golang context处理etcd阻塞【简单记录】

使用etcd clientv3中kv的Get、Put等方法若etcd未开启，再进行getTransport时，函数pick会产生阻塞

func (cc *ClientConn) getTransport(ctx context.Context, failfast bool, method string) (transport.ClientTransport, func(balancer.DoneInfo), error) {
	t, done, err := cc.blockingpicker.pick(ctx, failfast, balancer.PickInfo{
		Ctx:            ctx,
		FullMethodName: method,
	})
	if err != nil {
		return nil, nil, toRPCErr(err)
	}
	return t, done, nil
}

// pick returns the transport that will be used for the RPC.
// It may block in the following cases:
// - there's no picker
// - the current picker returns ErrNoSubConnAvailable
// - the current picker returns other errors and failfast is false.
// - the subConn returned by the current picker is not READY
// When one of these situations happens, pick blocks until the picker gets updated.
func (pw *pickerWrapper) pick(ctx context.Context, failfast bool, info balancer.PickInfo) (transport.ClientTransport, func(balancer.DoneInfo), error)

参考etcdclt的代码，需要传入context来进行超时处理

...
ctx, cancel := context.WithTimeout(context.Background(), timeoutSecond*time.Second)
defer cancel()
getResp, err = kv.Get(ctx, action.Key)
...