diff options
Diffstat (limited to 'src/runtime/print1.go')
| -rw-r--r-- | src/runtime/print1.go | 30 |
1 files changed, 27 insertions, 3 deletions
diff --git a/src/runtime/print1.go b/src/runtime/print1.go index 8f8268873..3d812bd04 100644 --- a/src/runtime/print1.go +++ b/src/runtime/print1.go @@ -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) { |