"
} else {
var y *int
print(&y) // ERROR "live at call to printpointer: x y$"
print(&y) // ERROR "live at call to printpointer: x y$"
printpointer(&y) // ERROR "live at call to printpointer: x y$"
printpointer(&y) // ERROR "live at call to printpointer: x y$"
}
print(0) // ERROR "live at call to printint: x y$" "x \(type \*int\) is ambiguously live" "y \(type \*int\) is ambiguously live"
printint(0) // ERROR "live at call to printint: x y$" "x \(type \*int\) is ambiguously live" "y \(type \*int\) is ambiguously live"
}
// The old algorithm treated x as live on all code that
@ -56,20 +75,20 @@ func f3(b bool) {
func f4(b1, b2 bool) { // x not live here
if b2 {
print(0) // x not live here
printint(0) // x not live here
return
}
var z **int
x := new(int)
*x = 42
z = &x
print(**z) // ERROR "live at call to printint: x z$"
printint(**z) // ERROR "live at call to printint: x z$"
if b2 {
print(1) // ERROR "live at call to printint: x$"
printint(1) // ERROR "live at call to printint: x$"
return
}
for {
print(**z) // ERROR "live at call to printint: x z$"
printint(**z) // ERROR "live at call to printint: x z$"
}
}
@ -84,7 +103,7 @@ func f5(b1 bool) {
*y = 54
z = &y
}
print(**z) // ERROR "live at call to printint: x y$" "x \(type \*int\) is ambiguously live" "y \(type \*int\) is ambiguously live"
printint(**z) // ERROR "live at call to printint: x y$" "x \(type \*int\) is ambiguously live" "y \(type \*int\) is ambiguously live"
}
// confusion about the _ result used to cause spurious "live at entry to f6: _".
@ -155,8 +174,8 @@ func f11b() *int {
// At this point p is dead: the code here cannot
// get to the bottom of the function.
// This used to have a spurious "live at call to printint: p".
print(1) // nothing live here!
select { // ERROR "live at call to newselect: autotmp" "live at call to selectgo: autotmp"
printint(1) // nothing live here!
select { // ERROR "live at call to newselect: autotmp" "live at call to selectgo: autotmp"
case <-c: // ERROR "live at call to selectrecv: autotmp"
return nil
case <-c: // ERROR "live at call to selectrecv: autotmp"
@ -172,8 +191,8 @@ func f11c() *int {
if b {
// Unlike previous, the cases in this select fall through,
// so we can get to the println, so p is not dead.
print(1) // ERROR "live at call to printint: p"
select { // ERROR "live at call to newselect: autotmp.* p" "live at call to selectgo: autotmp.* p"
printint(1) // ERROR "live at call to printint: p"
select { // ERROR "live at call to newselect: autotmp.* p" "live at call to selectgo: autotmp.* p"
case <-c: // ERROR "live at call to selectrecv: autotmp.* p"
case <-c: // ERROR "live at call to selectrecv: autotmp.* p"
}
@ -209,7 +228,7 @@ func h13(string, string) string
func f14() {
x := g14()
print(&x) // ERROR "live at call to printpointer: x"
printstringpointer(&x) // ERROR "live at call to printstringpointer: x"
}
func g14() string
@ -217,8 +236,8 @@ func g14() string
func f15() {
var x string
_ = &x
x = g15() // ERROR "live at call to g15: x"
print(x) // ERROR "live at call to printstring: x"
x = g15() // ERROR "live at call to g15: x"
printstring(x) // ERROR "live at call to printstring: x"
}
func g15() string
@ -282,7 +301,7 @@ func f18() {
}
z = m2[g18()] // ERROR "live at call to mapaccess1: autotmp_[0-9]+$"
z = m2[g18()] // ERROR "live at call to mapaccess1: autotmp_[0-9]+$"
print(z)
printbytepointer(z)
}
var ch chan *byte
@ -296,7 +315,7 @@ func f19() {
}
z = <-ch // ERROR "live at call to chanrecv1: autotmp_[0-9]+$"
z = <-ch // ERROR "live at call to chanrecv1: autotmp_[0-9]+$"
print(z)
printbytepointer(z)
}
func f20() {
@ -316,7 +335,7 @@ func f21() {
}
z = m2[[2]string{"x", "y"}] // ERROR "live at call to mapaccess1: autotmp_[0-9]+$"
z = m2[[2]string{"x", "y"}] // ERROR "live at call to mapaccess1: autotmp_[0-9]+$"
print(z)
printbytepointer(z)
}
func f23() {
@ -328,7 +347,8 @@ func f23() {
}
z, ok = m2[[2]string{"x", "y"}] // ERROR "live at call to mapaccess2: autotmp_[0-9]+$"
