diff --git a/profiler/src/main/java/com/navercorp/pinpoint/profiler/interceptor/bci/JavaAssistByteCodeInstrumentor.java b/profiler/src/main/java/com/navercorp/pinpoint/profiler/interceptor/bci/JavaAssistByteCodeInstrumentor.java
index 6e717a815..64b98c74e 100644
--- a/profiler/src/main/java/com/navercorp/pinpoint/profiler/interceptor/bci/JavaAssistByteCodeInstrumentor.java
+++ b/profiler/src/main/java/com/navercorp/pinpoint/profiler/interceptor/bci/JavaAssistByteCodeInstrumentor.java
@@ -86,10 +86,6 @@ public class JavaAssistByteCodeInstrumentor implements ByteCodeInstrumentor {
         this.retransformEventTrigger = null;
     }
 
-    public JavaAssistByteCodeInstrumentor(Agent agent, InterceptorRegistryBinder interceptorRegistryBinder) {
-        this(agent, interceptorRegistryBinder, null, null);
-    }
-
     public JavaAssistByteCodeInstrumentor(Agent agent, InterceptorRegistryBinder interceptorRegistryBinder, final String bootStrapJar, RetransformEventTrigger retransformEventTrigger) {
         if (interceptorRegistryBinder == null) {
             throw new NullPointerException("interceptorRegistryBinder must not be null");
diff --git a/profiler/src/main/java/com/navercorp/pinpoint/profiler/plugin/JarProfilerPluginClassLoader.java b/profiler/src/main/java/com/navercorp/pinpoint/profiler/plugin/JarProfilerPluginClassLoader.java
index 1842c5fe9..0184a991d 100644
--- a/profiler/src/main/java/com/navercorp/pinpoint/profiler/plugin/JarProfilerPluginClassLoader.java
+++ b/profiler/src/main/java/com/navercorp/pinpoint/profiler/plugin/JarProfilerPluginClassLoader.java
@@ -71,11 +71,16 @@ public class JarProfilerPluginClassLoader implements ProfilerPluginClassLoader {
     }
     
     private final URL pluginJarURL;
+    private final String pluginJarURLExternalForm;
     private final JarFile pluginJar;
     
     
     private JarProfilerPluginClassLoader(URL pluginJarURL, JarFile pluginJar) {
+        if (pluginJarURL == null) {
+            throw new NullPointerException("pluginJarURL must not be null");
+        }
         this.pluginJarURL = pluginJarURL;
+        this.pluginJarURLExternalForm = pluginJarURL.toExternalForm();
         this.pluginJar = pluginJar;
     }
 
@@ -97,18 +102,23 @@ public class JarProfilerPluginClassLoader implements ProfilerPluginClassLoader {
     }
     
     private Class<?> loadFromURLClassLoader(URLClassLoader classLoader, String className) throws IllegalArgumentException, IllegalAccessException, InvocationTargetException, ClassNotFoundException {
-        URL[] urls = classLoader.getURLs();
-        
-        boolean hasPluginJar = false;
-        for (URL url : urls) {
-            if (url.equals(pluginJarURL)) {
-                hasPluginJar = true;
-                break;
+        final URL[] urls = classLoader.getURLs();
+        if (urls != null) {
+
+            boolean hasPluginJar = false;
+            for (URL url : urls) {
+                // if (url.equals(pluginJarURL)) { fix very slow
+                // http://michaelscharf.blogspot.com/2006/11/javaneturlequals-and-hashcode-make.html
+                final String externalForm = url.toExternalForm();
+                if (pluginJarURLExternalForm.equals(externalForm)) {
+                    hasPluginJar = true;
+                    break;
+                }
+            }
+
+            if (!hasPluginJar) {
+                ADD_URL.invoke(classLoader, pluginJarURL);
             }
-        }
-        
-        if (!hasPluginJar) {
-            ADD_URL.invoke(classLoader, pluginJarURL);
         }
         
         return classLoader.loadClass(className);
@@ -128,7 +138,7 @@ public class JarProfilerPluginClassLoader implements ProfilerPluginClassLoader {
         
         try {
             c = classLoader.loadClass(className);
-        } catch (ClassNotFoundException e) {
+        } catch (ClassNotFoundException ignore) {
             
