Question

我正在使用C3P0和MS SQL JDBC 4驱动程序在数据库消失时自动故障转移到新的数据库镜像。如果它首先连接到主体数据库，则故障转移将起作用，并且无缝切换到镜像数据库。但是，如果主应用程序在应用程序启动时关闭，并且镜像数据库可用于连接（使用MSSQL Studio进行测试），则应用程序无法启动并无法连接到备份镜像。

这是连接网址：

jdbc:sqlserver://PRINCIPALDB;databaseName=app_space;port=99999;failoverPartner=MIRRORDB

我设置了c3p0.testConnectionOnCheckout和c3p0.preferredTestQuery，并且未设置c3p0.acquireRetryAttempts（默认设置为30）。

为什么当主体关闭时它不会最初连接到镜像DB？我们需要这个，因为如果电源关闭或者主要数据库出现问题，并且应用服务器需要回收，那么故障转移将无济于事。

参考：

http://www.mchange.com/projects/c3p0/#configuring_recovery

Using Database Mirroring (JDBC)（MSDN在其网址中使用未转义的括号！） http://msdn.microsoft.com/en-US/library/aa342332(v=sql.90)

以下是该应用的一些日志。

<14>[APP]: INFO 20 Jul 2012 12:21:21,982 [main] net.sf.hibernate.connection.C3P0ConnectionProvider "C3P0 using driver: com.microsoft.sqlserver.jdbc.SQLServerDriver at URL: jdbc:sqlserver://PRINCIPAL;databaseName=APP_space;port=9999;failoverPartner=MIRRORDB"    
<14>[APP]: INFO 20 Jul 2012 12:21:21,982 [main] net.sf.hibernate.connection.C3P0ConnectionProvider "Connection properties: {user=USERNAME, password=PASSWORD}"    
<14>[APP]: INFO 20 Jul 2012 12:21:22,435 [main] net.sf.hibernate.transaction.TransactionFactoryFactory "Transaction strategy: net.sf.hibernate.transaction.JDBCTransactionFactory"
<14>[APP]: INFO 20 Jul 2012 12:21:22,450 [main] net.sf.hibernate.transaction.TransactionManagerLookupFactory "No TransactionManagerLookup configured (in JTA environment, use of process level read-write cache is not recommended)"    
<12>[APP]: WARN 20 Jul 2012 12:29:17,279 [main] net.sf.hibernate.cfg.SettingsFactory "Could not obtain connection metadata"    
<12>java.sql.SQLException: Connections could not be acquired from the underlying database! 
<12>    at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106) 
<12>    at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:529) 
<12>    at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128) 
<12>    at net.sf.hibernate.connection.C3P0ConnectionProvider.getConnection(C3P0ConnectionProvider.java:33) 
<12>    at net.sf.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:84)

