diff --git a/src/Server/Database.cs b/src/Server/Database.cs
index e5616c1..5c73269 100644
--- a/src/Server/Database.cs
+++ b/src/Server/Database.cs
@@ -1,54 +1,87 @@
 using System.Collections.Concurrent;
 
-public class Database
+public class Database : IDisposable
 {
-    private ConcurrentDictionary<string, string> _data = new();
-    private ConcurrentDictionary<string, DateTimeOffset> _ex = new();
+    private readonly ConcurrentDictionary<string, string> _data = new();
+    private readonly ConcurrentDictionary<string, DateTimeOffset> _ex = new();
+    private readonly object _lock = new();
+    private readonly object _cleanLock = new();
+    private CancellationTokenSource _cts = new();
 
-    public Database(long cleanupInterval = 1000)
+    public Database()
     {
-        System.Timers.Timer timer = new(cleanupInterval);
-        timer.Elapsed += (sender, e) => Clean();
-        timer.AutoReset = true;
-        timer.Start();
+        _ = Task.Run(Clean);
     }
 
     public void Set(string key, string value)
     {
-        _data[key] = value;
-        _ex.Remove(key, out _);
+        lock (_lock)
+        {
+            _data[key] = value;
+            _ex.Remove(key, out _);
+        }
     }
 
     public void Set(string key, string value, long ex)
     {
-        _data[key] = value;
-        _ex[key] = DateTimeOffset.UtcNow.AddMilliseconds(ex);
+        lock (_lock)
+        {
+            _data[key] = value;
+            _ex[key] = DateTimeOffset.UtcNow.AddMilliseconds(ex);
+        }
     }
 
     public void Set(string key, long ex)
     {
-        if (_data.ContainsKey(key))
-            _ex[key] = DateTimeOffset.UtcNow.AddMilliseconds(ex);
+        lock (_lock)
+        {
+            if (_data.ContainsKey(key))
+                _ex[key] = DateTimeOffset.UtcNow.AddMilliseconds(ex);
+        }
     }
 
     public void Del(string key)
     {
-        _data.Remove(key, out _);
-        _ex.Remove(key, out _);
+        lock (_lock)
+        {
+            _data.Remove(key, out _);
+            _ex.Remove(key, out _);
+        }
     }
 
     public string? Get(string key)
     {
-        if (_ex.TryGetValue(key, out var expire) && expire < DateTimeOffset.UtcNow)
-            Del(key);
+        lock (_lock)
+        {
+            if (_ex.TryGetValue(key, out var expire) && expire < DateTimeOffset.UtcNow)
+                Del(key);
 
-        return _data.TryGetValue(key, out var value) ? value : null;
+            return _data.TryGetValue(key, out var value) ? value : null;
+        }
     }
 
+    public void Lock() => Monitor.Enter(_cleanLock);
+
+    public void Unlock() => Monitor.Exit(_cleanLock);
+
     private void Clean()
     {
-        foreach (var (key, expire) in _ex)
-            if (expire < DateTimeOffset.UtcNow)
-                Del(key);
+        while (!_cts.Token.IsCancellationRequested)
+        {
+            foreach (var (key, expire) in _ex)
+            {
+                if (expire < DateTimeOffset.UtcNow)
+                    lock (_cleanLock) Del(key);
+            }
+        }
+    }
+
+    public void Dispose()
+    {
+        _cts.Cancel();
+        _cts.Dispose();
+        _data.Clear();
+        _ex.Clear();
+        GC.SuppressFinalize(this);
     }
 }
\ No newline at end of file
diff --git a/src/Server/Program.cs b/src/Server/Program.cs
index b329bee..328c3d6 100644
--- a/src/Server/Program.cs
+++ b/src/Server/Program.cs
@@ -2,6 +2,6 @@
 
 if (args.Length > 0) port = int.Parse(args[0]);
 
-var database = new Database(15000);
+var database = new Database();
 var server = new Server(port, database);
 server.Run();
\ No newline at end of file
diff --git a/tests/Server.UnitTests/Database.cs b/tests/Server.UnitTests/Database.cs
index 5e8e27f..88a315b 100644
--- a/tests/Server.UnitTests/Database.cs
+++ b/tests/Server.UnitTests/Database.cs
@@ -12,7 +12,7 @@ public class DatabaseTests
     [InlineData("", "")]
     public void SetGet(string key, string value)
     {
-        var db = new Database();
+        using var db = new Database();
         db.Set(key, value);
         var result = db.Get(key);
         Assert.Equal(value, result);
@@ -23,7 +23,7 @@ public void SetGet(string key, string value)
     [InlineData("key2", "value", 10)]
     public void SetGetEx(string key, string value, long ex)
     {
-        var db = new Database();
+        using var db = new Database();
         db.Set(key, value, ex);
         var result = db.Get(key);
         Assert.Equal(value, result);
@@ -37,7 +37,7 @@ public void SetGetEx(string key, string value, long ex)
     [Fact]
     public void AutoClean()
     {
-        var db = new Database(10);
+        using var db = new Database();
         db.Set("key1", "value");
         db.Set("key2", "value", 50);
         db.Set("key3", "value", 20);