當我使用個人阿里雲測試機時，在查看即時輸出日誌時，我發現資料庫連線失敗後，伺服器一直在嘗試重新連線。一開始認為系統遭受了連續的攻擊，但是在重新啟動服務後，就不再出現不斷重連的情況了。看以下輸出日誌：
2022-02-09 11:04:58.896 ERROR 16876 --- [eate-1550991149] com.alibaba.druid.pool.DruidDataSource : create connection SQL. jdbc:mysql://47.98.67,98:1234/test?useSSL=false&characterEncoding=UTF-8&serverTimezone=UTC, errorCode 1045, state 28000
.sql.SQLExrootception: Access debt' @'113.90.123.76' (using password: YES)
注意上面一直有druid 資料庫連結池的提示，這裡就想到可能是druid 連結池的問題，然後去掉druid maven 依賴後在請求介面就不會出現重連的問題。
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129) ~[my-connector-javajar-8.0.1SQLError.java:129) ~[my-connector-javajar-8.116. 8.0.16]
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) ~[mysql-connector-java-8.0.16.jar:8.0.16] ~[mysql-connector-java-8.0.16.jar:8.0.16] ##o com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122) ~[mysql-connector-java-8.0.16.jar:8.0.16]
at com.mysql at com.mysql c.b. ConnectionImpl。 :455) ~[mysql-connector-java-8.0.16.jar:8.0.16]
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:240) ~[mysql-connector-java -8.0.16.jar:8.0.16]
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:199) ~[mysql-connector-java-8.0.16.jarr.java:199) ~[mysql-connector-java-8.0.16.jar:8.0.16 ]
at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:156) ~[druid-1.1.10.jar:1.1.10]
at com.b. .StatFilter.connection_connect(StatFilter.java:218) ~[druid-1.1.10.jar:1.1.10]
at com.alibaba.druid.filter.FilterChainImpl.connection_connect(alibaba.druid.filter.FilterChainImpl.connection_connect(alibaba.druid.filter.FilterChainImpl.connection_connect( -1.1.10.jar:1.1.10]
at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1560) ~[druid-1.1.10.jar:1.1.10]
at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1623) ~[druid-1.1.10.jar:1.1.10]
at com.alibabaConnection.jardruid.DruConnection. (DruidDataSource.java:2468) ~[druid-1.1.10.jar:1.1.10]
druid 重連原因
public class CreateConnectionThread extends Thread { public CreateConnectionThread(String name){ super(name); this.setDaemon(true); } public void run() { initedLatch.countDown(); long lastDiscardCount = 0; int errorCount = 0; for (;;) { // addLast try { lock.lockInterruptibly(); } catch (InterruptedException e2) { break; } long discardCount = DruidDataSource.this.discardCount; boolean discardChanged = discardCount - lastDiscardCount > 0; lastDiscardCount = discardCount; try { boolean emptyWait = true; if (createError != null && poolingCount == 0 && !discardChanged) { emptyWait = false; } if (emptyWait && asyncInit && createCount < initialSize) { emptyWait = false; } if (emptyWait) { // 必须存在线程等待，才创建连接 if (poolingCount >= notEmptyWaitThreadCount // && !(keepAlive && activeCount + poolingCount < minIdle)) { empty.await(); } // 防止创建超过maxActive数量的连接 if (activeCount + poolingCount >= maxActive) { empty.await(); continue; } } } catch (InterruptedException e) { lastCreateError = e; lastErrorTimeMillis = System.currentTimeMillis(); if (!closing) { LOG.error("create connection Thread Interrupted, url: " + jdbcUrl, e); } break; } finally { lock.unlock(); } PhysicalConnectionInfo connection = null; try { connection = createPhysicalConnection(); setFailContinuous(false); } catch (SQLException e) { LOG.error("create connection SQLException, url: " + jdbcUrl + ", errorCode " + e.getErrorCode() + ", state " + e.getSQLState(), e); errorCount++; if (errorCount > connectionErrorRetryAttempts && timeBetweenConnectErrorMillis > 0) { // fail over retry attempts setFailContinuous(true); if (failFast) { lock.lock(); try { notEmpty.signalAll(); } finally { lock.unlock(); } } if (breakAfterAcquireFailure) { break; } try { Thread.sleep(timeBetweenConnectErrorMillis); } catch (InterruptedException interruptEx) { break; } } } catch (RuntimeException e) { LOG.error("create connection RuntimeException", e); setFailContinuous(true); continue; } catch (Error e) { LOG.error("create connection Error", e); setFailContinuous(true); break; } if (connection == null) { continue; } boolean result = put(connection); if (!result) { JdbcUtils.close(connection.getPhysicalConnection()); LOG.info("put physical connection to pool failed."); } errorCount = 0; // reset errorCount } } }
這是一個多線程的類，而run 方法裡面設置了沒有限制的for 循環for (;;) {}, 而日誌報錯定位的信息:
connection = createPhysicalConnection();
如果符合條件errorCount > connectionErrorRetryAttempts && timeBetweenConnectErrorMillis > 0 會再嘗試重連，先看一下這幾個參數的意義：
errorCount 錯誤次數
連接錯誤重試次數，預設值為1。
protected int connectionErrorRetryAttempts = 1;
#連線間隔時間，單位毫秒。預設值為 500。
protected volatile long timeBetweenConnectErrorMillis = DEFAULT_TIME_BETWEEN_CONNECT_ERROR_MILLIS; public static final long DEFAULT_TIME_BETWEEN_CONNECT_ERROR_MILLIS = 500;
我們在連接資料庫失敗後，要不在裡面break 中斷，其中有
if (breakAfterAcquireFailure) { break; }
將改變break-after-acquire-failure 設定成true,在application.properties 檔案如下設定：
spring.datasource.druid.break-after-acquire-failure=true
如果想多嘗試連接幾次，需要設定connection-error-retry-attempts ,當errorCount 大於connectionErrorRetryAttempts 才會進入到條件內，才會中斷循環。下面是 application.properties 檔案的設定：
spring.datasource.druid.connection-error-retry-attempts=3
以上是springboot druid資料庫連線池連線失敗後一直重連怎麼解決的詳細內容。更多資訊請關注PHP中文網其他相關文章！
