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Posted to users@activemq.apache.org by t-watana <wa...@jp.fujitsu.com> on 2018/06/15 09:51:52 UTC

the useless commands are written into KahaDB when the durable subscriber is destroyed by "offline timeout"

Hi all, I use ActiveMQ 5.13.1 for MQTT. 
It seems that ActivMQ writes some useless commands, when the durable 
subscriber 
 is destroyed by Offline Timeout. 

For example, the following situation: 

- Topic a, b, c 
- Durable Subscriber A, B, C 
- "Durable Subscriber A" subscribe ONLY "Topic a" 
- "Durable Subscriber B" subscribe ONLY "Topic b" 
- "Durable Subscriber C" subscribe ONLY "Topic c" 

When "Durable Subscriber A" is destroyed by Offline Timeout, ActiveMQ writes 
the following three KAHA_SUBSCRIPTION_COMMANDs. 

-KAHA_SUBSCRIPTION_COMMAND - TOPIC (DestId: 1:a), SubKey: A:EXACTLY_ONCE:A. 
-KAHA_SUBSCRIPTION_COMMAND - TOPIC (DestId: 1:b), SubKey: A:EXACTLY_ONCE:A.   
-KAHA_SUBSCRIPTION_COMMAND - TOPIC (DestId: 1:c), SubKey: A:EXACTLY_ONCE:A. 

I think, the first command is necessary but the others are not 

Don't you think that it should be checked and written whether the "durable 
subscriber" is actually subscribing the topic ? 




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