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我們目前在我們的生產服務器上存在一個主要問題。我們在一臺服務器上安裝了MySQL DB（Ubuntu 14.04和MySQL 5.5.57版）。由於存在很多連接錯誤，MySQL主機被阻止
我們有另一臺服務器，所有應用程序都與服務器上的數據庫進行通話。連續5天，現在我們保持第二的服務器上獲取此錯誤：
05-09-2017 00:00:01 WARN com[email protected]623841b8 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception:
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
at sun.reflect.GeneratedConstructorAccessor32.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.Util.getInstance(Util.java:386)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1015)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:989)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:975)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:920)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2395)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2316)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:834)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.GeneratedConstructorAccessor19.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:416)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:347)
at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:146)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:195)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:184)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:200)
at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1086)
at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1073)
at com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:44)
at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1810)
at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:648)
Caused by: java.sql.SQLException: null, message from server: "Host 'IP_ADDRESS' is blocked because of many connection errors; unblock with 'mysqladmin flush-hosts'"
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1078)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:989)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:975)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1114)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2493)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2334)
我們一直在努力爲5天，以解決這個問題，但我們每次重啓MySQL的幾個小時的時間，然後錯誤再次啓動。我把max_connect_errors從10提高到了50，但這只是延長了錯誤。
然後我們也調整了日誌級別爲2，但我們在錯誤日誌中唯一看到的是中止連接，沒有'拒絕'連接。
有沒有什麼辦法可以看到實際的連接錯誤？請幫忙解決這個問題，我不知道如何解決。我們也沒有DBA，所以它只是一個不是數據庫專家的開發團隊。
編輯：該應用程序是一個Java Maven應用程序，使用休眠連接到數據庫。這裏是hibernate的配置文件：
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.username">USERNAME_HERE</property>
<property name="hibernate.connection.password">PASSWORD_HERE</property>
<property name="hibernate.connection.url">jdbc:mysql://SERVER_HERE:3306/voda_soccer?zeroDateTimeBehavior=convertToNull</property>
<property name="hibernate.connection.autoReconnect">true</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLInnoDBDialect</property>
<property name="hibernate.temp.use_jdbc_metadata_defaults">false</property>
<property name="show_sql">false</property>
<property name="hibernate.c3p0.min_size">5</property>
<property name="hibernate.c3p0.max_size">20</property>
<property name="hibernate.c3p0.timeout">300</property>
<property name="hibernate.c3p0.max_statements">50</property>
<property name="hibernate.c3p0.idle_test_period">3000</property>
<mapping class="com.myapp.sms.producer.entity.Customer"></mapping>
<mapping class="com.myapp.sms.producer.entity.Gifting"></mapping>
<mapping class="com.myapp.sms.producer.entity.BulkCampaign"></mapping>
</session-factory>
我們總是在finally塊緊密的聯繫：
} finally {
if (session != null) {
try {
session.close();
} catch (Exception e) {}
}
session = null;
}
我知道我們可以刷新主機或重啓MySQL，但我不能這樣做所有的時間都在生產服務器上。我想知道爲什麼我們會收到連接錯誤以及在哪裏看到它們？
你是否關閉了你的連接？ –
您是否在多個線程之間共享您的Connection對象，這些對象不是線程安全的 – Ferrybig
另請參閱https://stackoverflow.com/questions/22285318/how-to-unblock-with-mysqladmin-flush-hosts –