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mariadb/mysql-test/suite/rpl/r/rpl_semi_sync.result
Michael Widenius 7af50e4df4 MDEV-32551: "Read semi-sync reply magic number error" warnings on master 
rpl_semi_sync_slave_enabled_consistent.test and the first part of
the commit message comes from Brandon Nesterenko.

A test to show how to induce the "Read semi-sync reply magic number
error" message on a primary. In short, if semi-sync is turned on
during the hand-shake process between a primary and replica, but
later a user negates the rpl_semi_sync_slave_enabled variable while
the replica's IO thread is running; if the io thread exits, the
replica can skip a necessary call to kill_connection() in
repl_semisync_slave.slave_stop() due to its reliance on a global
variable. Then, the replica will send a COM_QUIT packet to the
primary on an active semi-sync connection, causing the magic number
error.

The test in this patch exits the IO thread by forcing an error;
though note a call to STOP SLAVE could also do this, but it ends up
needing more synchronization. That is, the STOP SLAVE command also
tries to kill the VIO of the replica, which makes a race with the IO
thread to try and send the COM_QUIT before this happens (which would
need more debug_sync to get around). See THD::awake_no_mutex for
details as to the killing of the replica’s vio.

Notes:
- The MariaDB documentation does not make it clear that when one
  enables semi-sync replication it does not matter if one enables
  it first in the master or slave. Any order works.

Changes done:
- The rpl_semi_sync_slave_enabled variable is now a default value for
  when semisync is started. The variable does not anymore affect
  semisync if it is already running. This fixes the original reported
  bug.  Internally we now use repl_semisync_slave.get_slave_enabled()
  instead of rpl_semi_sync_slave_enabled. To check if semisync is
  active on should check the @@rpl_semi_sync_slave_status variable (as
  before).
- The semisync protocol conflicts in the way that the original
  MySQL/MariaDB client-server protocol was designed (client-server
  send and reply packets are strictly ordered and includes a packet
  number to allow one to check if a packet is lost). When using
  semi-sync the master and slave can send packets at 'any time', so
  packet numbering does not work. The 'solution' has been that each
  communication starts with packet number 1, but in some cases there
  is still a chance that the packet number check can fail.  Fixed by
  adding a flag (pkt_nr_can_be_reset) in the NET struct that one can
  use to signal that packet number checking should not be done. This
  is flag is set when semi-sync is used.
- Added Master_info::semi_sync_reply_enabled to allow one to configure
  some slaves with semisync and other other slaves without semisync.
  Removed global variable semi_sync_need_reply that would not work
  with multi-master.
- Repl_semi_sync_master::report_reply_packet() can now recognize
  the COM_QUIT packet from semisync slave and not give a
  "Read semi-sync reply magic number error" error for this case.
  The slave will be removed from the Ack listener.
- On Windows, don't stop semisync Ack listener just because one
  slave connection is using socket_id > FD_SETSIZE.
- Removed busy loop in Ack_receiver::run() by using
 "Self-pipe trick" to signal new slave and stop Ack_receiver.
- Changed some Repl_semi_sync_slave functions that always returns 0
  from int to void.
- Added Repl_semi_sync_slave::slave_reconnect().
- Removed dummy_function Repl_semi_sync_slave::reset_slave().
- Removed some duplicate semisync notes from the error log.
- Add test of "if (get_slave_enabled() && semi_sync_need_reply)"
  before calling Repl_semi_sync_slave::slave_reply().
  (Speeds up the code as we can skip all initializations).
- If epl_semisync_slave.slave_reply() fails, we disable semisync
  for that connection.
- We do not call semisync.switch_off() if there are no active slaves.
  Instead we check in Repl_semi_sync_master::commit_trx() if there are
  no active threads. This simplices the code.
- Changed assert() to DBUG_ASSERT() to ensure that the DBUG log is
  flushed in case of asserts.
- Removed the internal rpl_semi_sync_slave_status as it is not needed
  anymore. The @@rpl_semi_sync_slave_status status variable is now
  mapped to rpl_semi_sync_enabled.
