[dev.power64] code review 160200044: build: merge default into dev.power64

src/pkg/runtime/pprof/pprof.go

 // Copyright 2010 The Go Authors.  All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 // Package pprof writes runtime profiling data in the format expected
 // by the pprof visualization tool.
 // For more information about pprof, see
 // http://code.google.com/p/google-perftools/.
 package pprof
 
@@ skipping 556 matching lines @@
         // but in practice operating systems cannot trigger signals
         // at more than about 500 Hz, and our processing of the
         // signal is not cheap (mostly getting the stack trace).
         // 100 Hz is a reasonable choice: it is frequent enough to
         // produce useful data, rare enough not to bog down the
         // system, and a nice round number to make it easy to
         // convert sample counts to seconds.  Instead of requiring
         // each client to specify the frequency, we hard code it.
         const hz = 100
 
-        // Avoid queueing behind StopCPUProfile.
-        // Could use TryLock instead if we had it.
-        if cpu.profiling {
-                return fmt.Errorf("cpu profiling already in use")
-        }
-
         cpu.Lock()
         defer cpu.Unlock()
         if cpu.done == nil {
                 cpu.done = make(chan bool)
         }
         // Double-check.
         if cpu.profiling {
                 return fmt.Errorf("cpu profiling already in use")
         }
         cpu.profiling = true
@@ skipping 77 matching lines @@
                 }
         }
 
         if tw != nil {
                 tw.Flush()
         }
         return b.Flush()
 }
 
 func runtime_cyclesPerSecond() int64