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我们目前在我们的生产服务器上存在一个主要问题。我们在一台服务器上安装了MySQL DB（Ubuntu 14.04和MySQL 5.5.57版）。由于存在很多连接错误，MySQL主机被阻止
我们有另一台服务器，所有应用程序都与服务器上的数据库进行通话。连续5天，现在我们保持第二的服务器上获取此错误：
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)
我们一直在努力为5天，以解决这个问题，但我们每次重启MySQL的几个小时的时间，然后错误再次启动。我把max_connect_errors从10提高到了50，但这只是延长了错误。
然后我们也调整了日志级别为2，但我们在错误日志中唯一看到的是中止连接，没有'拒绝'连接。
有没有什么办法可以看到实际的连接错误？请帮忙解决这个问题，我不知道如何解决。我们也没有DBA，所以它只是一个不是数据库专家的开发团队。
编辑：该应用程序是一个Java Maven应用程序，使用休眠连接到数据库。这里是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>
我们总是在finally块紧密的联系：
} finally {
if (session != null) {
try {
session.close();
} catch (Exception e) {}
}
session = null;
}
我知道我们可以刷新主机或重启MySQL，但我不能这样做所有的时间都在生产服务器上。我想知道为什么我们会收到连接错误以及在哪里看到它们？
你是否关闭了你的连接？ –
您是否在多个线程之间共享您的Connection对象，这些对象不是线程安全的 – Ferrybig
另请参阅https://stackoverflow.com/questions/22285318/how-to-unblock-with-mysqladmin-flush-hosts –