- Removed rpl_semi_sync_slave_enabled  as it is not needed anymore.
  Repl_semi_sync_slave::get_slave_enabled() contains the active status.
- Added checking that we do not add a slave twice with
  Ack_receiver::add_slave(). This could happen with old code.
- Removed Repl_semi_sync_master::check_and_switch() as it is not
  needed anymore.
- Ensure that when we call Ack_receiver::remove_slave() that the slave
  is removed from the listener before function returns.
- Call listener.listen_on_sockets() outside of mutex for better
  performance and less contested mutex.
- Ensure that listening is ignoring newly added slaves when checking for
  responses.
- Fixed the master ack_receiver listener is not killed if there are no
  connected slaves (and thus stop semisync handling of future
  connections). This could happen if all slaves sockets where would be
  marked as unreliable.
- Added unlink() to base_ilist_iterator and remove() to
  I_List_iterator. This enables us to remove 'dead' slaves in
  Ack_recever::run().
- kill_zombie_dump_threads() now does killing of dump threads properly.
  - It can now kill several threads (should be impossible but could
    happen if IO slaves reconnects very fast).
  - We now wait until the dump thread is done before starting the
    dump.
- Added an error if kill_zombie_dump_threads() fails.
- Set thd->variables.server_id before calling
  kill_zombie_dump_threads(). This simplies the code.
- Added a lot of comments both in code and tests.
- Removed DBUG_EVALUATE_IF "failed_slave_start" as it is not used.

Test changes:
- rpl.rpl_session_var2 added which runs rpl.rpl_session_var test with
  semisync enabled.
- Some timings changed slight with startup of slave which caused
  rpl_binlog_dump_slave_gtid_state_info.text to fail as it checked the
  error log file before the slave had started properly. Fixed by
  adding wait_for_pattern_in_file.inc that allows waiting for the
  pattern to appear in the log file.
- Tests have been updated so that we first set
  rpl_semi_sync_master_enabled on the master and then set
  rpl_semi_sync_slave_enabled on the slaves (this is according to how
  the MariaDB documentation document how to setup semi-sync).
- Error text "Master server does not have semi-sync enabled" has been
  replaced with "Master server does not support semi-sync" for the
  case when the master supports semi-sync but semi-sync is not
  enabled.

Other things:
- Some trivial cleanups in Repl_semi_sync_master::update_sync_header().
- We should in 11.3 changed the default value for
  rpl-semi-sync-master-wait-no-slave from TRUE to FALSE as the TRUE
  does not make much sense as default. The main difference with using
  FALSE is that we do not wait for semisync Ack if there are no slave
  threads.  In the case of TRUE we wait once, which did not bring any
  notable benefits except slower startup of master configured for
  using semisync.

Co-author: Brandon Nesterenko <brandon.nesterenko@mariadb.com>

This solves the problem reported in MDEV-32960 where a new
slave may not be registered in time and the master disables
semi sync because of that.
