The slave SQL thread was clearing serial_rgi->thd before deleting
serial_rgi, which could cause access to NULL THD.
The clearing was introduced in commit
2e100cc5a4 and is just plain wrong. So revert
that part (single line) of that commit.
Thanks to Daniel Black for bug analysis and test case.
on disconnect THD must clean user_var_events array before
dropping temporary tables. Otherwise when binlogging a DROP,
it'll access user_var_events, but they were allocated
in the already freed memroot.
Three-way deadlock:
T1: SHOW GLOBAL STATUS
-> acquire LOCK_status
T2: STOP SLAVE
-> acquire LOCK_active_mi
-> terminate_slave_thread()
-> -> cond_timedwait for handle_slave_sql to stop
T3: sql slave thread (same applies to io thread)
-> handle_slave_sql(), when exiting
-> -> THD::add_status_to_global()
-> -> -> wait for LOCK_status...
T1: SHOW GLOBAL STATUS
-> for "Slave_heartbeat_period" status variable
-> -> show_heartbeat_period()
-> -> -> wait for LOCK_active_mi
cherry-pick from 5.6:
commit fc8b395898f40387b3468122bd0dae31e29a6fde
Author: Venkatesh Duggirala <venkatesh.duggirala@oracle.com>
Date: Wed Jun 12 21:41:05 2013 +0530
BUG#16904035-SHOW STATUS - EXCESSIVE LOCKING ON LOCK_ACTIVE_MI AND
ACTIVE_MI->RLI->DATA_LOCK
Problem: Excessive locking on lock_active_mi and rli->data_lock
while executing any `show status like 'X'` command.
Analysis: SHOW_FUNCs for Slave_running, Slave_retried_transactions,
Slave_heartbeat_period, Slave_received_heartbeats,
Slave_last_heartbeat are acquiring lock_active_mi and rli->data_lock
to show their variable value. It is ok to show stale data while showing
the status variables i.e., even if they miss one update, it will
not cause any great trouble.
Fix: Remove the locks from the above mentioned SHOW_FUNC functions.
Add a test case
There was a rare race, where a deadlock error might not be correctly
handled, causing the slave to stop with something like this in the error
log:
150423 14:04:10 [ERROR] Slave SQL: Connection was killed, Gtid 0-1-2, Internal MariaDB error code: 1927
150423 14:04:10 [Warning] Slave: Connection was killed Error_code: 1927
150423 14:04:10 [Warning] Slave: Deadlock found when trying to get lock; try restarting transaction Error_code: 1213
150423 14:04:10 [Warning] Slave: Connection was killed Error_code: 1927
150423 14:04:10 [Warning] Slave: Connection was killed Error_code: 1927
150423 14:04:10 [ERROR] Error running query, slave SQL thread aborted. Fix the problem, and restart the slave SQL thread with "SLAVE START". We stopped at log 'master-bin.000001 position 1234
The problem was incorrect error handling. When a deadlock is detected, it
causes a KILL CONNECTION on the offending thread. This error is then later
converted to a deadlock error, and the transaction is retried.
However, the deadlock error was not cleared at the start of the retry, nor
was the lingering kill signal. So it was possible to get another deadlock
kill early during retry. If this happened with particular thread
scheduling/timing, it was possible that the new KILL CONNECTION error was
masked by the earlier deadlock error, so that the second kill was not
properly converted into a deadlock error and retry.
This patch adds code that clears the old error and killed flag before
starting the retry. It also adds code to handle a deadlock kill caught in a
couple of places where it was not handled before.
This bug is a side-effect of fix for MDEV-6924, where we completely
stopped a statement-based event from getting into the binlog cache when
binary logging is not enabled (and thus, wsrep_emulate_binlog mode = 1).
As a result, the SBR events were not replicated.
Fixed by allowing the SBR events to be written into the binlog cache.
Note: Only DMLs were affected as DDLs are replicated via TOI.
Merged galera_create_trigger.test from github.com/codership/mysql-wsrep.
This was a regression from the patch for MDEV-7668.
A test was incorrect, so the slave would not properly handle re-using
temporary tables, which lead to replication failure in this case.
THD's lex->definer initially holds "*current_user" for CURRENT_USER().
As a result when wsrep tries to create the trigger query, it incorrectly
uses "*current_user". Fixed by calling get_current_user() to get the
real current user.
Merged galera_create_trigger.test from github.com/codership/mysql-wsrep.
Make sure that in parallel replication, we execute wait_for_prior_commit()
before setting table->in_use for a temporary table. Otherwise we can end up
with two parallel replication worker threads competing with each other for
use of a temporary table.
Re-factor the use of find_temporary_table() to be able to handle errors
in the caller (as wait_for_prior_commit() can return error in case of
deadlock kill).
[This commit cherry-picked to be able to merge MDEV-7936, of which it
is a pre-requisite, into both 10.0 and 10.1.]
Parallel replication depends on locking (table locks, row locks, etc.) to
prevent two conflicting transactions from running and committing in parallel.
But temporary tables are designed to be visible only to one thread, and have
no such locking.
In the concrete issue, an intermediate master could commit a CREATE TEMPORARY
TABLE in the same group commit as in INSERT into that table. Thus, a
lower-level master could attempt to run them in parallel and get an error.
More generally, we need protection from parallel replication trying to run
transactions in parallel that access a common temporary table.
This patch simply causes use of a temporary table from parallel replication
to wait for all previous transactions to commit, serialising the replication
at that point.
(A more fine-grained locking could be added later, possibly. However,
using temporary tables in statement-based replication is in any case
normally undesirable; for example a restart of the server will lose
temporary tables and can break replication).
Note that row-based replication is not affected, as it does not do any
temporary tables on the slave-side.
This patch also cleans up the locking around protecting the list of
temporary tables in Relay_log_info. This used to take the
rli->data_lock at the end of every statement, which is very bad for
concurrency. With this patch, the lock is not taken unless temporary
tables (with statement-based binlogging) are in use on the slave.
do not *always* add them to the create table definition,
but only when a sysvar value is different from a default.
also, when adding them - don't quote numbers
With changes:
* update tests to pass (new encryption/encryption_key_id syntax).
* not merged the code that makes engine aware of the encryption mode
(CRYPT_SCHEME_1_CBC, CRYPT_SCHEME_1_CTR, storing it on disk, etc),
because now the encryption plugin is handling it.
* compression+encryption did not work in either branch before the
merge - and it does not work after the merge. it might be more
broken after the merge though - some of that code was not merged.
* page checksumming code was not moved (moving of page checksumming
from fil_space_encrypt() to fil_space_decrypt was not merged).
* restored deleted lines in buf_page_get_frame(), otherwise
innodb_scrub test failed.
* no --encryption-algorithm option anymore
* encrypt/decrypt methods in the encryption plugin
* ecnrypt/decrypt methods in the encryption_km service
* file_km plugin has --file-key-management-encryption-algorithm
* debug_km always uses aes_cbc
* example_km changes between aes_cbc and aes_ecb for different key versions
Fix a race in the test case. When we do start_slave.inc immediately
followed by stop_slave.inc, it is possible to kill the IO thread while
it is still running inside get_master_version_and_clock(), and this
gives warnings in the error log that cause the test to fail.
if XA PREPARE transactions hold explicit locks.
innobase_shutdown_for_mysql(): Call trx_sys_close() before lock_sys_close()
(and dict_close()) so that trx_free_prepared() will see all locks intact.
RB: 8561
Reviewed-by: Vasil Dimov <vasil.dimov@oracle.com>
