OpenJDK 64-Bit Server VM warning: If the number of processors is expected to increase from one......

启动kafka的脚本程序报如下所示的错误：

OpenJDK 64-Bit Server VM warning: If the number of processors is expected to increase from one, then you should configure the number of parallel GC threads appropriately using -XX:ParallelGCThreads=N
[2020-05-15 01:57:53,870] WARN Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect (org.apache.zookeeper.ClientCnxn)
java.net.ConnectException: Connection refused
        at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
        at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
        at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:361)
        at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1141)
[2020-05-15 01:57:54,974] WARN Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect (org.apache.zookeeper.ClientCnxn)
java.net.ConnectException: Connection refused
        at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
        at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
        at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:361)
        at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1141)
[2020-05-15 01:57:56,077] WARN Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect (org.apache.zookeeper.ClientCnxn)
java.net.ConnectException: Connection refused
        at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
        at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
        at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:361)
        at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1141)

如遇到此报错，据错误分析，是zookeeper的问题，之前启动zookeeper集群，虚拟机重启后zookeeper的服务就停止了，Kafka依赖于Zookeeper，所以先启动zookeeper服务，然后启动kafka服务解决问题！！！

在zookeeper/bin目录下执行命令如下

[root@zookeeper1 bin]# ./zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /root/zookeeper-3.4.14/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED

//查看zookeeper服务的状态
[root@zookeeper1 bin]# ./zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /root/zookeeper-3.4.14/bin/../conf/zoo.cfg

至此，报错解决完成