2024-01-23 13:03:11 +02:00

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include/master-slave.inc
[connection master]
connection master;
call mtr.add_suppression("Timeout waiting for reply of binlog");
call mtr.add_suppression("Read semi-sync reply");
call mtr.add_suppression("Unsafe statement written to the binary log using statement format since BINLOG_FORMAT = STATEMENT.");
call mtr.add_suppression("mysqld: Got an error reading communication packets");
connection slave;
call mtr.add_suppression("Semi-sync slave .* reply");
call mtr.add_suppression("Slave SQL.*Request to stop slave SQL Thread received while applying a group that has non-transactional changes; waiting for completion of the group");
connection master;
#
# Uninstall semi-sync plugins on master and slave
#
connection slave;
include/stop_slave.inc
reset slave;
set global rpl_semi_sync_master_enabled= 0;
set global rpl_semi_sync_slave_enabled= 0;
connection master;
reset master;
set global rpl_semi_sync_master_enabled= 0;
set global rpl_semi_sync_slave_enabled= 0;
#
# Main test of semi-sync replication start here
#
connection master;
set global rpl_semi_sync_master_timeout= 2000;
[ default state of semi-sync on master should be OFF ]
show variables like 'rpl_semi_sync_master_enabled';
Variable_name Value
rpl_semi_sync_master_enabled OFF
[ enable semi-sync on master ]
set global rpl_semi_sync_master_enabled = 1;
show variables like 'rpl_semi_sync_master_enabled';
Variable_name Value
rpl_semi_sync_master_enabled ON
[ status of semi-sync on master should be ON even without any semi-sync slaves ]
show status like 'Rpl_semi_sync_master_clients';
Variable_name Value
Rpl_semi_sync_master_clients 0
show status like 'Rpl_semi_sync_master_status';
Variable_name Value
Rpl_semi_sync_master_status ON
show status like 'Rpl_semi_sync_master_yes_tx';
Variable_name Value
Rpl_semi_sync_master_yes_tx 0
#
# BUG#45672 Semisync repl: ActiveTranx:insert_tranx_node: transaction node allocation failed
# BUG#45673 Semisynch reports correct operation even if no slave is connected
#
[ status of semi-sync on master should be OFF ]
show status like 'Rpl_semi_sync_master_clients';
Variable_name Value
Rpl_semi_sync_master_clients 0
show status like 'Rpl_semi_sync_master_status';
Variable_name Value
Rpl_semi_sync_master_status OFF
show status like 'Rpl_semi_sync_master_yes_tx';
Variable_name Value
Rpl_semi_sync_master_yes_tx 0
reset master;
connection slave;
[ default state of semi-sync on slave should be OFF ]
show variables like 'rpl_semi_sync_slave_enabled';
Variable_name Value
rpl_semi_sync_slave_enabled OFF
[ enable semi-sync on slave ]
set global rpl_semi_sync_slave_enabled = 1;
show variables like 'rpl_semi_sync_slave_enabled';
Variable_name Value
rpl_semi_sync_slave_enabled ON
include/start_slave.inc
connection master;
[ initial master state after the semi-sync slave connected ]
show status like 'Rpl_semi_sync_master_clients';
Variable_name Value
Rpl_semi_sync_master_clients 1
show status like 'Rpl_semi_sync_master_status';
Variable_name Value
Rpl_semi_sync_master_status ON
show status like 'Rpl_semi_sync_master_no_tx';
Variable_name Value
Rpl_semi_sync_master_no_tx 0
show status like 'Rpl_semi_sync_master_yes_tx';
Variable_name Value
Rpl_semi_sync_master_yes_tx 0
create table t1(a int) engine = ENGINE_TYPE;
[ master state after CREATE TABLE statement ]
show status like 'Rpl_semi_sync_master_status';
Variable_name Value
Rpl_semi_sync_master_status ON
show status like 'Rpl_semi_sync_master_no_tx';
Variable_name Value
Rpl_semi_sync_master_no_tx 0
show status like 'Rpl_semi_sync_master_yes_tx';
Variable_name Value
Rpl_semi_sync_master_yes_tx 1
select CONNECTIONS_NORMAL_SLAVE - CONNECTIONS_NORMAL_SLAVE as 'Should be 0';
Should be 0
0
[ insert records to table ]
insert t1 values (10);
insert t1 values (9);
insert t1 values (8);
insert t1 values (7);
insert t1 values (6);
insert t1 values (5);
insert t1 values (4);
insert t1 values (3);
insert t1 values (2);
insert t1 values (1);
[ master status after inserts ]
show status like 'Rpl_semi_sync_master_status';
Variable_name Value
Rpl_semi_sync_master_status ON
show status like 'Rpl_semi_sync_master_no_tx';
Variable_name Value
Rpl_semi_sync_master_no_tx 0
show status like 'Rpl_semi_sync_master_yes_tx';
Variable_name Value
Rpl_semi_sync_master_yes_tx 11
connection slave;
[ slave status after replicated inserts ]
show status like 'Rpl_semi_sync_slave_status';
Variable_name Value
Rpl_semi_sync_slave_status ON
select count(distinct a) from t1;
count(distinct a)
10
select min(a) from t1;
min(a)
1
select max(a) from t1;
max(a)
10
# BUG#50157
# semi-sync replication crashes when replicating a transaction which
# include 'CREATE TEMPORARY TABLE `MyISAM_t` SELECT * FROM `Innodb_t` ;
connection master;
SET SESSION AUTOCOMMIT= 0;
CREATE TABLE t2(c1 INT) ENGINE=innodb;
connection slave;
connection master;
BEGIN;
