I'm trying to get some code I was passed up and running. It appears to use the Hibernate framework. I've gotten past most of the errors tweaking the configuration, but this one has me dead stumped.
It's trying to connect to two databases: gameapp and gamelog. Both exist. It seems to have issues connecting to gamelog, but none connecting to gameapp (later in the init, it connects to and loads other DBs just fine). Below, I've pasted the error and exception stack dump.
I imaging there's something else in the configs, so I've also included the configuration file for that db. I know this is very vague, but I'm hoping some pro can see the stupid mistake I'm missing.
<?xml version="1.0" encoding="GBK"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://127.0.0.1:3306/gamelog</property>
<property name="connection.username">root</property>
<property name="connection.password"></property>
<property name="connection.useUnicode">true</property>
<property name="connection.characterEncoding">UTF-8</property>
<property name="hibernate.jdbc.batch_size">100</property>
<property name="jdbc.fetch_size">1</property>
<property name="hbm2ddl.auto">none</property><!-- update -->
<property name="connection.useUnicode">true</property>
<property name="show_sql">true</property>
<!-- c3p0-configuration -->
<property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
<property name="hibernate.c3p0.min_size">5</property>
<property name="hibernate.c3p0.max_size">10</property>
<property name="hibernate.c3p0.timeout">30</property>
<property name="hibernate.c3p0.idle_test_period">30</property>
<property name="hibernate.c3p0.max_statements">0</property>
<property name="hibernate.c3p0.acquire_increment">5</property>
</session-factory>
</hibernate-configuration>
Exception and stack trace:
2010-04-30 17:50:00,411 WARN [org.hibernate.cfg.SettingsFactory] - Could not obtain connection metadata
java.sql.SQLException: An attempt by a client to checkout a Connection has timed out.
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:65)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:527)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
at org.hibernate.connection.C3P0ConnectionProvider.getConnection(C3P0ConnectionProvider.java:35)
at org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:76)
at org.hibernate.cfg.Configuration.buildSettings(Configuration.java:1933)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1216)
at com.database.hibernate.util.HibernateFactory.<init>(Unknown Source)
at com.database.hibernate.util.HibernateUtil.<clinit>(Unknown Source)
at com.server.databaseop.goodOp.GoodOpImpl.initBreedGoods(Unknown Source)
at com.server.databaseop.goodOp.GoodOpImpl.access$000(Unknown Source)
at com.server.databaseop.goodOp.GoodOpImpl$1.run(Unknown Source)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:351)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:178)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:165)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:267)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:636)
Caused by: com.mchange.v2.resourcepool.TimeoutException: A client timed out while waiting to acquire a resource from com.mchange.v2.resourcepool.BasicResourcePool@ca470 -- timeout at awaitAvailable()
at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1317)
at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557)
at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525)
... 18 more
If you have set C3P0's "checkoutTimeout" property to something other than 0 you might be timing out too quickly (that was my problem, solution: bumped it to 2000 milliseconds from 500).
Alternatively, there's a workaround for this warning:
Set the hibernate.temp.use_jdbc_metadata_defaults property to false.
Found this in http://www.docjar.com/html/api/org/hibernate/cfg/SettingsFactory.java.html, though there may be side effects of not having Hibernate extract JDBC Metadata defaults.
Actually that's not even an authentication error. Is MySQL even running or bound to localhost?
does telnet 127.0.0.1 3306 work? if so, install the mysql client on the box and try
mysql --user=root --ip=127.0.0.1 and see what happens
Check if you can connect to the gamelog mysql database on the command line with the root user and no password (!). As a side note, I'd recommend to set a password for root and to use a different account to connect to the database from your application, but that's another story.
来源：https://stackoverflow.com/questions/2746623/java-hibernate-c3p0-error-could-not-obtain-connection-metadata-an-attempt-by