pxc_maint_mode is removing node immediately at shutdown.

[altmannmarcelo]

ProxySQL 2.0.9 introduced the awareness of pxc_maint_mode. This is meant to allow for already established connections to finish its work.
PXC changes and expose this variable as follow:

• Change to SHUTDOWN - It changes the value of pxc_maint_mode to SHUTDOWN immediately and sleep for pxc_maint_transition_period prior to starting the shutdown.
• Change to MAINTENANCE - It changes the value of pxc_maint_mode to MAINTENANCE immediately.

ProxySQL is removing the server immediately instead of marking it as OFFLINE_SOFT, which despite the purpose of the feature.

How to reproduce:

Setup: 3PXC nodes, single writer.

• Connect on proxysql via 6033 port (will name it CNX1)
• CNX1: run START TRANSACTION and leave the terminal open
• Connect directly on wirter (will name it CNX2)
• CNX2: Change the maint period to 30 seconds SET GLOBAL pxc_maint_transition_period = 30;
• stop mysql on writer (service mysql stop) . This will hang for 30 seconds before initiating the shutdown
• CNX1: execute any query, such as SELECT SLEEP(1). At this point, you will receive:

ERROR 2013 (HY000): Lost connection to MySQL server during query

You can validate that the server is still up by execting a new connection directly to the writer.

The same issue happens when changing pxc_maint_mode to MAINTENANCE, all open connections (with multiplexing disabled) are closed immediately.

[renecannao]

Fixed in 2.0.10