# Even though it is in a transaction, this statement is binlogged into binlog
# file immediately.
CREATE TEMPORARY TABLE t3 SELECT c1 FROM t2 where 1=1;
# These statements will not be binlogged until the transaction is committed
INSERT INTO t2 VALUES(11);
INSERT INTO t2 VALUES(22);
COMMIT;
DROP TABLE t2, t3;
SET SESSION AUTOCOMMIT= 1;
connection slave;
#
# Test semi-sync master will switch OFF after one transaction
# timeout waiting for slave reply.
#
connection master;
show status like "Rpl_semi_sync_master_status";
Variable_name Value
Rpl_semi_sync_master_status ON
connection slave;
include/stop_slave.inc
connection master;
include/kill_binlog_dump_threads.inc
set global rpl_semi_sync_master_timeout= 2000;
[ master status should be ON ]
show status like 'Rpl_semi_sync_master_no_tx';
Variable_name Value
Rpl_semi_sync_master_no_tx 0
show status like 'Rpl_semi_sync_master_yes_tx';
Variable_name Value
Rpl_semi_sync_master_yes_tx 14
[ semi-sync replication of these transactions will fail ]
insert into t1 values (500);
[ master status should be OFF ]
show status like 'Rpl_semi_sync_master_status';
Variable_name Value
Rpl_semi_sync_master_status OFF
show status like 'Rpl_semi_sync_master_no_tx';
Variable_name Value
Rpl_semi_sync_master_no_tx 1
show status like 'Rpl_semi_sync_master_yes_tx';
Variable_name Value
Rpl_semi_sync_master_yes_tx 14
delete from t1 where a=10;
delete from t1 where a=9;
delete from t1 where a=8;
delete from t1 where a=7;
delete from t1 where a=6;
delete from t1 where a=5;
delete from t1 where a=4;
delete from t1 where a=3;
delete from t1 where a=2;
delete from t1 where a=1;
insert into t1 values (100);
[ master status should be OFF ]
show status like 'Rpl_semi_sync_master_status';
Variable_name Value
Rpl_semi_sync_master_status OFF
show status like 'Rpl_semi_sync_master_no_tx';
Variable_name Value
Rpl_semi_sync_master_no_tx 12
show status like 'Rpl_semi_sync_master_yes_tx';
Variable_name Value
Rpl_semi_sync_master_yes_tx 14
#
# Test semi-sync status on master will be ON again when slave catches up
#
connection slave;
[ slave status should be OFF ]
show status like 'Rpl_semi_sync_slave_status';
Variable_name Value
Rpl_semi_sync_slave_status OFF
include/start_slave.inc
[ slave status should be ON ]
show status like 'Rpl_semi_sync_slave_status';
Variable_name Value
Rpl_semi_sync_slave_status ON
select count(distinct a) from t1;
count(distinct a)
2
select min(a) from t1;
min(a)
100
select max(a) from t1;
max(a)
500
connection master;
[ master status should be ON again after slave catches up ]
show status like 'Rpl_semi_sync_master_no_tx';
Variable_name Value
Rpl_semi_sync_master_no_tx 12
show status like 'Rpl_semi_sync_master_yes_tx';
Variable_name Value
Rpl_semi_sync_master_yes_tx 14
show status like 'Rpl_semi_sync_master_clients';
