2019独角兽企业重金招聘Python工程师标准>>> 
错误：
WARN com.mchange.v2.async.ThreadPoolAsynchronousRunner com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@27e467f7 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!
2015-04-30 10:29:43 WARN com.mchange.v2.async.ThreadPoolAsynchronousRunner com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@27e467f7 -- APPARENT DEADLOCK!!! Complete Status:
Managed Threads: 3
Active Threads: 3
Active Tasks:
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@6bd962a4 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2)
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@cdb344d (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0)
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@b46b1d3 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1)
Pending Tasks:
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@4e44996d
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@79b4eb3f
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@54c0b385
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@374a0c3b
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@5e6911d8
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@4412ac54
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@25efe1b6
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@27cb872f
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@23183312
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@9c0f4be
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@5b03eaf2
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@5e35e48c
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@242fd3a6
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@3ff049d9
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@3880665a
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@75bfbbb0
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@7ebb5c34
Pool thread stack traces:
Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2,5,main]
java.net.PlainSocketImpl.socketConnect(Native Method)
java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
java.net.Socket.connect(Socket.java:579)
java.net.Socket.connect(Socket.java:528)
java.net.Socket.<init>(Socket.java:425)
java.net.Socket.<init>(Socket.java:241)
com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:256)
com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:293)
com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2181)
com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:787)
com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:49)
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
java.lang.reflect.Constructor.newInstance(Constructor.java:526)
com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:357)
com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:285)
com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:135)
com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182)
com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:171)
com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137)
com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014)
com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0,5,main]
java.net.PlainSocketImpl.socketConnect(Native Method)
java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
java.net.Socket.connect(Socket.java:579)
java.net.Socket.connect(Socket.java:528)
java.net.Socket.<init>(Socket.java:425)
java.net.Socket.<init>(Socket.java:241)
com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:256)
com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:293)
com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2181)
com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:787)
com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:49)
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
java.lang.reflect.Constructor.newInstance(Constructor.java:526)
com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:357)
com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:285)
com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:135)
com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182)
com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:171)
com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137)
com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014)
com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1,5,main]
java.net.PlainSocketImpl.socketConnect(Native Method)
java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
java.net.Socket.connect(Socket.java:579)
java.net.Socket.connect(Socket.java:528)
java.net.Socket.<init>(Socket.java:425)
java.net.Socket.<init>(Socket.java:241)
com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:256)
com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:293)
com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2181)
com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:787)
com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:49)
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
java.lang.reflect.Constructor.newInstance(Constructor.java:526)
com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:357)
com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:285)
com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:135)
com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182)
com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:171)
com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137)
com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014)
com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)解决方法：
先关闭mysql数据库，然后在打开数据库，只限于测试环境，如果是正式环境请设置连接池的最大数量小于mysql的最大连接数量，而且不用mysql工具连接服务器，或者连接后及时关闭，减少连接数。