说明
RocketMQ中当重试消息超过最大重试次数（默认16次），会被发送到%DLQ%开头的死信队列，默认死信队列为只写权限。在有些情况下，想看看死信队列里的内容。
1.更改死信队列权限
bin/mqadmin updateTopicPerm -c ClusterB -t %DLQ%online-tst -p 6 -n 192.168.1.x:9876Java HotSpot(TM) 64-Bit Server VM warning: ignoring option PermSize=128m; support was removed in 8.0Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=128m; support was removed in 8.0update topic perm from 2 to 6 in 192.168.1.x:10911 success.update topic perm from 2 to 6 in 192.168.1.x:10911 success.update topic perm from 2 to 6 in 192.168.1.x:10911 success.update topic perm from 2 to 6 in 192.168.1.x:10911 success.
注：将死信队列只写权限更改为读写权限
2.查询死信队列状态
bin/mqadmin topicStatus -n 192.168.1.x:9876 -t %DLQ%online-tstJava HotSpot(TM) 64-Bit Server VM warning: ignoring option PermSize=128m; support was removed in 8.0Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=128m; support was removed in 8.0Broker Name QID Min Offset Max Offset Last Updatedbroker-a 0 0 109 -12-10 18:03:08,732broker-a 1 0 109 -12-10 18:03:08,740broker-a 2 0 110 -12-10 18:03:08,750broker-a 3 0 109 -12-10 18:03:08,728
3.根据offset查询消息内容
bin/mqadmin queryMsgByOffset -n localhost:9876 -t %DLQ%online-tst -b broker-a -i 0 -o 108Java HotSpot(TM) 64-Bit Server VM warning: ignoring option PermSize=128m; support was removed in 8.0Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=128m; support was removed in 8.0OffsetID: 0A090F2800002A9F000000D70519DD35OffsetID: 0A090F2800002A9F000000D70519DD35Topic: %DLQ%online-tstTags: [null]Keys: [null]Queue ID: 0Queue Offset: 108CommitLog Offset: 923503549749Reconsume Times: 0Born Timestamp: -12-10 17:59:24,731Store Timestamp: -12-10 18:03:08,732Born Host: 10.10.128.183:51889Store Host: 10.9.15.40:10911System Flag: 0Properties: {MIN_OFFSET=0, MAX_OFFSET=109, UNIQ_KEY=0A0A80B78DE818B4AAC22FA2493B01B2, WAIT=true}Message Body Path: /tmp/rocketmq/msgbodys/0A0A80B78DE818B4AAC22FA2493B01B2
注：使用打印命令消息临时存储在/tmp/rocketmq/msgbodys
4.查看消息内容
cat /tmp/rocketmq/msgbodys/0A0A80B78DE818B4AAC22FA2490F01AEHello RocketMQ430
