[#MXS-4679] Binlog Router replication breaks without semi-sync set on Primary

I'm running MaxScale 23.02.2 and it's connected to a Mariadb 10.3.38. Both hosts are on Debian Buster.

If rpl_semi_sync_master_enabled is set to false on the primary, replication between MaxScale's binlogrouter and the primary will break within 5 minutes.

2023-07-21 10:57:02   error  : (binlogservice); Error received during replication from 'primary:3306': Failed to fetch binlog event from master:

2023-07-21 17:58:02 86422 [Warning] Aborted connection 86422 to db: 'unconnected' user: 'user' host: 'maxscale' (Got an error writing communication packets)

If I enable rpl_semi_sync_master_enabled, replication works as expected.

The Binlogrouter docs state that semi-sync isn't supported.

My MaxScale config looks like this.

[maxscale]

threads = auto

[binlogservice]

type=service

router=binlogrouter

servers=master

user=user

password=password

server_id=3489044470

datadir=/data/binlogs

expire_log_duration=72h

expire_log_minimum_files=3

net_timeout=30s

[master]

type=server

address=192.168.1.1

port=3306

protocol=MariaDBBackend

[binloglistener]

type=listener

service=binlogservice

protocol=mariadbprotocol

port=3306

address=0.0.0.0

[replicationmonitor]

type=monitor

module=mariadbmon

servers=master

user=user

password=password

monitor_interval=2000ms

The primary's settings are almost entirely the default

MariaDB [(none)]> show variables like '%binl%';

+-----------------------------------------+------------------------------+

| Variable_name                           | Value                        |

+-----------------------------------------+------------------------------+

| binlog_annotate_row_events              | ON                           |

| binlog_cache_size                       | 32768                        |

| binlog_checksum                         | CRC32                        |

| binlog_commit_wait_count                | 0                            |

| binlog_commit_wait_usec                 | 100000                       |

| binlog_direct_non_transactional_updates | OFF                          |

| binlog_file_cache_size                  | 16384                        |

| binlog_format                           | ROW                          |

| binlog_optimize_thread_scheduling       | ON                           |

| binlog_row_image                        | FULL                         |

| binlog_stmt_cache_size                  | 32768                        |

| encrypt_binlog                          | OFF                          |

| gtid_binlog_pos                         | 0-3489044454-12664560        |

| gtid_binlog_state                       | 0-1-44,0-3489044454-12664560 |

| innodb_locks_unsafe_for_binlog          | OFF                          |

| max_binlog_cache_size                   | 18446744073709547520         |

| max_binlog_size                         | 104857600                    |

| max_binlog_stmt_cache_size              | 18446744073709547520         |

| read_binlog_speed_limit                 | 0                            |

| sync_binlog                             | 0                            |

| wsrep_forced_binlog_format              | NONE                         |

+-----------------------------------------+------------------------------+

21 rows in set (0.002 sec)

MariaDB [(none)]> show variables like '%repl%';

+----------------------------------+-----------+

| Variable_name                    | Value     |

+----------------------------------+-----------+

| innodb_replication_delay         | 0         |

| replicate_annotate_row_events    | ON        |

| replicate_do_db                  |           |

| replicate_do_table               |           |

| replicate_events_marked_for_skip | REPLICATE |

| replicate_ignore_db              |           |

| replicate_ignore_table           |           |

| replicate_wild_do_table          |           |

| replicate_wild_ignore_table      |           |

| skip_parallel_replication        | OFF       |

| skip_replication                 | OFF       |

| wsrep_mysql_replication_bundle   | 0         |

| wsrep_replicate_myisam           | OFF       |

+----------------------------------+-----------+

13 rows in set (0.002 sec)

MariaDB [(none)]> show variables like '%rpl%';

+---------------------------------------+--------------+

| Variable_name                         | Value        |

+---------------------------------------+--------------+

| rpl_semi_sync_master_enabled          | OFF          |

| rpl_semi_sync_master_timeout          | 10000        |

| rpl_semi_sync_master_trace_level      | 32           |

| rpl_semi_sync_master_wait_no_slave    | ON           |

| rpl_semi_sync_master_wait_point       | AFTER_COMMIT |

| rpl_semi_sync_slave_delay_master      | OFF          |

| rpl_semi_sync_slave_enabled           | OFF          |

| rpl_semi_sync_slave_kill_conn_timeout | 5            |

| rpl_semi_sync_slave_trace_level       | 32           |

+---------------------------------------+--------------+

[MXS-4679] Binlog Router replication breaks without semi-sync set on Primary Created: 2023-07-21 Updated: 2023-08-15 Resolved: 2023-08-15
Status:	Closed
Project:	MariaDB MaxScale
Component/s:	binlogrouter
Affects Version/s:	23.02.2
Fix Version/s:	N/A

[MXS-4679] Binlog Router replication breaks without semi-sync set on Primary Created: 2023-07-21 Updated: 2023-08-15 Resolved: 2023-08-15