Question :
My MariaDB replication stuck at ‘preparing’.
This happend after an update and restart of the server yesterday. Since then, replication is not working.
Setup: 2 MariaDB servers with master-master replication. Version: 10.4 (Upgraded few weeks ago from 10.1 – replication has worked after upgrade)
Since the output of both servers for SHOW SLAVE STATUS is similar, i am posting only from my first server:
MariaDB [(none)]> show slave statusG;
*************************** 1. row ***************************
Slave_IO_State: NULL
Master_Host: data2
Master_User: replusr
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mariadb-bin.018865
Read_Master_Log_Pos: 14137515
Relay_Log_File: relay-bin.017274
Relay_Log_Pos: 4
Relay_Master_Log_File: mariadb-bin.018865
Slave_IO_Running: Preparing
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 14137515
Relay_Log_Space: 768
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: NULL
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 2
Master_SSL_Crl:
Master_SSL_Crlpath:
Using_Gtid: No
Gtid_IO_Pos:
Replicate_Do_Domain_Ids:
Replicate_Ignore_Domain_Ids:
Parallel_Mode: conservative
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it
Slave_DDL_Groups: 0
Slave_Non_Transactional_Groups: 0
Slave_Transactional_Groups: 0
1 row in set (0.000 sec)
ERROR: No query specified
Logs aren’t showing anything and binaries are exploding since they cannot be rotated because the replication won’t continue.
I’ve never seen something like that. Any ideas?
EDIT – How to downgrade to previous version:
This seems to be a bigger problem. See: https://downloads.mariadb.org/mariadb/10.4.6/
For all the others who have the same problem, follow these steps to downgrade (I’ll give an example for 10.4.6, since this was my case):
Find the version you have used before and the related source: https://downloads.mariadb.org/mariadb/10.4.6/
After that, add it to your /etc/apt/sources.list:
deb [arch=amd64,ppc64el,arm64] http://mirrors.n-ix.net/mariadb/mariadb-10.4.6/repo/ubuntu/ xenial main
Downgrade:
apt install mariadb-server=1:10.4.6+maria~xenial mariadb-server-10.4=1:10.4.6+maria~xenial mariadb-client=1:10.4.6+maria~xenial mariadb-client-10.4=1:10.4.6+maria~xenial mariadb-server-core-10.4=1:10.4.6+maria~xenial mariadb-client-core-10.4=1:10.4.6+maria~xenial mysql-common=1:10.4.6+maria~xenial mariadb-client=1:10.4.6+maria~xenial libmariadb3=1:10.4.6+maria~xenial
Hold packages from upgrade, until fix is published:
apt-mark hold mariadb-server*
The steps are also explained here: https://jira.mariadb.org/browse/MDEV-20247?focusedCommentId=132114&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-132114
Answer :
I also had the same issue using Mariadb 10.4 master-slave replication.
I was using the setting innodb_thread_concurrency in the config file with a non-zero value. I updated it to:
innodb_thread_concurrency = 0
And now it’s working again.