Variable_name Value
Rpl_semi_sync_master_clients 1
#
# Test disable/enable master semi-sync on the fly.
#
drop table t1;
connection slave;
include/stop_slave.inc
#
# Flush status
#
connection master;
[ Semi-sync master status variables before FLUSH STATUS ]
SHOW STATUS LIKE 'Rpl_semi_sync_master_no_tx';
Variable_name Value
Rpl_semi_sync_master_no_tx 12
SHOW STATUS LIKE 'Rpl_semi_sync_master_yes_tx';
Variable_name Value
Rpl_semi_sync_master_yes_tx 15
FLUSH NO_WRITE_TO_BINLOG STATUS;
[ Semi-sync master status variables after FLUSH STATUS ]
SHOW STATUS LIKE 'Rpl_semi_sync_master_no_tx';
Variable_name Value
Rpl_semi_sync_master_no_tx 0
SHOW STATUS LIKE 'Rpl_semi_sync_master_yes_tx';
Variable_name Value
Rpl_semi_sync_master_yes_tx 0
connection master;
show master logs;
Log_name master-bin.000001
File_size #
show variables like 'rpl_semi_sync_master_enabled';
Variable_name Value
rpl_semi_sync_master_enabled ON
[ disable semi-sync on the fly ]
set global rpl_semi_sync_master_enabled=0;
show variables like 'rpl_semi_sync_master_enabled';
Variable_name Value
rpl_semi_sync_master_enabled OFF
show status like 'Rpl_semi_sync_master_status';
Variable_name Value
Rpl_semi_sync_master_status OFF
[ enable semi-sync on the fly ]
set global rpl_semi_sync_master_enabled=1;
show variables like 'rpl_semi_sync_master_enabled';
Variable_name Value
rpl_semi_sync_master_enabled ON
show status like 'Rpl_semi_sync_master_status';
Variable_name Value
Rpl_semi_sync_master_status ON
#
# Test RESET MASTER/SLAVE
#
connection slave;
include/start_slave.inc
connection master;
create table t1 (a int) engine = ENGINE_TYPE;
drop table t1;
connection slave;
[ test reset master ]
connection master;
reset master;
show status like 'Rpl_semi_sync_master_status';
Variable_name Value
Rpl_semi_sync_master_status ON
show status like 'Rpl_semi_sync_master_no_tx';
Variable_name Value
Rpl_semi_sync_master_no_tx 0
show status like 'Rpl_semi_sync_master_yes_tx';
Variable_name Value
Rpl_semi_sync_master_yes_tx 0
connection slave;
include/stop_slave.inc
reset slave;
include/kill_binlog_dump_threads.inc
connection slave;
include/start_slave.inc
connection master;
connection slave;
connection master;
create table t1 (a int) engine = ENGINE_TYPE;
insert into t1 values (1);
insert into t1 values (2), (3);
connection slave;
select * from t1;
a
1
2
3
connection master;
[ master semi-sync status should be ON ]
show status like 'Rpl_semi_sync_master_status';
Variable_name Value
Rpl_semi_sync_master_status ON
show status like 'Rpl_semi_sync_master_no_tx';
Variable_name Value
Rpl_semi_sync_master_no_tx 0
show status like 'Rpl_semi_sync_master_yes_tx';
Variable_name Value
Rpl_semi_sync_master_yes_tx 3
#
# Start semi-sync replication without SUPER privilege
#
connection slave;
include/stop_slave.inc
reset slave;
connection master;
reset master;
include/kill_binlog_dump_threads.inc
set sql_log_bin=0;
grant replication slave on *.* to rpl@127.0.0.1 identified by 'rpl_password';
flush privileges;
set sql_log_bin=1;
connection slave;
grant replication slave on *.* to rpl@127.0.0.1 identified by 'rpl_password';
flush privileges;
change master to master_user='rpl',master_password='rpl_password';
include/start_slave.inc
show status like 'Rpl_semi_sync_slave_status';
Variable_name Value
Rpl_semi_sync_slave_status ON
connection master;
connection slave;
connection master;
[ master semi-sync should be ON ]
show status like 'Rpl_semi_sync_master_clients';
