2017-08-03 18:28:48.022  WARN 6396 --- [o-8080-exec-170] o.a.tomcat.jdbc.pool.ConnectionPool      : Connection has been abandoned PooledConnection[com.mysql.jdbc.JDBC4Connection@af6bbd]:java.lang.Exception
	at org.apache.tomcat.jdbc.pool.ConnectionPool.getThreadDump(ConnectionPool.java:1065)
	at org.apache.tomcat.jdbc.pool.ConnectionPool.createConnection(ConnectionPool.java:707)
	at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:634)
	at org.apache.tomcat.jdbc.pool.ConnectionPool.init(ConnectionPool.java:488)
	at org.apache.tomcat.jdbc.pool.ConnectionPool.<init>(ConnectionPool.java:144)
	at org.apache.tomcat.jdbc.pool.DataSourceProxy.pCreatePool(DataSourceProxy.java:116)
	at org.apache.tomcat.jdbc.pool.DataSourceProxy.createPool(DataSourceProxy.java:103)
	at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:127)
	......
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:521)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1096)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:674)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:745)

2017-08-03 18:28:48 ERROR [com.xxx.yyy.a.b] -- <Too many connections>
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Too many connections
	at sun.reflect.GeneratedConstructorAccessor295.newInstance(Unknown Source)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
	at com.mysql.jdbc.Util.getInstance(Util.java:384)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1015)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3562)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3494)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:920)
	at com.mysql.jdbc.MysqlIO.secureAuth411(MysqlIO.java:4000)
	at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1285)
	at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2186)
	at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:787)
	at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:49)
	at sun.reflect.GeneratedConstructorAccessor288.newInstance(Unknown Source)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
	at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:357)
	at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:285)
	at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:278)
	at org.apache.tomcat.jdbc.pool.PooledConnection.connect(PooledConnection.java:182)
	at org.apache.tomcat.jdbc.pool.ConnectionPool.createConnection(ConnectionPool.java:702)
	at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:634)
	at org.apache.tomcat.jdbc.pool.ConnectionPool.init(ConnectionPool.java:488)
	at org.apache.tomcat.jdbc.pool.ConnectionPool.<init>(ConnectionPool.java:144)
	at org.apache.tomcat.jdbc.pool.DataSourceProxy.pCreatePool(DataSourceProxy.java:116)
	at org.apache.tomcat.jdbc.pool.DataSourceProxy.createPool(DataSourceProxy.java:103)
	at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:127)
	......
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:521)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1096)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:674)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:745)