diff --git a/src/test/java/top/guoziyang/mydb/backend/dm/DataManagerTest.java b/src/test/java/top/guoziyang/mydb/backend/dm/DataManagerTest.java
index 141a94f..6de46ae 100644
--- a/src/test/java/top/guoziyang/mydb/backend/dm/DataManagerTest.java
+++ b/src/test/java/top/guoziyang/mydb/backend/dm/DataManagerTest.java
@@ -56,14 +56,19 @@ private void worker(DataManager dm0, DataManager dm1, int tasksNum, int insertRa
                     uids1.add(u1);
                     uidsLock.unlock();
                 } else {
+                    long u0, u1;
                     uidsLock.lock();
-                    if(uids0.size() == 0) {
+                    try {
+                        if (uids0.size() == 0) {
+                            continue;
+                        }
+                        int tmp = Math.abs(random.nextInt()) % uids0.size();
+                        u0 = uids0.get(tmp);
+                        u1 = uids1.get(tmp);
+                    } finally {
                         uidsLock.unlock();
-                        continue;
                     }
-                    int tmp = Math.abs(random.nextInt()) % uids0.size();
-                    long u0 = uids0.get(tmp);
-                    long u1 = uids1.get(tmp);
+                    
                     DataItem data0 = null, data1 = null;
                     try {
                         data0 = dm0.read(u0);
@@ -124,6 +129,8 @@ public void testDMMulti() throws InterruptedException {
         for(int i = 0; i < 10; i ++) {
             Runnable r = () -> worker(dm0, mdm, tasksNum, 50, cdl);
             new Thread(r).run();
+            // 真正的多线程
+            // new Thread(r).start();
         }
         cdl.await();
         dm0.close(); mdm.close();