mq日志文件报错如下：
2020-08-10 22:53:10,549 | ERROR | HikariPool-1 - Exception during pool initialization. | com.zaxxer.hikari.pool.HikariPool | main
com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174)[mysql-connector-java-8.0.18.jar:8.0.18]
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64)[mysql-connector-java-8.0.18.jar:8.0.18]
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836)[mysql-connector-java-8.0.18.jar:8.0.18]
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456)[mysql-connector-java-8.0.18.jar:8.0.18]
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246)[mysql-connector-java-8.0.18.jar:8.0.18]
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:199)[mysql-connector-java-8.0.18.jar:8.0.18]
at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:136)[HikariCP-3.2.0.jar:]
at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:369)[HikariCP-3.2.0.jar:]
at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:198)[HikariCP-3.2.0.jar:]
at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:467)[HikariCP-3.2.0.jar:]
at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:541)[HikariCP-3.2.0.jar:]
at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115)[HikariCP-3.2.0.jar:]
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112)[HikariCP-3.2.0.jar:]
at org.apache.activemq.store.jdbc.TransactionContext.lockAndWrapped(TransactionContext.java:70)[activemq-jdbc-store-5.15.11.jar:5.15.11]
at org.apache.activemq.store.jdbc.TransactionContext.getConnection(TransactionContext.java:63)[activemq-jdbc-store-5.15.11.jar:5.15.11]
at org.apache.activemq.store.jdbc.JDBCPersistenceAdapter.loadAdapter(JDBCPersistenceAdapter.java:454)[activemq-jdbc-store-5.15.11.jar:5.15.11]
at org.apache.activemq.store.jdbc.JDBCPersistenceAdapter.createAdapter(JDBCPersistenceAdapter.java:437)[activemq-jdbc-store-5.15.11.jar:5.15.11]
at org.apache.activemq.store.jdbc.JDBCPersistenceAdapter.getAdapter(JDBCPersistenceAdapter.java:386)[activemq-jdbc-store-5.15.11.jar:5.15.11]
at org.apache.activemq.store.jdbc.JDBCPersistenceAdapter.init(JDBCPersistenceAdapter.java:299)[activemq-jdbc-store-5.15.11.jar:5.15.11]
at org.apache.activemq.broker.LockableServiceSupport.preStart(LockableServiceSupport.java:89)[activemq-broker-5.15.11.jar:5.15.11]
原因：
本地的mysql没有启动,启动mysql:
service mysql start
mysql启动后再启动activeMQ即可启动。
如果遇到本地的mysql无法启动：
当时我启动mysql时的问题：mysql.sock文件不存在。
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/usr/local/mysql/var/mysql.sock' (111)
解决方法：
到mysql的bin目录下：执行
./mysql restart
发现已经生成mysql.sock。然后启动mysql
service mysql start