add sharding visitor

src/test/java/com/alibaba/druid/bvt/pool/TestActiveTrace.java

@@ -0,0 +1,50 @@
+package com.alibaba.druid.bvt.pool;
+
+import java.lang.management.ManagementFactory;
+import java.sql.Connection;
+
+import junit.framework.Assert;
+import junit.framework.TestCase;
+
+import com.alibaba.druid.pool.DruidDataSource;
+import com.alibaba.druid.stat.DruidDataSourceStatManager;
+
+public class TestActiveTrace extends TestCase {
+
+    private DruidDataSource dataSource;
+
+    protected void setUp() throws Exception {
+        Assert.assertEquals(0, DruidDataSourceStatManager.getInstance().getDataSourceList().size());
+
+        dataSource = new DruidDataSource();
+        dataSource.setRemoveAbandoned(true);
+        dataSource.setRemoveAbandonedTimeoutMillis(10);
+        dataSource.setLogAbandoned(true);
+        dataSource.setTimeBetweenEvictionRunsMillis(10);
+        dataSource.setMinEvictableIdleTimeMillis(300 * 1000);
+        dataSource.setUrl("jdbc:mock:xxx");
+
+    }
+
+    protected void tearDown() throws Exception {
+        dataSource.close();
+        Assert.assertEquals(0, DruidDataSourceStatManager.getInstance().getDataSourceList().size());
+    }
+
+    public void test_activeTrace() throws Exception {
+        for (int i = 0; i < 1000 * 1000; ++i) {
+            dataSource.shrink();
+
+            Connection conn = dataSource.getConnection();
+            conn.close();
+            // Assert.assertEquals(1, dataSource.getPoolingCount());
+            dataSource.shrink();
+            Assert.assertEquals(0, dataSource.getPoolingCount());
+            Assert.assertEquals(0, dataSource.getActiveConnections().size());
+
+            if (i % 5000 == 0) {
+                System.out.println(ManagementFactory.getClassLoadingMXBean().getLoadedClassCount());
+            }
+        }
+    }
+}