OFFLINE_HARD won't drop connections immediately

[Yuehhsun Ho]

From the document: "when a server is put into OFFLINE_HARD mode, no new connections are created toward that server and the existing connections are immediately dropped." 

so it seems like the ConnUsed will be zero immediately?

but when I do the following steps:

0. There are two DBs, A and B. and there's an application connects to A

1. Add two DBs to proxysql's mysql_servers tables and made sure all settings were correct (monitoring worked, listening port was correct), A is status=ONLINE, B is status=OFFLINE_HARD.

2. Enable binlog replication from A to B.

3. Set the A's status to 'OFFLINE_HARD', and B's to 'ONLINE'

After the step 3, I sent request to the application, but found the following error:

it lasted for ~25 secs.

2024-02-29 05:48:31 MySQL_Session.cpp:4229:handler_ProcessingQueryError_CheckBackendConnectionStatus(): [ERROR] Detected an offline server during query: db.a.url, 3306

17

2024-02-29 05:48:34 MySQL_Session.cpp:3174:handler_again___status_CHANGING_AUTOCOMMIT(): [ERROR] Detected a broken connection while during SET AUTOCOMMIT on (1,db.a.url,3306,1930055) , user db_a_user , last_used 154077825ms ago : 9004, Detected offline server prior to statement execution

Is it normal to have this waiting time for all the connections to drop?

Thank you for your help!

[René Cannaò]

Hi Yuehhsun,

In the error log you should have seen a warning like the following:

Removed server at address %lld, hostgroup %s, address %s port %s. Setting status OFFLINE HARD and immediately dropping all free connections. Used connections will be dropped when trying to use them

This should answer your question.

Although I don't think the documentation is incorrect, I will now update it to make it more specific.

Thanks,

René

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