try to solve defects found by coverity

apollo-client/src/main/java/com/ctrip/framework/apollo/ConfigService.java

@@ -21,8 +21,8 @@ public class ConfigService {
   private static final ConfigService s_instance = new ConfigService();
 
   private PlexusContainer m_container;
-  private ConfigManager m_configManager;
-  private ConfigRegistry m_configRegistry;
+  private volatile ConfigManager m_configManager;
+  private volatile ConfigRegistry m_configRegistry;
 
   private ConfigService() {
     m_container = ContainerLoader.getDefaultContainer();
@@ -128,8 +128,10 @@ public class ConfigService {
 
   // for test only
   static void setContainer(PlexusContainer m_container) {
-    s_instance.m_container = m_container;
-    s_instance.m_configManager = null;
-    s_instance.m_configRegistry = null;
+    synchronized (s_instance) {
+      s_instance.m_container = m_container;
+      s_instance.m_configManager = null;
+      s_instance.m_configRegistry = null;
+    }
   }
 }

apollo-core/src/main/java/com/ctrip/framework/apollo/tracer/Tracer.java

@@ -16,7 +16,7 @@ public abstract class Tracer {
   private static final Logger logger = LoggerFactory.getLogger(Tracer.class);
   private static final MessageProducerManager NULL_MESSAGE_PRODUCER_MANAGER =
       new NullMessageProducerManager();
-  private static MessageProducerManager producerManager;
+  private static volatile MessageProducerManager producerManager;
   private static Object lock = new Object();
 
   static {