rocketmq 记
Rocketmq选型
Rocket是一个专业的队列服务，性能优于Rabbitmq，优势是性能和并发，源于Kafka的扩展版，增强了数据的可靠性。
Rocketmq的队列类型
普通队列，广播队列、顺序队列，分区顺序
2、同步机制
Rocketmq使用主从同步模式，同步分为同步和异步模式，这和mysql类似。
3、Rocketmq管理命令
rocketmq也可以通过web管理，坑中有说
创建topic
bin/mqadmin updateTopic -n '192.168.1.64:9876;192.168.1.107:9876' -c DefaultCluster -t tt -w 5 -r 5 -o=true #-o=true是有序队列
Rocketmq坑
1、rocketmq 在本地搭建环境启动时，内存溢出报了内存错误：
# There is insufficient memory for the Java Runtime Environment to continue.
# Native memory allocation (mmap) failed to map 8589934592 bytes for committing reserved memory.
解决方法：修改bin/runbroker.sh,bin/runserver.sh
-server -Xms1g -Xmx1g -Xmn1g -XX:MetaspaceSize=128m -XX:MaxMetaspaceSize=320m
内存大的虚拟机没问题，像我这渣渣笔记本，得节省点啊！
2、Rocketmq管理web
https://github.com/apache/rocketmq-externals/tree/master/rocketmq-console
下载安装Console项目
Rocketmq的普通队列、顺序队列、分区顺序队列、广播消息实现、事务队列
https://www.jianshu.com/p/3afd610a8f7d
https://www.jianshu.com/p/790d6bc4a1c1
https://www.jianshu.com/p/53324ea2df92
我遇到的坑
阿里云上面买的RocketMq和开源版本的Rocketmq的sdk不同，有着兼容问题。我们有一个自己机房和阿里的共用运行的服务，这时候发现只能在阿里机房上布，而在本地机房看来只能再写一套抽象层了，这非常不友好。使用了阿里的 Rocketmq也就意味着你的程序移植不到其它云或服务器上了。
slave 修改：
1、内存优化
bin/runbroker.sh MaxDirectMemorySize =15g 改成1g
2、host解析失败
在rocketmq的主从是通过获取hostname然后解析host到ip上进行互相访问的，所以需要将各机器的hosts增加解析
192.168.1.102 localhost.ceontsPHP
192.168.1.101 localhost.bobby
hostname可以通过各服务器的/etc/hostsname查看
rocket会报错:rocketmq Failed to obtain the host name
3、锁文件冲突原因
因为rocketmq设计一个用户运行一个示例，一个用户锁定了一个用户store存储目录，所以在一起运行会冲突,提示：Lock failed,MQ already startedz
解决方法是每个示例使用一个用户
或
broker.conf 指定 storePathRootDir目录
4、端口会冲突
不同broker需使用不同端口，如果不是root用户，端口号应该是1024+
一个broker不仅仅使用你指定的listenPort，上下最好空几个，比如指定1081端口，他还占用了1079 1081 1082
5、配置文件坑
我直接拿官方配置文件2m-2s-async下的配置，不行，没有提示，就是执行clusterList时，没有集群，这很坑，然后我自己建配置文件成功
bin/mqbroker -c /root/rocketmq/release/conf/2m-2s-async/broker-a-s.properties > a.log 2>&1
bin/mqadmin clusterList -n centos:9876
bin/mqadmin updateTopic -n 'centos:9876' -c mycluster -t tt -w 5 -r 5 -o=true
# broker a
namesrvAddr=centos:9876
brokerIP1=192.168.56.101
brokerName=broker-a
brokerClusterName=mycluster
brokerId=0
listenPort=1081
autoCreateTopicEnable=true
autoCreateSubscriptionGroup=true
rejectTransactionMessage=false
fetchNamesrvAddrByAddressServer=false
storePathRootDir=/root/storeA
storePathCommitLog=/root/store/commitlog
flushIntervalCommitLog=500
commitIntervalCommitLog=200
flushCommitLogTimed=false
deleteWhen=04
fileReservedTime=48
maxTransferBytesOnMessageInMemory=262144
maxTransferCountOnMessageInMemory=32
maxTransferBytesOnMessageInDisk=65536
maxTransferCountOnMessageInDisk=8
accessMessageInMemoryMaxRatio=40
messageIndexEnable=true
messageIndexSafe=false
haMasterAddress=
brokerRole=ASYNC_MASTER
flushDiskType=ASYNC_FLUSH
cleanFileForciblyEnable=true
transientStorePoolEnable=false