z, ok = m2[[2]string{"x", "y"}] // ERROR "live at call to mapaccess2: autotmp_[0-9]+$"
print(z, ok)
printbytepointer(z)
print(ok)
}
func f24() {
@ -350,8 +370,8 @@ func f25(b bool) {
}
var x string
_ = &x
x = g15() // ERROR "live at call to g15: x"
print(x) // ERROR "live at call to printstring: x"
x = g15() // ERROR "live at call to g15: x"
printstring(x) // ERROR "live at call to printstring: x"
} // ERROR "live at call to deferreturn: x"
func g25()
@ -366,7 +386,7 @@ func f26(b bool) {
}
print26((*int)(nil), (*int)(nil), (*int)(nil)) // ERROR "live at call to print26: autotmp_[0-9]+$"
print26((*int)(nil), (*int)(nil), (*int)(nil)) // ERROR "live at call to print26: autotmp_[0-9]+$"
println()
printnl()
}
//go:noescape
@ -381,7 +401,7 @@ func f27(b bool) {
}
call27(func() { x++ }) // ERROR "live at call to call27: autotmp_[0-9]+$"
call27(func() { x++ }) // ERROR "live at call to call27: autotmp_[0-9]+$"
println()
printnl()
}
// but defer does escape to later execution in the function
@ -392,7 +412,7 @@ func f27defer(b bool) {
defer call27(func() { x++ }) // ERROR "live at call to deferproc: autotmp_[0-9]+$" "live at call to deferreturn: autotmp_[0-9]+$"
}
defer call27(func() { x++ }) // ERROR "live at call to deferproc: autotmp_[0-9]+ autotmp_[0-9]+$" "live at call to deferreturn: autotmp_[0-9]+ autotmp_[0-9]+$" "ambiguously live"
println() // ERROR "live at call to printnl: autotmp_[0-9]+ autotmp_[0-9]+$"
printnl() // ERROR "live at call to printnl: autotmp_[0-9]+ autotmp_[0-9]+$"
} // ERROR "live at call to deferreturn: autotmp_[0-9]+ autotmp_[0-9]+$"
// and newproc (go) escapes to the heap
@ -403,7 +423,7 @@ func f27go(b bool) {
go call27(func() { x++ }) // ERROR "live at call to newobject: &x" "live at call to newproc: &x$"
}
go call27(func() { x++ }) // ERROR "live at call to newobject: &x"
println()
printnl()
}
//go:noescape
@ -415,10 +435,10 @@ var s1, s2, s3, s4, s5, s6, s7, s8, s9, s10 string
func f28(b bool) {
if b {
print(s1 + s2 + s3 + s4 + s5 + s6 + s7 + s8 + s9 + s10) // ERROR "live at call to concatstrings: autotmp_[0-9]+$" "live at call to printstring: autotmp_[0-9]+$"
printstring(s1 + s2 + s3 + s4 + s5 + s6 + s7 + s8 + s9 + s10) // ERROR "live at call to concatstrings: autotmp_[0-9]+$" "live at call to printstring: autotmp_[0-9]+$"
}
print(s1 + s2 + s3 + s4 + s5 + s6 + s7 + s8 + s9 + s10) // ERROR "live at call to concatstrings: autotmp_[0-9]+$" "live at call to printstring: autotmp_[0-9]+$"
print(s1 + s2 + s3 + s4 + s5 + s6 + s7 + s8 + s9 + s10) // ERROR "live at call to concatstrings: autotmp_[0-9]+$" "live at call to printstring: autotmp_[0-9]+$"
printstring(s1 + s2 + s3 + s4 + s5 + s6 + s7 + s8 + s9 + s10) // ERROR "live at call to concatstrings: autotmp_[0-9]+$" "live at call to printstring: autotmp_[0-9]+$"
printstring(s1 + s2 + s3 + s4 + s5 + s6 + s7 + s8 + s9 + s10) // ERROR "live at call to concatstrings: autotmp_[0-9]+$" "live at call to printstring: autotmp_[0-9]+$"
}
// map iterator should die on end of range loop
@ -426,14 +446,14 @@ func f28(b bool) {
func f29(b bool) {
if b {
for k := range m { // ERROR "live at call to mapiterinit: autotmp_[0-9]+$" "live at call to mapiternext: autotmp_[0-9]+$"
print(k) // ERROR "live at call to printstring: autotmp_[0-9]+$"
printstring(k) // ERROR "live at call to printstring: autotmp_[0-9]+$"
}
}
for k := range m { // ERROR "live at call to mapiterinit: autotmp_[0-9]+$" "live at call to mapiternext: autotmp_[0-9]+$"
print(k) // ERROR "live at call to printstring: autotmp_[0-9]+$"
printstring(k) // ERROR "live at call to printstring: autotmp_[0-9]+$"
}
for k := range m { // ERROR "live at call to mapiterinit: autotmp_[0-9]+$" "live at call to mapiternext: autotmp_[0-9]+$"
print(k) // ERROR "live at call to printstring: autotmp_[0-9]+$"
printstring(k) // ERROR "live at call to printstring: autotmp_[0-9]+$"
}
}
@ -446,14 +466,14 @@ func f30(b bool) {
// the copy of ptrarr and the internal iterator pointer.
