diff --git a/src/main/java/com/actiontech/dble/config/helper/GetAndSyncDbInstanceKeyVariables.java b/src/main/java/com/actiontech/dble/config/helper/GetAndSyncDbInstanceKeyVariables.java
index 3ee799402f..3f35ded146 100644
--- a/src/main/java/com/actiontech/dble/config/helper/GetAndSyncDbInstanceKeyVariables.java
+++ b/src/main/java/com/actiontech/dble/config/helper/GetAndSyncDbInstanceKeyVariables.java
@@ -69,9 +69,11 @@ public KeyVariables call() {
             while (!isFinish) {
                 boolean await = finishCond.await(ds.getConfig().getPoolConfig().getHeartbeatPeriodMillis(), TimeUnit.MILLISECONDS);
                 if (!await) {
-                    fail = true;
-                    isFinish = true;
-                    LOGGER.warn("test conn timeout,TCP connection may be lost");
+                    if (!isFinish) {
+                        fail = true;
+                        isFinish = true;
+                        LOGGER.warn("test conn timeout,TCP connection may be lost");
+                    }
                 }
             }
         } catch (InterruptedException e) {
@@ -86,89 +88,85 @@ public KeyVariables call() {
     private class GetDbInstanceKeyVariablesListener implements SQLQueryResultListener<SQLQueryResult<Map<String, String>>> {
         @Override
         public void onResult(SQLQueryResult<Map<String, String>> result) {
-            if (result.isSuccess()) {
-                ds.setTestConnSuccess(true);
-                keyVariables = new KeyVariables();
-                keyVariables.setLowerCase(!result.getResult().get(COLUMN_LOWER_CASE).equals("0"));
-
-                keyVariables.setAutocommit(result.getResult().get(COLUMN_AUTOCOMMIT).equals("1"));
-                keyVariables.setTargetAutocommit(SystemConfig.getInstance().getAutocommit() == 1);
-
-                String isolation = result.getResult().get(columnIsolation);
-                switch (isolation) {
-                    case "READ-COMMITTED":
-                        keyVariables.setIsolation(Isolations.READ_COMMITTED);
-                        break;
-                    case "READ-UNCOMMITTED":
-                        keyVariables.setIsolation(Isolations.READ_UNCOMMITTED);
-                        break;
-                    case "REPEATABLE-READ":
-                        keyVariables.setIsolation(Isolations.REPEATABLE_READ);
-                        break;
-                    case "SERIALIZABLE":
-                        keyVariables.setIsolation(Isolations.SERIALIZABLE);
-                        break;
-                    default:
-                        break;
+            boolean isSuccess = result.isSuccess();
+            ds.setTestConnSuccess(isSuccess);
+            lock.lock();
+            try {
+                if (isFinish) {
+                    if (fail)
+                        LOGGER.info("test conn timeout, need to resynchronize");
+                    return;
                 }
-                keyVariables.setTargetIsolation(SystemConfig.getInstance().getTxIsolation());
-                keyVariables.setMaxPacketSize(Integer.parseInt(result.getResult().get(COLUMN_MAX_PACKET)));
-                keyVariables.setTargetMaxPacketSize(SystemConfig.getInstance().getMaxPacketSize() + KeyVariables.MARGIN_PACKET_SIZE);
-                keyVariables.setReadOnly(result.getResult().get(COLUMN_READONLY).equals("1"));
-                keyVariables.setVersion(result.getResult().get(COLUMN_VERSION));
-                keyVariables.setBackLog(Integer.parseInt(result.getResult().get(COLUMN_BACK_LOG)));
+                if (isSuccess) {
+                    ds.setTestConnSuccess(true);
+                    keyVariables = new KeyVariables();
+                    keyVariables.setLowerCase(!result.getResult().get(COLUMN_LOWER_CASE).equals("0"));
 