Variable_name Value
Rpl_semi_sync_master_clients 1
show status like 'Rpl_semi_sync_master_status';
Variable_name Value
Rpl_semi_sync_master_status ON
show status like 'Rpl_semi_sync_master_no_tx';
Variable_name Value
Rpl_semi_sync_master_no_tx 0
show status like 'Rpl_semi_sync_master_yes_tx';
Variable_name Value
Rpl_semi_sync_master_yes_tx 0
insert into t1 values (4);
insert into t1 values (5);
[ master semi-sync should be ON ]
show status like 'Rpl_semi_sync_master_clients';
Variable_name Value
Rpl_semi_sync_master_clients 1
show status like 'Rpl_semi_sync_master_status';
Variable_name Value
Rpl_semi_sync_master_status ON
show status like 'Rpl_semi_sync_master_no_tx';
Variable_name Value
Rpl_semi_sync_master_no_tx 0
show status like 'Rpl_semi_sync_master_yes_tx';
Variable_name Value
Rpl_semi_sync_master_yes_tx 2
#
# Test semi-sync slave connect to non-semi-sync master
#
connection slave;
include/stop_slave.inc
SHOW STATUS LIKE 'Rpl_semi_sync_slave_status';
Variable_name Value
Rpl_semi_sync_slave_status OFF
connection master;
include/kill_binlog_dump_threads.inc
[ Semi-sync status on master should be ON ]
show status like 'Rpl_semi_sync_master_status';
Variable_name Value
Rpl_semi_sync_master_status ON
set global rpl_semi_sync_master_enabled= 0;
connection slave;
SHOW VARIABLES LIKE 'rpl_semi_sync_slave_enabled';
Variable_name Value
rpl_semi_sync_slave_enabled ON
include/start_slave.inc
connection master;
insert into t1 values (8);
[ master semi-sync clients should be 1, status should be OFF ]
show status like 'Rpl_semi_sync_master_clients';
Variable_name Value
Rpl_semi_sync_master_clients 1
show status like 'Rpl_semi_sync_master_status';
Variable_name Value
Rpl_semi_sync_master_status OFF
connection slave;
show status like 'Rpl_semi_sync_slave_status';
Variable_name Value
Rpl_semi_sync_slave_status ON
connection slave;
include/stop_slave.inc
connection master;
set global rpl_semi_sync_master_enabled= 0;
connection slave;
SHOW VARIABLES LIKE 'rpl_semi_sync_slave_enabled';
Variable_name Value
rpl_semi_sync_slave_enabled ON
include/start_slave.inc
connection master;
insert into t1 values (10);
connection slave;
#
# Test non-semi-sync slave connect to semi-sync master
#
connection master;
set global rpl_semi_sync_master_timeout= 5000;
set global rpl_semi_sync_master_enabled= 1;
connection slave;
include/stop_slave.inc
SHOW STATUS LIKE 'Rpl_semi_sync_slave_status';
Variable_name Value
Rpl_semi_sync_slave_status OFF
[ uninstall semi-sync slave plugin ]
set global rpl_semi_sync_slave_enabled= 0;
[ reinstall semi-sync slave plugin and disable semi-sync ]
SHOW VARIABLES LIKE 'rpl_semi_sync_slave_enabled';
Variable_name Value
rpl_semi_sync_slave_enabled OFF
SHOW STATUS LIKE 'Rpl_semi_sync_slave_status';
Variable_name Value
Rpl_semi_sync_slave_status OFF
include/start_slave.inc
SHOW STATUS LIKE 'Rpl_semi_sync_slave_status';
Variable_name Value
Rpl_semi_sync_slave_status OFF
#
# Clean up
#
connection slave;
include/stop_slave.inc
set global rpl_semi_sync_slave_enabled= 0;
connection master;
set global rpl_semi_sync_master_enabled= 0;
connection slave;
change master to master_user='root',master_password='';
include/start_slave.inc
connection master;
drop table t1;
connection slave;
connection master;
drop user rpl@127.0.0.1;
flush privileges;
set global rpl_semi_sync_master_timeout= default;
include/rpl_end.inc
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