Admin login always takes >30 sec when using Redis on 2.2.1

[keithbentrup]

Preconditions

1. Magento 2.2.1
2. Redis for session management

Steps to reproduce

1. Login to the admin

Expected result

1. Login should be immediate

Actual result

1. Login takes >30 secs due to a recent commit that causes a new session id to be generated during the request

The regenerateId method was recently rewritten to generate a new session id when an admin logs into the admin dashboard.
The change in the session id causes the session read method of the redis session handling class to loop 60 times with a 500 ms sleep at the end of each loop before breaking out while it looks for the locking pid. This is because both session_regenerate_id and session_start increment the lock value 0->1->2 but only when the value is 1 will it break out otherwise it continues for $tries (60) with a 500 ms sleep between each one.

[Tjitse-E]

@magento-engcom-team is this issue already fixed on the development branche? If yes, can you point me to the right commit?

[mslabko]

Hi @Tjitse-E, fix will be available in the nearest release. For now you can take it from 2.2-develop branch: aaa60b1

[ishakhsuvarov]

@mslabko @Tjitse-E @keithbentrup Closing this ticket for now as fix is available in 2.2.2 and delivered with the linked commit.
Thank you for collaboration.

[tuyennn]

#12362