[MDEV-7583] Connection stuck in "login" when I set wsrep_cluster_address='gcomm://' Created: 2015-02-13  Updated: 2015-02-18  Resolved: 2015-02-18

Status: Closed
Project: MariaDB Server
Component/s: Galera
Affects Version/s: 10.0.14-galera
Fix Version/s: 10.0.16-galera

Type: Bug Priority: Major
Reporter: Kolbe Kegel (Inactive) Assignee: Nirbhay Choubey (Inactive)
Resolution: Cannot Reproduce Votes: 0
Labels: None


 Description   

May be already fixed, but I thought I'd file it to get it written down somewhere.

I was running a 3-node cluster on 3 separate VMs.

I had a bash loop

while :; do mysql -e "insert..."; sleep 1; done

I killed 2 of the VMs (but left the one running that my bash loop connected to). The remaining note formed a new non-primary component as expected. I did SET GLOBAL wsrep_cluster_address='gcomm://' to make the remaining cluster node primary. But the client started by the bash loop got stuck for quite a long time (10+ minutes?):

| 737 | unauthenticated user | connecting host | NULL | Connect | NULL | login              | NULL             |    0.000 |

I tried to kill the thread, but it stays in "Killed":

| 737 | unauthenticated user | connecting host | NULL | Killed  | NULL | login              | NULL             |    0.000 |

Even killing the mysql process itself that's trying to connect doesn't make this MySQL thread go away.

So, it looks like there is some race condition that can cause a client to get stuck perhaps permanently in "login" when wsrep is trying to change the node/cluster state in some way.



 Comments   
Comment by Kolbe Kegel (Inactive) [ 2015-02-13 ]

This was pretty easy to reproduce on 10.0.14, but I haven't seen it yet on 10.0.16, so maybe it's fixed ...

Comment by Nirbhay Choubey (Inactive) [ 2015-02-18 ]

Doesn't reproduce with 10.0.16-galera.

Inserting row 19..
ERROR 1047 (08S01) at line 1: WSREP has not yet prepared node for application use

real 0m0.005s
user 0m0.004s
sys 0m0.000s

Inserting row 20..
ERROR 1047 (08S01) at line 1: WSREP has not yet prepared node for application use

real 0m0.019s
user 0m0.009s
sys 0m0.005s

Inserting row 21..

real 0m0.040s
user 0m0.013s
sys 0m0.000s

Inserting row 22..

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