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！