这是一种不同类型的错误，它有时会出现死锁警告。

<14>[APP]: INFO 20 Jul 2012 18:05:43,049 [main] net.sf.hibernate.connection.C3P0ConnectionProvider "C3P0 using driver: com.microsoft.sqlserver.jdbc.SQLServerDriver at URL: jdbc:sqlserver://PRINCIPALDB:9999;databaseName=APP_space;failoverPartner=MIRRORDB:9999"
<14>[APP]: INFO 20 Jul 2012 18:05:43,049 [main] net.sf.hibernate.connection.C3P0ConnectionProvider "Connection properties: {user=USERNAME, password=PASSWORD}"
<14>[APP]: INFO 20 Jul 2012 18:05:43,190 [main] com.mchange.v2.log.MLog "MLog clients using log4j logging."
<14>[APP]: INFO 20 Jul 2012 18:05:43,518 [main] com.mchange.v2.c3p0.C3P0Registry "Initializing c3p0-0.9.1.2 [built 21-May-2007 15:04:56; debug? true; trace: 10]"
<14>[APP]: INFO 20 Jul 2012 18:05:43,612 [main] net.sf.hibernate.transaction.TransactionFactoryFactory "Transaction strategy: net.sf.hibernate.transaction.JDBCTransactionFactory"
<14>[APP]: INFO 20 Jul 2012 18:05:43,612 [main] net.sf.hibernate.transaction.TransactionManagerLookupFactory "No TransactionManagerLookup configured (in JTA environment, use of process level read-write cache is not recommended)"
<14>[APP]: INFO 20 Jul 2012 18:05:43,658 [main] com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource "Initializing c3p0 pool... com.mchange.v2.c3p0.PoolBackedDataSource@616301db [ connectionPoolDataSource -> com.mchange.v2.c3p0.WrapperConnectionPoolDataSource@d6ed198b [ acquireIncrement -> 5, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, debugUnreturnedConnectionStackTraces -> false, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, identityToken -> 1bqq23w8o1a6dec41cwe1cd|20e1bfee, idleConnectionTestPeriod -> 100, initialPoolSize -> 10, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxI...
<14>...dleTime -> 3600, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 150, maxStatements -> 1000, maxStatementsPerConnection -> 0, minPoolSize -> 10, nestedDataSource -> com.mchange.v2.c3p0.DriverManagerDataSource@2c0fb781 [ description -> null, driverClass -> null, factoryClassLocation -> null, identityToken -> 1bqq23w8o1a6dec41cwe1cd|20360e46, jdbcUrl -> jdbc:sqlserver://PRINCIPALDB:9999;databaseName=APP_space;failoverPartner=MIRRORDB:9999, properties -> {user=******, password=******} ], preferredTestQuery -> select * from CLUSTERSAFETY, propertyCycle -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, usesTraditionalReflectiveProxies -> false; userOverrides: {} ], dataSourceName -> null, factoryClassLocation -> null, identityToken -> 1bqq23w8o1a6dec41cwe1cd|6f3e49a8, numHelperThreads -> 3 ]"
<12>[APP]: WARN 20 Jul 2012 18:06:03,644 [Timer-0] com.mchange.v2.async.ThreadPoolAsynchronousRunner "com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@37f844f7 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!"
<12>[APP]: WARN 20 Jul 2012 18:06:03,644 [Timer-0] com.mchange.v2.async.ThreadPoolAsynchronousRunner "com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@37f844f7 -- APPARENT DEADLOCK!!! Complete Status: 
    Managed Threads: 3
    Active Threads: 3
    Active Tasks: 
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@52783859 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0)
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@52bb855b (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1)
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@153043cc (com.mchange.v2.asyn...
<12>...c.ThreadPoolAsynchronousRunner$PoolThread-#2)
    Pending Tasks:

我使用此连接从文档中运行了一个测试程序：

jdbc:sqlserver://PRINCIPALDB:9999;databaseName=APP_space;portNumber=9999;failoverPartner=MIRRORDB:9999

并抛出此异常，就像它尝试的端口不同于我指定的端口！

Connection to principal server failed, trying the mirror server.
com.microsoft.sqlserver.jdbc.SQLServerException: The TCP/IP connection to the host MIRRORDB:9999, port 1433 has failed. Error: "null. Verify the connection properties. Make sure that an instance of SQL Server is running on the host and accepting TCP/IP connections at the port. Make sure that TCP connections to the port are not blocked by a firewall.".
    at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(SQLServerException.java:190)

重要的是，它尝试连接到端口1433而不是我指定的端口，有许多不同的方式。

Answer 1

我找到了答案！您必须将实例名称指定为主机名的一部分！例如：

jdbc:sqlserver://DEVSQLB\SQLB;databaseName=db_space;portNumber=99999;failoverPartner=BACKUPSQLA\SQLA

其中\SQLA是实例名称！我不确定实例是什么，但我在SQL Server中已经多次看到它。为了找到这个秘密信息，我（我的公司）必须直接向Microsoft请求支持。

哦，忘了：

您可以使用格式“server \ instance_name”解决此问题并确保浏览器服务正在运行且处于自动模式。

Answer 2

Sql Server JDBC驱动程序文档here具有以下（令人困惑的）免责声明：

注意驱动程序不支持将故障转移伙伴实例的服务器实例端口号指定为连接字符串中failoverPartner属性的一部分。但是，支持在同一连接字符串中指定主体服务器实例的serverName，instanceName和portNumber属性以及故障转移伙伴实例的failoverPartner属性。

由此我建议添加：的 SERVERNAME = PRINCIPALDB;实例名= MYINSTANCE 属性，看看是否有效。

您提到故障转移处于活动状态。请注意，对于某些Sql Server镜像配置，故障转移不是automatic。您可能需要验证是否可以使用jdbc连接到 MIRRORDB ：

jdbc:sqlserver://MIRRORDB;databaseName=app_space;port=9999;

MSSQL JDBC驱动程序在第一次连接时不会连接到镜像failoverPartner

2 个答案: