diff --git a/smart-house/Cargo.toml b/smart-house/Cargo.toml
index e99beb3..d52d949 100644
--- a/smart-house/Cargo.toml
+++ b/smart-house/Cargo.toml
@@ -4,4 +4,4 @@ name = "smart-house"
 version = "0.0.0"
 
 [dependencies]
-tokio = { version = "1.49.0", features = ["rt", "net", "io-util", "time", "sync"] }
+tokio = { version = "1.49.0", features = ["rt", "net", "io-util", "time"] }
diff --git a/smart-house/src/bin/power_socket_client.rs b/smart-house/src/bin/power_socket_client.rs
new file mode 100644
index 0000000..1720a88
--- /dev/null
+++ b/smart-house/src/bin/power_socket_client.rs
@@ -0,0 +1,10 @@
+use smart_house::PowerSocket;
+use std::time::Duration;
+
+fn main() {
+    let mut power_socket = PowerSocket::connect("127.0.0.1:10001");
+    println!("{}", power_socket.display());
+    std::thread::sleep(Duration::from_secs(2));
+    power_socket.set_on(!power_socket.is_on());
+    println!("{}", power_socket.display());
+}
diff --git a/smart-house/src/bin/power_socket_mock.rs b/smart-house/src/bin/power_socket_mock.rs
index 5b64a32..7542edb 100644
--- a/smart-house/src/bin/power_socket_mock.rs
+++ b/smart-house/src/bin/power_socket_mock.rs
@@ -1,5 +1,5 @@
 use std::net::SocketAddr;
-use std::sync::Arc;
+use std::sync::{Arc, RwLock};
 use std::time::Duration;
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
 
@@ -12,7 +12,6 @@ fn parse_args() -> SocketAddr {
         .expect("server address should be valid")
 }
 
-#[derive(Debug)]
 struct RealPowerSocket {
     power_rate: f32,
     on: bool,
@@ -25,7 +24,7 @@ const CMD_GET_POWER: u8 = 4;
 
 const TIMEOUT: Duration = Duration::from_secs(5);
 
-async fn handle_connection(mut socket: tokio::net::TcpStream, real_power_socket: Arc<tokio::sync::RwLock<RealPowerSocket>>) -> Result<(), std::io::Error> {
+async fn handle_connection(mut socket: tokio::net::TcpStream, real_power_socket: Arc<RwLock<RealPowerSocket>>) -> Result<(), std::io::Error> {
     let mut buf = [0u8; 1];
     loop {
         let read = tokio::time::timeout(TIMEOUT, socket.read(&mut buf)).await??;
@@ -36,26 +35,35 @@ async fn handle_connection(mut socket: tokio::net::TcpStream, real_power_socket:
         match buf {
             [CMD_GET_ON] => {
                 println!("handling CMD_GET_ON");
-                let power_socket = real_power_socket.try_read().map_err(|e| std::io::Error::other(e))?;
-                buf = if power_socket.on { [1u8; 1] } else { [0u8; 1] };
+                {
+                    let power_socket = real_power_socket.try_read().map_err(|_| std::io::Error::other("read lock failed"))?;
+                    buf = if power_socket.on { [1u8; 1] } else { [0u8; 1] };
+                }
                 let _ = tokio::time::timeout(TIMEOUT, socket.write(&buf)).await?;
             }
             [CMD_TURN_ON] => {
                 println!("handling CMD_TURN_ON");
-                let mut power_socket = real_power_socket.try_write().map_err(|e| std::io::Error::other(e))?;
-                power_socket.on = true;
+                {
+                    let mut power_socket = real_power_socket.try_write().map_err(|_| std::io::Error::other("write lock failed"))?;
+                    power_socket.on = true;
+                }
                 let _ = tokio::time::timeout(TIMEOUT, socket.write(&buf)).await?;
             }
             [CMD_TURN_OFF] => {
                 println!("handling CMD_TURN_OFF");
-                let mut power_socket = real_power_socket.try_write().map_err(|e| std::io::Error::other(e))?;
-                power_socket.on = false;
+                {
+                    let mut power_socket = real_power_socket.try_write().map_err(|_| std::io::Error::other("write lock failed"))?;
+                    power_socket.on = false;
+                }
                 let _ = tokio::time::timeout(TIMEOUT, socket.write(&buf)).await?;
             }
             [CMD_GET_POWER] => {
                 println!("handling CMD_GET_POWER");
-                let power_socket = real_power_socket.try_read().map_err(|e| std::io::Error::other(e))?;
-                let data_buf = power_socket.power_rate.to_le_bytes();
+                let data_buf: [u8; 4];
+                {
+                    let power_socket = real_power_socket.try_read().map_err(|_| std::io::Error::other("read lock failed"))?;
+                    data_buf = power_socket.power_rate.to_le_bytes();
+                }
                 let _ = tokio::time::timeout(TIMEOUT, socket.write(&data_buf)).await?;
             }
             _ => {
@@ -66,7 +74,7 @@ async fn handle_connection(mut socket: tokio::net::TcpStream, real_power_socket:
 }
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let real_power_socket = Arc::new(tokio::sync::RwLock::new(RealPowerSocket { power_rate: 12.0, on: false }));
+    let real_power_socket = Arc::new(RwLock::new(RealPowerSocket { power_rate: 12.0, on: false }));
     let rt = tokio::runtime::Builder::new_current_thread().enable_all().build()?;
     rt.block_on(async {
         let listener = tokio::net::TcpListener::bind(parse_args()).await?;
diff --git a/smart-house/src/main.rs b/smart-house/src/main.rs
index 1720a88..f328e4d 100644
--- a/smart-house/src/main.rs
+++ b/smart-house/src/main.rs
@@ -1,10 +1 @@
-use smart_house::PowerSocket;
-use std::time::Duration;
-
-fn main() {
-    let mut power_socket = PowerSocket::connect("127.0.0.1:10001");
-    println!("{}", power_socket.display());
-    std::thread::sleep(Duration::from_secs(2));
-    power_socket.set_on(!power_socket.is_on());
-    println!("{}", power_socket.display());
-}
+fn main() {}