         }
         
diff --git a/profiler/src/main/java/com/navercorp/pinpoint/profiler/sender/SpanStreamUdpSender.java b/profiler/src/main/java/com/navercorp/pinpoint/profiler/sender/SpanStreamUdpSender.java
index ba9088337..0ba786895 100644
--- a/profiler/src/main/java/com/navercorp/pinpoint/profiler/sender/SpanStreamUdpSender.java
+++ b/profiler/src/main/java/com/navercorp/pinpoint/profiler/sender/SpanStreamUdpSender.java
@@ -17,6 +17,7 @@
 package com.navercorp.pinpoint.profiler.sender;
 
 import java.io.IOException;
+import java.net.DatagramSocket;
 import java.net.InetSocketAddress;
 import java.nio.ByteBuffer;
 import java.nio.channels.DatagramChannel;
@@ -103,12 +104,13 @@ public class SpanStreamUdpSender extends AbstractDataSender {
 
     private DatagramChannel createChannel(String host, int port, int timeout, int sendBufferSize) {
         try {
-            DatagramChannel datagramChannel = DatagramChannel.open();
-            datagramChannel.socket().setSoTimeout(timeout);
-            datagramChannel.socket().setSendBufferSize(sendBufferSize);
+            final DatagramChannel datagramChannel = DatagramChannel.open();
+            final DatagramSocket socket = datagramChannel.socket();
+            socket.setSoTimeout(timeout);
+            socket.setSendBufferSize(sendBufferSize);
 
             if (logger.isWarnEnabled()) {
-                final int checkSendBufferSize = datagramChannel.socket().getSendBufferSize();
+                final int checkSendBufferSize = socket.getSendBufferSize();
                 if (sendBufferSize != checkSendBufferSize) {
                     logger.warn("DatagramChannel.setSendBufferSize() error. {}!={}", sendBufferSize, checkSendBufferSize);
                 }
@@ -267,6 +269,7 @@ public class SpanStreamUdpSender extends AbstractDataSender {
                     if (remainingLength != sentBufferSize) {
                         logger.warn("sent buffer {}/{}.", sentBufferSize, remainingLength);
                     } else {
+                        // TODO need check ????
                     }
                        
                 }
diff --git a/rpc/src/main/java/com/navercorp/pinpoint/rpc/util/ListUtils.java b/rpc/src/main/java/com/navercorp/pinpoint/rpc/util/ListUtils.java
index aef2a2ce4..4a67be8e1 100644
--- a/rpc/src/main/java/com/navercorp/pinpoint/rpc/util/ListUtils.java
+++ b/rpc/src/main/java/com/navercorp/pinpoint/rpc/util/ListUtils.java
@@ -84,7 +84,7 @@ public final class ListUtils {
     public static <V> V get(List<V> list, int index, V defaultValue) {
         try {
             return list.get(index);
-        } catch (Exception e) {
+        } catch (Exception ignore) {
         }
 
         return defaultValue;
diff --git a/test/src/main/java/com/navercorp/pinpoint/test/plugin/StreamRedirector.java b/test/src/main/java/com/navercorp/pinpoint/test/plugin/StreamRedirector.java
index 73f2e138e..6717c80e6 100644
--- a/test/src/main/java/com/navercorp/pinpoint/test/plugin/StreamRedirector.java
+++ b/test/src/main/java/com/navercorp/pinpoint/test/plugin/StreamRedirector.java
@@ -40,7 +40,7 @@ public class StreamRedirector implements Runnable {
             while ((read = in.read(buffer)) > 0) {
                 out.write(buffer, 0, read);
             }
-        } catch (IOException e) {
+        } catch (IOException ignore) {
             // do nothing
         }
     }