Fixed send retry policy in TCPDataSender
Retry policy in TCPDataSender is not working properly, so Fixed it. 

profiler/src/main/java/com/navercorp/pinpoint/profiler/sender/RetryMessage.java
profiler/src/main/java/com/navercorp/pinpoint/profiler/sender/RetryMessage.java
diff --git a/profiler/src/main/java/com/navercorp/pinpoint/profiler/sender/RetryMessage.java b/profiler/src/main/java/com/navercorp/pinpoint/profiler/sender/RetryMessage.java
index 13ef7c3ac506..09c98d0a3067 100644
--- a/profiler/src/main/java/com/navercorp/pinpoint/profiler/sender/RetryMessage.java
+++ b/profiler/src/main/java/com/navercorp/pinpoint/profiler/sender/RetryMessage.java
@@ -16,6 +16,7 @@
 
 package com.navercorp.pinpoint.profiler.sender;
 
+import org.apache.commons.lang.ArrayUtils;
 import org.apache.commons.lang.StringUtils;
 
 /**
@@ -80,12 +81,12 @@ public int fail() {
 
     @Override
     public String toString() {
-        StringBuffer toString = new StringBuffer();
+        StringBuilder toString = new StringBuilder();
         toString.append("RetryMessage{");
         if (!StringUtils.isEmpty(messageDescription)) {
             toString.append("message:" + messageDescription + ", ");
         }
-        toString.append("size=" + bytes.length + ", ");
+        toString.append("size=" + ArrayUtils.getLength(bytes) + ", ");
         toString.append("retry=" + retryCount + "/" + maxRetryCount);
         toString.append("}");
 
