diff --git a/SqliteWAL/main.cc b/SqliteWAL/main.cc
index 303ad15..8a29d9d 100644
--- a/SqliteWAL/main.cc
+++ b/SqliteWAL/main.cc
@@ -1,12 +1,50 @@
 #include "sqlutils.hpp"
 
 #include <QCoreApplication>
+#include <QMutex>
+#include <QSqlDatabase>
+#include <QWaitCondition>
 
 #include <thread>
 
-void insertThread(const QString &brand)
+class CountDownLatch
+{
+    Q_DISABLE_COPY_MOVE(CountDownLatch)
+public:
+    explicit CountDownLatch(int count)
+        : m_count(count)
+    {}
+    void countDown()
+    {
+        QMutexLocker lock(&m_mutex);
+        if (--m_count == 0) {
+            m_condition.wakeAll();
+        }
+    }
+    int count() const
+    {
+        QMutexLocker lock(&m_mutex);
+        return m_count;
+    }
+
+    void wait()
+    {
+        QMutexLocker lock(&m_mutex);
+        while (m_count > 0) {
+            m_condition.wait(&m_mutex);
+        }
+    }
+
+private:
+    mutable QMutex m_mutex;
+    QWaitCondition m_condition;
+    int m_count;
+};
+
+void insertThread(const QString &brand, CountDownLatch &countDown)
 {
     SqlUtils sqlUtils;
+    countDown.wait();
     for (int i = 0; i < 500; i++) {
         sqlUtils.insert(brand, i);
     }
@@ -16,15 +54,22 @@ int main(int argc, char *argv[])
 {
     QCoreApplication a(argc, argv);
 
-    SqlUtils sqlUtils;
+    if (!QSqlDatabase::drivers().contains("QSQLITE")) {
+        qWarning() << "This demo needs the SQLITE driver";
+        return -1;
+    }
 
     const QStringList brands{"Apple", "Samsung", "Xiaomi", "Huawei", "Oppo", "Vivo", "Realme"};
+    CountDownLatch countDown(1);
     std::vector<std::thread> threads;
     for (const auto &brand : brands) {
-        threads.emplace_back(insertThread, brand);
+        threads.emplace_back(insertThread, brand, std::ref(countDown));
     }
+    countDown.countDown();
     for (auto &thread : threads) {
-        thread.join();
+        if (thread.joinable()) {
+            thread.join();
+        }
     }
 
     return 0;
diff --git a/SqliteWAL/sqlutils.cc b/SqliteWAL/sqlutils.cc
index 5b635d5..c407317 100644
--- a/SqliteWAL/sqlutils.cc
+++ b/SqliteWAL/sqlutils.cc
@@ -1,6 +1,5 @@
 #include "sqlutils.hpp"
 
-#include <QCoreApplication>
 #include <QDebug>
 #include <QSqlDatabase>
 #include <QSqlError>
@@ -12,24 +11,11 @@ class SqlUtils::SqlUtilsPrivate
     SqlUtilsPrivate(SqlUtils *q)
         : q_ptr(q)
     {
-        if (checkSQLITEDriver()) {
-            openSqliteDatabase();
-        }
+        openSqliteDatabase();
     }
 
     ~SqlUtilsPrivate() { QSqlDatabase::removeDatabase(connectionName); }
 
-    bool checkSQLITEDriver()
-    {
-        if (QSqlDatabase::drivers().contains("QSQLITE")) {
-            return true;
-        }
-
-        qWarning() << "This demo needs the SQLITE driver";
-        QMetaObject::invokeMethod(qApp, &QCoreApplication::quit, Qt::QueuedConnection);
-        return false;
-    }
-
     void openSqliteDatabase()
     {
         s_instanceCount.ref();