close MemMonitor in EnvironmentUtil.cleanEnv() (#164)

.travis.yml

@@ -70,6 +70,13 @@ matrix:
         - java -version
         - mvn -version
         - mvn -B clean integration-test
+      cache:
+        directories:
+          - '$HOME/.m2/repository'
+          - '$HOME/.sonar/cache'
+          - '/c/java11'
+          - '/c/mvn361'
+          
     - os: windows
       language: c
       name: win-oraclejdk8
@@ -88,6 +95,7 @@ matrix:
         - java -version
         - mvn -version
         - mvn -B clean integration-test
+
     - os: linux
       name: linux-openjdk11
       dist: trusty

iotdb/src/test/java/org/apache/iotdb/db/utils/EnvironmentUtils.java

@@ -95,11 +95,6 @@ public class EnvironmentUtils {
     // FileNodeManager.getInstance().reset();
     // reset MemController
     BasicMemController.getInstance().close();
-    try {
-      BasicMemController.getInstance().start();
-    } catch (StartupException e) {
-      LOGGER.error("", e);
-    }
   }
 
   private static void cleanAllDir() throws IOException {
@@ -175,5 +170,10 @@ public class EnvironmentUtils {
     MultiFileLogNodeManager.getInstance().start();
     TEST_QUERY_JOB_ID = QueryResourceManager.getInstance().assignJobId();
     TEST_QUERY_CONTEXT = new QueryContext(TEST_QUERY_JOB_ID);
+    try {
+      BasicMemController.getInstance().start();
+    } catch (StartupException e) {
+      LOGGER.error("", e);
+    }
   }
 }