--- a/src/main/java/christie/codegear/StartCodeGear.java	Thu Dec 14 20:46:18 2017 +0900
+++ b/src/main/java/christie/codegear/StartCodeGear.java	Wed Dec 27 00:06:50 2017 +0900
@@ -1,20 +1,22 @@
 package christie.codegear;
 
 import java.util.HashMap;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 
 public abstract class StartCodeGear implements Runnable {
-    static HashMap<String, CodeGearManager> cgms = new HashMap<String, CodeGearManager>();
-    static LinkedBlockingQueue<Runnable> taskQueue = new LinkedBlockingQueue<Runnable>();
-    static ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(Runtime.getRuntime().availableProcessors(), // initial number of threads
+    ConcurrentHashMap<String, CodeGearManager> cgms = new ConcurrentHashMap<>();
+    LinkedBlockingQueue<Runnable> taskQueue = new LinkedBlockingQueue<Runnable>();
+    ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(Runtime.getRuntime().availableProcessors(), // initial number of threads
             Runtime.getRuntime().availableProcessors(),
             Integer.MAX_VALUE, // keepAliveTime
             TimeUnit.SECONDS,
             taskQueue);
 
-    public static CodeGearManager createCGM(String name){
+
+    public CodeGearManager createCGM(String name){
         CodeGearManager cgm = new CodeGearManager(threadPoolExecutor);
         cgms.put(name, cgm);
         return cgm;