解决rocket客户端：maybe your broker machine memory too small

1. 问题：

org.apache.rocketmq.client.exception.MQClientException: Send [3] times, still failed, cost [34]ms, Topic: wechat_message_send_topic, BrokersSent: [PC-20090106MWGS, PC-20090106MWGS, PC-20090106MWGS]
See http://rocketmq.apache.org/docs/faq/ for further details.
    at org.apache.rocketmq.client.impl.producer.DefaultMQProducerImpl.sendDefaultImpl(DefaultMQProducerImpl.java:665) ~[rocketmq-client-4.7.1.jar:4.7.1]
    at org.apache.rocketmq.client.impl.producer.DefaultMQProducerImpl.send(DefaultMQProducerImpl.java:1343) ~[rocketmq-client-4.7.1.jar:4.7.1]
    at org.apache.rocketmq.client.impl.producer.DefaultMQProducerImpl.send(DefaultMQProducerImpl.java:1289) ~[rocketmq-client-4.7.1.jar:4.7.1]
    at org.apache.rocketmq.client.producer.DefaultMQProducer.send(DefaultMQProducer.java:325) ~[rocketmq-client-4.7.1.jar:4.7.1] 
    at com.alibaba.dubbo.common.bytecode.Wrapper120.invokeMethod(Wrapper120.java) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.proxy.javassist.JavassistProxyFactory$1.doInvoke(JavassistProxyFactory.java:46) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.proxy.AbstractProxyInvoker.invoke(AbstractProxyInvoker.java:72) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.protocol.InvokerWrapper.invoke(InvokerWrapper.java:53) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.filter.ExceptionFilter.invoke(ExceptionFilter.java:64) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:69) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.monitor.support.MonitorFilter.invoke(MonitorFilter.java:75) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:69) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.filter.TimeoutFilter.invoke(TimeoutFilter.java:42) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:69) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.protocol.dubbo.filter.TraceFilter.invoke(TraceFilter.java:78) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:69) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.filter.ContextFilter.invoke(ContextFilter.java:61) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:69) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.filter.GenericFilter.invoke(GenericFilter.java:132) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:69) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.filter.ClassLoaderFilter.invoke(ClassLoaderFilter.java:38) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:69) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.filter.EchoFilter.invoke(EchoFilter.java:38) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:69) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.rpc.protocol.dubbo.DubboProtocol$1.reply(DubboProtocol.java:102) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.handleRequest(HeaderExchangeHandler.java:98) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.received(HeaderExchangeHandler.java:170) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.remoting.transport.DecodeHandler.received(DecodeHandler.java:52) [dubbo-2.5.5.jar:2.5.5]
    at com.alibaba.dubbo.remoting.transport.dispatcher.ChannelEventRunnable.run(ChannelEventRunnable.java:81) [dubbo-2.5.5.jar:2.5.5]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_131]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_131]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_131]
Caused by: org.apache.rocketmq.client.exception.MQBrokerException: CODE: 14  DESC: service not available now, maybe disk full, CL:  0.94 CQ:  0.94 INDEX:  0.94, maybe your broker machine memory too small.
For more information, please visit the url, http://rocketmq.apache.org/docs/faq/
    at org.apache.rocketmq.client.impl.MQClientAPIImpl.processSendResponse(MQClientAPIImpl.java:665) ~[rocketmq-client-4.7.1.jar:4.7.1]
    at org.apache.rocketmq.client.impl.MQClientAPIImpl.sendMessageSync(MQClientAPIImpl.java:505) ~[rocketmq-client-4.7.1.jar:4.7.1]
    at org.apache.rocketmq.client.impl.MQClientAPIImpl.sendMessage(MQClientAPIImpl.java:487) ~[rocketmq-client-4.7.1.jar:4.7.1]
    at org.apache.rocketmq.client.impl.MQClientAPIImpl.sendMessage(MQClientAPIImpl.java:431) ~[rocketmq-client-4.7.1.jar:4.7.1]
    at org.apache.rocketmq.client.impl.producer.DefaultMQProducerImpl.sendKernelImpl(DefaultMQProducerImpl.java:854) ~[rocketmq-client-4.7.1.jar:4.7.1]
    at org.apache.rocketmq.client.impl.producer.DefaultMQProducerImpl.sendDefaultImpl(DefaultMQProducerImpl.java:584) ~[rocketmq-client-4.7.1.jar:4.7.1]
    ... 33 common frames omitted

2.原因：
磁盘空间不足，导致mq停止接收消息
rocketMQ的diskSpaceWarningLevelRatio 磁盘空间警戒阈值，超过这个值则停止接受消息，默认值90

3.解决办法：
方式一、清理磁盘空间
方式二、 修改 runbroker.sh，在里面增加一句话即可：
JAVA_OPT="${JAVA_OPT} -Drocketmq.broker.diskSpaceWarningLevelRatio=0.98"
我这里把磁盘保护的百分比设置成98%，只有磁盘空间使用率达到98%时才拒绝接收producer消息。