if b {
for _, p := range ptrarr {
print(p) // ERROR "live at call to printpointer: autotmp_[0-9]+ autotmp_[0-9]+$"
printintpointer(p) // ERROR "live at call to printintpointer: autotmp_[0-9]+ autotmp_[0-9]+$"
}
}
for _, p := range ptrarr {
print(p) // ERROR "live at call to printpointer: autotmp_[0-9]+ autotmp_[0-9]+$"
printintpointer(p) // ERROR "live at call to printintpointer: autotmp_[0-9]+ autotmp_[0-9]+$"
}
for _, p := range ptrarr {
print(p) // ERROR "live at call to printpointer: autotmp_[0-9]+ autotmp_[0-9]+$"
printintpointer(p) // ERROR "live at call to printintpointer: autotmp_[0-9]+ autotmp_[0-9]+$"
}
}
@ -503,44 +523,44 @@ var m33 map[interface{}]int
func f33() {
if m33[nil] == 0 { // ERROR "live at call to mapaccess1: autotmp_[0-9]+$"
println()
printnl()
return
} else {
println()
printnl()
}
println()
printnl()
}
func f34() {
if m33[nil] == 0 { // ERROR "live at call to mapaccess1: autotmp_[0-9]+$"
println()
printnl()
return
}
println()
printnl()
}
func f35() {
if m33[nil] == 0 && m33[nil] == 0 { // ERROR "live at call to mapaccess1: autotmp_[0-9]+$"
println()
printnl()
return
}
println()
printnl()
}
func f36() {
if m33[nil] == 0 || m33[nil] == 0 { // ERROR "live at call to mapaccess1: autotmp_[0-9]+$"
println()
printnl()
return
}
println()
printnl()
}
func f37() {
if (m33[nil] == 0 || m33[nil] == 0) && m33[nil] == 0 { // ERROR "live at call to mapaccess1: autotmp_[0-9]+$"
println()
printnl()
return
}
println()
printnl()
}
// select temps should disappear in the case bodies
@ -558,44 +578,44 @@ func f38(b bool) {
if b {
select { // ERROR "live at call"
case <-fc38(): // ERROR "live at call"
println()
printnl()
case fc38() <- *fi38(1): // ERROR "live at call"
println()
printnl()
case *fi38(2) = <-fc38(): // ERROR "live at call"
println()
printnl()
case *fi38(3), *fb38() = <-fc38(): // ERROR "live at call"
println()
printnl()
}
println()
printnl()
}
println()
printnl()
}
// issue 8097: mishandling of x = x during return.
func f39() (x []int) {
x = []int{1}
println() // ERROR "live at call to printnl: x"
printnl() // ERROR "live at call to printnl: x"
return x
}
func f39a() (x []int) {
x = []int{1}
println() // ERROR "live at call to printnl: x"
printnl() // ERROR "live at call to printnl: x"
return
}
func f39b() (x [10]*int) {
x = [10]*int{}
x[0] = new(int) // ERROR "live at call to newobject: x"
println() // ERROR "live at call to printnl: x"
printnl() // ERROR "live at call to printnl: x"
return x
}
func f39c() (x [10]*int) {
x = [10]*int{}
x[0] = new(int) // ERROR "live at call to newobject: x"
println() // ERROR "live at call to printnl: x"
printnl() // ERROR "live at call to printnl: x"
return
}
@ -614,7 +634,7 @@ func newT40() *T40 {
func bad40() {
t := newT40()
println()
printnl()
_ = t
}
@ -622,6 +642,6 @@ func good40() {
ret := T40{}
ret.m = make(map[int]int) // ERROR "live at call to makemap: ret"
t := &ret
println() // ERROR "live at call to printnl: ret"
printnl() // ERROR "live at call to printnl: ret"
_ = t
}

6
test/live2.go
View File

@ -12,6 +12,8 @@ package main
// issue 8142: lost 'addrtaken' bit on inlined variables.
// no inlining in this test, so just checking that non-inlined works.
func printnl()
type T40 struct {
m map[int]int
}
@ -24,7 +26,7 @@ func newT40() *T40 {
func bad40() {
t := newT40() // ERROR "live at call to makemap: ret"
println() // ERROR "live at call to printnl: ret"
printnl() // ERROR "live at call to printnl: ret"
_ = t
}
@ -32,6 +34,6 @@ func good40() {
ret := T40{}
ret.m = make(map[int]int) // ERROR "live at call to makemap: ret"
t := &ret
println() // ERROR "live at call to printnl: ret"
printnl() // ERROR "live at call to printnl: ret"
_ = t
}