-                if (needSync) {
-                    boolean checkNeedSync = false;
-                    if (keyVariables.getTargetMaxPacketSize() > keyVariables.getMaxPacketSize()) {
-                        checkNeedSync = true;
-                    }
-                    if (keyVariables.isTargetAutocommit() != keyVariables.isAutocommit()) {
-                        checkNeedSync = true;
-                    } else {
-                        ds.setAutocommitSynced(true);
-                    }
-                    if (keyVariables.getTargetIsolation() != keyVariables.getIsolation()) {
-                        checkNeedSync = true;
-                    } else {
-                        ds.setIsolationSynced(true);
+                    keyVariables.setAutocommit(result.getResult().get(COLUMN_AUTOCOMMIT).equals("1"));
+                    keyVariables.setTargetAutocommit(SystemConfig.getInstance().getAutocommit() == 1);
+
+                    String isolation = result.getResult().get(columnIsolation);
+                    switch (isolation) {
+                        case "READ-COMMITTED":
+                            keyVariables.setIsolation(Isolations.READ_COMMITTED);
+                            break;
+                        case "READ-UNCOMMITTED":
+                            keyVariables.setIsolation(Isolations.READ_UNCOMMITTED);
+                            break;
+                        case "REPEATABLE-READ":
+                            keyVariables.setIsolation(Isolations.REPEATABLE_READ);
+                            break;
+                        case "SERIALIZABLE":
+                            keyVariables.setIsolation(Isolations.SERIALIZABLE);
+                            break;
+                        default:
+                            break;
                     }
+                    keyVariables.setTargetIsolation(SystemConfig.getInstance().getTxIsolation());
+                    keyVariables.setMaxPacketSize(Integer.parseInt(result.getResult().get(COLUMN_MAX_PACKET)));
+                    keyVariables.setTargetMaxPacketSize(SystemConfig.getInstance().getMaxPacketSize() + KeyVariables.MARGIN_PACKET_SIZE);
+                    keyVariables.setReadOnly(result.getResult().get(COLUMN_READONLY).equals("1"));
+                    keyVariables.setVersion(result.getResult().get(COLUMN_VERSION));
+                    keyVariables.setBackLog(Integer.parseInt(result.getResult().get(COLUMN_BACK_LOG)));
 
-                    if (checkNeedSync) {
-                        SyncDbInstanceKeyVariables task = new SyncDbInstanceKeyVariables(keyVariables, ds);
-                        boolean synced = false;
-                        try {
-                            synced = task.call();
-                        } catch (Exception e) {
-                            LOGGER.warn("SyncDbInstanceKeyVariables error", e);
+                    if (needSync) {
+                        boolean checkNeedSync = false;
+                        if (keyVariables.getTargetMaxPacketSize() > keyVariables.getMaxPacketSize()) {
+                            checkNeedSync = true;
                         }
-                        if (synced) {
+                        if (keyVariables.isTargetAutocommit() != keyVariables.isAutocommit()) {
+                            checkNeedSync = true;
+                        } else {
                             ds.setAutocommitSynced(true);
+                        }
+                        if (keyVariables.getTargetIsolation() != keyVariables.getIsolation()) {
+                            checkNeedSync = true;
+                        } else {
                             ds.setIsolationSynced(true);
-                            keyVariables.setMaxPacketSize(keyVariables.getTargetMaxPacketSize());
                         }
-                    }
-                }
-            } else {
-                ds.setTestConnSuccess(false);
-            }
 
-            handleFinished();
-        }
+                        if (checkNeedSync) {
+                            SyncDbInstanceKeyVariables task = new SyncDbInstanceKeyVariables(keyVariables, ds);
+                            boolean synced = false;
+                            try {
+                                synced = task.call();
+                            } catch (Exception e) {
+                                LOGGER.warn("SyncDbInstanceKeyVariables error", e);
+                            }
 
-        private void handleFinished() {
-            lock.lock();
-            try {
+                            if (synced) {
+                                ds.setAutocommitSynced(true);
+                                ds.setIsolationSynced(true);
+                                keyVariables.setMaxPacketSize(keyVariables.getTargetMaxPacketSize());
+                            }
+                        }
+                    }
+                }
                 isFinish = true;
                 finishCond.signal();
-                if (fail) {
-                    keyVariables = null;
-                    LOGGER.info("test conn timeout, need to resynchronize");
-                }
             } finally {
                 lock.unlock();
             }
         }
     }
-
 }