Fixed several data races
Fixed several data races

apcera/nats,nats-io/nats,wallyqs/go-nats,nats-io/nats,ZebinKang/go-nats,Lanzafame/nats,dnascimento/nats,apcera/nats,the-control-group/nats,chzyer-dev/nats,nats-io/go-nats,nats-io/go-nats,ZebinKang/go-nats,gale320/nats,aforward/nats,the-control-group/nats,pires/nats,wallyqs/go-nats,dnascimento/nats,ActiveState/nats,pires/nats,wallyqs/nats