#broker a-s
namesrvAddr=centos:9876
brokerIP1=192.168.56.102
brokerName=broker-a
brokerClusterName=mycluster
brokerId=1
listenPort=1091
autoCreateTopicEnable=true
autoCreateSubscriptionGroup=true
rejectTransactionMessage=false
fetchNamesrvAddrByAddressServer=false
storePathRootDir=/root/storeAs
storePathCommitLog=/root/store/commitlog
flushIntervalCommitLog=500
commitIntervalCommitLog=200
flushCommitLogTimed=false
deleteWhen=04
fileReservedTime=48
maxTransferBytesOnMessageInMemory=262144
maxTransferCountOnMessageInMemory=32
maxTransferBytesOnMessageInDisk=65536
maxTransferCountOnMessageInDisk=8
accessMessageInMemoryMaxRatio=40
messageIndexEnable=true
messageIndexSafe=false
haMasterAddress=
brokerRole=SLAVE
flushDiskType=ASYNC_FLUSH
cleanFileForciblyEnable=true
transientStorePoolEnable=false
#broker b
namesrvAddr=centos:9876
brokerIP1=192.168.56.101
brokerName=broker-b
brokerClusterName=mycluster
brokerId=0
listenPort=1085
autoCreateTopicEnable=true
autoCreateSubscriptionGroup=true
rejectTransactionMessage=false
fetchNamesrvAddrByAddressServer=false
storePathRootDir=/root/storeB
storePathCommitLog=/root/store/commitlog
flushIntervalCommitLog=500
commitIntervalCommitLog=200
flushCommitLogTimed=false
deleteWhen=04
fileReservedTime=48
maxTransferBytesOnMessageInMemory=262144
maxTransferCountOnMessageInMemory=32
maxTransferBytesOnMessageInDisk=65536
maxTransferCountOnMessageInDisk=8
accessMessageInMemoryMaxRatio=40
messageIndexEnable=true
messageIndexSafe=false
haMasterAddress=
brokerRole=ASYNC_MASTER
flushDiskType=ASYNC_FLUSH
cleanFileForciblyEnable=true
transientStorePoolEnable=false
#broker b-s
namesrvAddr=centos:9876
brokerIP1=192.168.56.102
brokerName=broker-b
brokerClusterName=mycluster
brokerId=1
listenPort=1095
autoCreateTopicEnable=true
autoCreateSubscriptionGroup=true
rejectTransactionMessage=false
fetchNamesrvAddrByAddressServer=false
storePathRootDir=/root/storeBs
storePathCommitLog=/root/store/commitlog
flushIntervalCommitLog=500
commitIntervalCommitLog=200
flushCommitLogTimed=false
deleteWhen=04
fileReservedTime=48
maxTransferBytesOnMessageInMemory=262144
maxTransferCountOnMessageInMemory=32
maxTransferBytesOnMessageInDisk=65536
maxTransferCountOnMessageInDisk=8
accessMessageInMemoryMaxRatio=40
messageIndexEnable=true
messageIndexSafe=false
haMasterAddress=
brokerRole=SLAVE
flushDiskType=ASYNC_FLUSH
cleanFileForciblyEnable=true
transientStorePoolEnable=false
rocketmq sdk使用newFixThreadPool线程池用于获取server中的数据(线程数获取的cpu核心数)，拿到消息后，submit 给->ThreadPoolExecutor线程池进行执行消费，执行消费可以指定最大线程数和最小线程数。
rocketmq多消费端是需要通过tag指定的，如果你想和使用rabbitmq一样使用，可能会疯，百度搜出来的鸡八狗屁文章，根本狗屁不通。
rocketmq 存储结构:
https://blog.csdn.net/mr253727942/article/details/55805876
IO调度方式：
https://www.cnblogs.com/cobbliu/p/5389556.html
