Merge dea0a33 into 00cc7bd

config.go

@@ -162,8 +162,8 @@ func (cfg Config) Build(opts ...Option) (*Logger, error) {
 	}
 
 	log := New(
-		zapcore.NewCore(enc, sink, cfg.Level),
-		cfg.buildOptions(errSink)...,
+		zapcore.NewCore(enc, zapcore.Lock(sink), cfg.Level),
+		cfg.buildOptions(zapcore.Lock(errSink))...,
 	)
 	if len(opts) > 0 {
 		log = log.WithOptions(opts...)

options.go

@@ -63,7 +63,7 @@ func Fields(fs ...zapcore.Field) Option {
 // safe for concurrent use.
 func ErrorOutput(w zapcore.WriteSyncer) Option {
 	return optionFunc(func(log *Logger) {
-		log.errorOutput = zapcore.Lock(w)
+		log.errorOutput = w
 	})
 }
 

writer.go

@@ -81,5 +81,5 @@ func CombineWriteSyncers(writers ...zapcore.WriteSyncer) zapcore.WriteSyncer {
 	if len(writers) == 0 {
 		return zapcore.AddSync(ioutil.Discard)
 	}
-	return zapcore.Lock(zapcore.NewMultiWriteSyncer(writers...))
+	return zapcore.NewMultiWriteSyncer(writers...)
 }

zapcore/core.go

@@ -61,7 +61,7 @@ func NewCore(enc Encoder, ws WriteSyncer, enab LevelEnabler) Core {
 	return &ioCore{
 		LevelEnabler: enab,
 		enc:          enc,
-		out:          Lock(ws),
+		out:          ws,
 	}
 }