當(dāng)我使用個人阿里云測試機時，在查看實時輸出日志時，我發(fā)現(xiàn)數(shù)據(jù)庫連接失敗后，服務(wù)器一直在嘗試重新連接。一開始認(rèn)為系統(tǒng)遭受了連續(xù)的攻擊，但是在重新啟動服務(wù)后，就不再出現(xiàn)不斷重連的情況了?？匆韵螺敵鋈罩荆?/p>
2022-02-09 11:04:58.896 ERROR 16876 --- [eate-1550991149] com.alibaba.druid.pool.DruidDataSource ? : create connection SQLException, url: jdbc:mysql://47.98.67,98:1234/test?useSSL=false&characterEncoding=UTF-8&serverTimezone=UTC, errorCode 1045, state 28000java.sql.SQLException: Access denied for user 'root'@'113.90.123.76' (using password: YES)? ? at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129) ~[mysql-connector-java-8.0.16.jar:8.0.16]? ? at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) ~[mysql-connector-java-8.0.16.jar:8.0.16]? ? at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122) ~[mysql-connector-java-8.0.16.jar:8.0.16]? ? at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:835) ~[mysql-connector-java-8.0.16.jar:8.0.16]? ? at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java: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.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.alibaba.druid.filter.stat.StatFilter.connection_connect(StatFilter.java:218) ~[druid-1.1.10.jar:1.1.10]? ? at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:150) ~[druid-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.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:2468) ~[druid-1.1.10.jar:1.1.10]
注意上面一直有 druid 數(shù)據(jù)庫連接池的提示，這里就想到可能是 druid 連接池的問題，然后去掉 druid maven 依賴后在請求接口就不會出現(xiàn)重連的問題。
在上圖源碼找到最后一行 DruidDataSource.java:2468 定位到源碼上，CreateConnectionThread 創(chuàng)建連接線程，看一下 CreateConnectionThread 源碼：
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) {
// 必須存在線程等待，才創(chuàng)建連接
if (poolingCount >= notEmptyWaitThreadCount //
&& !(keepAlive && activeCount + poolingCount < minIdle)) {
empty.await();
}
// 防止創(chuàng)建超過maxActive數(shù)量的連接
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 方法里面設(shè)置了沒有限制的 for 循環(huán) for (;;) {}, 而日志報錯定位的信息:
connection = createPhysicalConnection();
如果符合條件 errorCount > connectionErrorRetryAttempts && timeBetweenConnectErrorMillis > 0 會再次嘗試重連，先看一下這幾個參數(shù)的含義：
在 run 方法初始化時為零，每次連接失敗，會自動加1
connectionErrorRetryAttempts
連接錯誤重試次數(shù)，默認(rèn)值為 1。
protected int connectionErrorRetryAttempts = 1;
timeBetweenConnectErrorMillis
連接間隔時間，單位毫秒。默認(rèn)值為 500。
protected volatile long timeBetweenConnectErrorMillis = DEFAULT_TIME_BETWEEN_CONNECT_ERROR_MILLIS; public static final long DEFAULT_TIME_BETWEEN_CONNECT_ERROR_MILLIS = 500;
我們在連接數(shù)據(jù)庫失敗后，要不在里面 break 中斷，其中有
if (breakAfterAcquireFailure) {
break;
}將改 break-after-acquire-failure 設(shè)置成 true,在 application.properties 文件如下配置：
spring.datasource.druid.break-after-acquire-failure=true
如果想多嘗試連接幾次，需要設(shè)置 connection-error-retry-attempts ,當(dāng) errorCount 大于 connectionErrorRetryAttempts 才會進(jìn)入到 條件內(nèi)，才會中斷循環(huán)。下面是 application.properties 文件的配置：
spring.datasource.druid.connection-error-retry-attempts=3
以上就是springboot?druid數(shù)據(jù)庫連接池連接失敗后一直重連怎么解決的詳細(xì)內(nèi)容，更多請關(guān)注php中文網(wǎng)其它相關(guān)文章！
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