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MDEV-16146: MariaDB slave stops with following errors.

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Problem:
========
180511 11:07:58 [ERROR] Slave I/O: Unexpected master's heartbeat data:
heartbeat is not compatible with local info;the event's data: log_file_name
mysql-bin.000009 log_pos 1054262041, Error_code: 1623

Analysis:
=========
In replication setup when master server doesn't have any events to send to
slave server it sends an 'Heartbeat_log_event'. This event carries the
current binary log filename and offset details. The offset values is stored
within 4 bytes of event header. When the size of binary log is higher than
UINT32_MAX the log_pos values will not fit in 4 bytes memory.  It overflows
and hence slave stops with an error.

Fix:
===
Since we cannot extend the common_header of Log_event class, a greater than
4GB value of Log_event::log_pos is made to be transported with a HeartBeat
event's sub-header.  Log_event::log_pos in such case is set to zero to
indicate that the 8 byte sub-header is allocated in the event.

In case of cross version replication following behaviour is expected

OLD - Server without fix
NEW - Server with fix

OLD<->NEW : works bidirectionally as long as the binlog offset is
            (normally) within 4GB.

When log_pos > UINT32_MAX
OLD->NEW  : The 'log_pos' is bound to overflow and NEW slave may report
            an invalid event/incompatible heart beat event error.
NEW->OLD  : Since patched server sets log_pos=0 on overflow, OLD slave will
            report invalid event error.
This commit is contained in:
Sujatha
2021-04-30 18:12:43 +05:30
parent 13b9af50e4
commit abe6eb10a6
5 changed files with 112 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
mysql-test/suite/rpl/r/rpl_incompatible_heartbeat.result Normal file
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@@ -0,0 +1,17 @@
include/master-slave.inc
[connection master]
connection master;
SET @saved_dbug = @@GLOBAL.debug_dbug;
SET @@global.debug_dbug= 'd,simulate_pos_4G';
connection slave;
include/stop_slave.inc
CHANGE MASTER TO MASTER_HEARTBEAT_PERIOD=0.001;
include/start_slave.inc
connection master;
SET @@GLOBAL.debug_dbug = @saved_dbug;
connection slave;
connection master;
CREATE TABLE t (f INT) ENGINE=INNODB;
INSERT INTO t VALUES (10);
DROP TABLE t;
include/rpl_end.inc

44
mysql-test/suite/rpl/t/rpl_incompatible_heartbeat.test Normal file
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@@ -0,0 +1,44 @@
# ==== Purpose ====
#
# Test verifies that slave IO thread can process heartbeat events with log_pos
# values higher than UINT32_MAX.
#
# ==== Implementation ====
#
# Steps:
# 0 - Stop slave threads. Configure a small master_heartbeat_period.
# 1 - Using debug points, simulate a huge binlog offset higher than
# UINT32_MAX on master.
# 2 - Start the slave and observe that slave IO thread is able to process
# the offset received through heartbeat event.
#
# ==== References ====
#
# MDEV-16146: MariaDB slave stops with incompatible heartbeat
#
--source include/have_debug.inc
--source include/have_innodb.inc
--source include/have_binlog_format_mixed.inc
# Test simulates binarylog offsets higher than UINT32_MAX
--source include/have_64bit.inc
--source include/master-slave.inc
--connection master
SET @saved_dbug = @@GLOBAL.debug_dbug;
SET @@global.debug_dbug= 'd,simulate_pos_4G';
--connection slave
--source include/stop_slave.inc
CHANGE MASTER TO MASTER_HEARTBEAT_PERIOD=0.001;
--source include/start_slave.inc
--connection master
sleep 1;
SET @@GLOBAL.debug_dbug = @saved_dbug;
--sync_slave_with_master
--connection master
CREATE TABLE t (f INT) ENGINE=INNODB;
INSERT INTO t VALUES (10);
DROP TABLE t;
--source include/rpl_end.inc