BI-29723 druid连接池生产连接线程阻塞

fine-druid/src/com/fr/third/alibaba/druid/pool/DruidDataSource.java

@@ -139,6 +139,7 @@ public class DruidDataSource extends DruidAbstractDataSource implements DruidDat
     private DestroyTask destroyTask;
 
     private CreateConnectionThread createConnectionThread;
+    private PeriodDetectionThread periodDetectionThread;
     private DestroyConnectionThread destroyConnectionThread;
     private LogStatsThread logStatsThread;
     private int createTaskCount;
@@ -613,10 +614,10 @@ public class DruidDataSource extends DruidAbstractDataSource implements DruidDat
     }
 
     private void checkThread() throws SQLException {
-        if (createConnectionThread == null){
+        if (createConnectionThread == null) {
             throw new IllegalStateException("createConnectionThread not start!");
         }
-        if (destroyConnectionThread == null){
+        if (destroyConnectionThread == null) {
             throw new IllegalStateException("destroyConnectionThread not start!");
         }
         if (!createConnectionThread.isStarted() && !destroyConnectionThread.isStarted()) {
@@ -780,7 +781,7 @@ public class DruidDataSource extends DruidAbstractDataSource implements DruidDat
             createAndLogThread();
             createAndStartCreatorThread();
             createAndStartDestroyThread();
-
+            createAndStartDetectThread();
             initedLatch.await();
             init = true;
 
@@ -859,6 +860,14 @@ public class DruidDataSource extends DruidAbstractDataSource implements DruidDat
 
         initedLatch.countDown();
     }
+    private void createAndStartDetectThread() {
+        if(createScheduler == null){
+            String threadName = "Druid-ConnectionPool-Detection-" + System.identityHashCode(this) + this.getUrl();
+            periodDetectionThread = new PeriodDetectionThread(threadName);
+            periodDetectionThread.start();
+        }
+    }
+
 
     /**
      * load filters from SPI ServiceLoader
@@ -1526,7 +1535,9 @@ public class DruidDataSource extends DruidAbstractDataSource implements DruidDat
             if (destroyConnectionThread != null) {
                 destroyConnectionThread.interrupt();
             }
-
+            if (periodDetectionThread != null){
+                periodDetectionThread.interrupt();
+            }
             if (destroySchedulerFuture != null) {
                 destroySchedulerFuture.cancel(true);
             }
@@ -2198,6 +2209,33 @@ public class DruidDataSource extends DruidAbstractDataSource implements DruidDat
             this.started = started;
         }
     }
+    //周期性检查生产线程状态,因为在终止生产线程的时候，为了不让生产线程疯狂重试数据库，只是生成了一个生产线程，但是并没有start,需要一个守护线程
+    //周期性检查线程状态，帮助其启动。
+    private class PeriodDetectionThread extends Thread {
+        public PeriodDetectionThread(String name) {
+            super(name);
+            this.setDaemon(true);
+        }
+
+        public void run() {
+            while(true) {
+                synchronized (DruidDataSource.this) {
+                    //生产线程发生了切换，并且有线程在等待连接，需要主动唤醒生产线程，否则由
+                    if (!createConnectionThread.started && !destroyConnectionThread.started && notEmptyWaitThreadCount > 0) {
+                        createConnectionThread.setStarted(true);
+                        createConnectionThread.start();
+                        destroyConnectionThread.setStarted(true);
+                        destroyConnectionThread.start();
+                    }
+                }
+                try {
+                    Thread.sleep(timeBetweenConnectErrorMillis);
+                } catch (InterruptedException ignore) {
+                    break;
+                }
+            }
+        }
+    }
 
     public class DestroyConnectionThread extends Thread {
         private volatile boolean started = true;