我们突然开始在声纳中遇到错误，不知道它可能是什么
Caused by: org.sonar.api.database.DatabaseException: Cannot open connection to database: Cannot create PoolableConnectionFactory (Communications link failure
Last packet sent to the server was 0 ms ago.)
at org.sonar.api.database.AbstractDatabaseConnector.testConnection(AbstractDatabaseConnector.java:182) [sonar-plugin-api-2.2.jar:na]
at org.sonar.api.database.AbstractDatabaseConnector.start(AbstractDatabaseConnector.java:94) [sonar-plugin-api-2.2.jar:na]
at org.sonar.server.database.JndiDatabaseConnector.start(JndiDatabaseConnector.java:65) [JndiDatabaseConnector.class:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [na:1.6.0_21]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) [na:1.6.0_21]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [na:1.6.0_21]
at java.lang.reflect.Method.invoke(Method.java:597) [na:1.6.0_21]
at org.picocontainer.lifecycle.ReflectionLifecycleStrategy.invokeMethod(ReflectionLifecycleStrategy.java:110) [picocontainer-2.10.2.jar:na]
... 35 common frames omitted
Caused by: org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (Communications link failure
Last packet sent to the server was 0 ms ago.)
at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1225) [commons-dbcp-1.2.2.jar:1.2.2]
at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:880) [commons-dbcp-1.2.2.jar:1.2.2]
at org.sonar.server.database.JndiDatabaseConnector.getConnection(JndiDatabaseConnector.java:154) [JndiDatabaseConnector.class:na]
at org.sonar.api.database.AbstractDatabaseConnector.testConnection(AbstractDatabaseConnector.java:178) [sonar-plugin-api-2.2.jar:na]
... 42 common frames omitted
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure