diff --git a/study/src/main/resources/application.yml b/study/src/main/resources/application.yml
index c152bb20db..e3f03c808a 100644
--- a/study/src/main/resources/application.yml
+++ b/study/src/main/resources/application.yml
@@ -3,8 +3,8 @@ handlebars:
 
 server:
   tomcat:
-    accept-count: 1
-    max-connections: 1
+    accept-count: 2
+    max-connections: 2
     threads:
       min-spare: 2
       max: 2
diff --git a/tomcat/src/main/java/com/techcourse/controller/AbstractController.java b/tomcat/src/main/java/com/techcourse/controller/AbstractController.java
index d91f52d861..9ee8cae097 100644
--- a/tomcat/src/main/java/com/techcourse/controller/AbstractController.java
+++ b/tomcat/src/main/java/com/techcourse/controller/AbstractController.java
@@ -10,9 +10,11 @@ public abstract class AbstractController implements Controller {
     public void service(HttpRequest httpRequest, HttpResponse httpResponse) {
         if (httpRequest.isMethod(HttpMethod.GET)) {
             doGet(httpRequest, httpResponse);
+            return;
         }
         if (httpRequest.isMethod(HttpMethod.POST)) {
             doPost(httpRequest, httpResponse);
+            return;
         }
 
         throw new IllegalArgumentException("유효하지 않은 메소드입니다.");
diff --git a/tomcat/src/main/java/org/apache/catalina/connector/Connector.java b/tomcat/src/main/java/org/apache/catalina/connector/Connector.java
index d171bb84a8..2cf5e9e874 100644
--- a/tomcat/src/main/java/org/apache/catalina/connector/Connector.java
+++ b/tomcat/src/main/java/org/apache/catalina/connector/Connector.java
@@ -4,6 +4,8 @@
 import java.io.UncheckedIOException;
 import java.net.ServerSocket;
 import java.net.Socket;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 import org.apache.coyote.http11.Http11Processor;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -14,16 +16,19 @@ public class Connector implements Runnable {
 
     private static final int DEFAULT_PORT = 8080;
     private static final int DEFAULT_ACCEPT_COUNT = 100;
+    private static final int DEFAULT_MAX_THREADS = 250;
 
     private final ServerSocket serverSocket;
+    private final ExecutorService executor;
     private boolean stopped;
 
     public Connector() {
-        this(DEFAULT_PORT, DEFAULT_ACCEPT_COUNT);
+        this(DEFAULT_PORT, DEFAULT_ACCEPT_COUNT, DEFAULT_MAX_THREADS);
     }
 
-    public Connector(final int port, final int acceptCount) {
+    public Connector(final int port, final int acceptCount, final int maxThreads) {
         this.serverSocket = createServerSocket(port, acceptCount);
+        this.executor = Executors.newFixedThreadPool(maxThreads);
         this.stopped = false;
     }
 
@@ -38,10 +43,8 @@ private ServerSocket createServerSocket(final int port, final int acceptCount) {
     }
 
     public void start() {
-        var thread = new Thread(this);
-        thread.setDaemon(true);
-        thread.start();
         stopped = false;
+        executor.execute(this);
         log.info("Web Application Server started {} port.", serverSocket.getLocalPort());
     }
 
@@ -66,7 +69,7 @@ private void process(final Socket connection) {
             return;
         }
         var processor = new Http11Processor(connection);
-        new Thread(processor).start();
+        executor.execute(processor);
     }
 
     public void stop() {
@@ -75,6 +78,8 @@ public void stop() {
             serverSocket.close();
         } catch (IOException e) {
             log.error(e.getMessage(), e);
+        } finally {
+            executor.shutdown();
         }
     }
 
diff --git a/tomcat/src/main/java/org/apache/coyote/http11/Http11Processor.java b/tomcat/src/main/java/org/apache/coyote/http11/Http11Processor.java
index e623c76679..20e12ff933 100644
--- a/tomcat/src/main/java/org/apache/coyote/http11/Http11Processor.java
+++ b/tomcat/src/main/java/org/apache/coyote/http11/Http11Processor.java
@@ -55,7 +55,6 @@ private HttpResponse createResponse(HttpRequest httpRequest) {
         HttpResponse httpResponse = new HttpResponse();
         try {
             handle(httpRequest, httpResponse);
-            return httpResponse;
         } catch (NotFoundException e) {
             httpResponse.location(httpRequest, NOT_FOUND_PATH);
         } catch (UnauthorizedException e) {
diff --git a/tomcat/src/main/java/org/apache/coyote/http11/httpresponse/HttpResponse.java b/tomcat/src/main/java/org/apache/coyote/http11/httpresponse/HttpResponse.java
index f57c27375f..8d4c448715 100644
--- a/tomcat/src/main/java/org/apache/coyote/http11/httpresponse/HttpResponse.java
+++ b/tomcat/src/main/java/org/apache/coyote/http11/httpresponse/HttpResponse.java
@@ -122,7 +122,8 @@ public byte[] toResponse() {
         StringBuilder stringBuilder = new StringBuilder();
         stringBuilder.append(httpStatusLine.createStatusLineResponse())
                 .append(RESPONSE_LINE_DELIMITER)
-                .append(httpResponseHeader.createHeadersResponse());
+                .append(httpResponseHeader.createHeadersResponse())
+                .append(RESPONSE_LINE_DELIMITER);
         if (httpResponseBody != null) {
             stringBuilder.append(RESPONSE_LINE_DELIMITER)
                     .append(httpResponseBody.getBody());
diff --git a/tomcat/src/main/java/org/apache/coyote/http11/session/Session.java b/tomcat/src/main/java/org/apache/coyote/http11/session/Session.java
index 9054689244..c92567d2ae 100644
--- a/tomcat/src/main/java/org/apache/coyote/http11/session/Session.java
+++ b/tomcat/src/main/java/org/apache/coyote/http11/session/Session.java
@@ -1,8 +1,8 @@
 package org.apache.coyote.http11.session;
 
 import com.techcourse.model.User;
-import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 public class Session {
 
@@ -13,7 +13,7 @@ public class Session {
 
     public Session(String id) {
         this.id = id;
-        this.attributes = new HashMap<>();
+        this.attributes = new ConcurrentHashMap<>();
     }
 
     public boolean hasAttribute(String name) {