There is a server startup option --gdb a.k.a. --debug-gdb that requests
signals to be set for more convenient debugging. Most notably, SIGINT
(ctrl-c) will not be ignored, and you will be able to interrupt the
execution of the server while GDB is attached to it.
When we are debugging, the signal handlers that would normally display
a terse stack trace are useless.
When we are debugging with rr, the signal handlers may interfere with
a SIGKILL that could be sent to the process by the environment, and ruin
the rr replay trace, due to a Linux kernel bug
https://lkml.org/lkml/2021/10/31/311
To be able to diagnose bugs in kill+restart tests, we may really need
both a trace before the SIGKILL and a trace of the failure after a
subsequent server startup. So, we had better avoid hitting the problem
by simply not installing those signal handlers.
The crash happened because my_isalnum() does not support character
sets with mbminlen>1.
The value of "ft_boolean_syntax" is converted to utf8 in do_string_check().
So calling my_isalnum() is combination with "default_charset_info" was wrong.
Adding new parameters (size_t length, CHARSET_INFO *cs) to
ft_boolean_check_syntax_string() and passing self->charset(thd)
as the character set.
This patch is the plan D variant for fixing potetial mutex locking
order exercised by BF aborting and KILL command execution.
In this approach, KILL command is replicated as TOI operation.
This guarantees total isolation for the KILL command execution
in the first node: there is no concurrent replication applying
and no concurrent DDL executing. Therefore there is no risk of
BF aborting to happen in parallel with KILL command execution
either. Potential mutex deadlocks between the different mutex
access paths with KILL command execution and BF aborting cannot
therefore happen.
TOI replication is used, in this approach, purely as means
to provide isolated KILL command execution in the first node.
KILL command should not (and must not) be applied in secondary
nodes. In this patch, we make this sure by skipping KILL
execution in secondary nodes, in applying phase, where we
bail out if applier thread is trying to execute KILL command.
This is effective, but skipping the applying of KILL command
could happen much earlier as well.
This patch also fixes mutex locking order and unprotected
THD member accesses on bf aborting case. We try to hold
THD::LOCK_thd_data during bf aborting. Only case where it
is not possible is at wsrep_abort_transaction before
call wsrep_innobase_kill_one_trx where we take InnoDB
mutexes first and then THD::LOCK_thd_data.
This will also fix possible race condition during
close_connection and while wsrep is disconnecting
connections.
Added wsrep_bf_kill_debug test case
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>
because the name was misleading, it counts not threads, but THDs,
and as THD_count is the only way to increment/decrement it, it
could as well be declared inside THD_count.
before change test:
strace -fe trace=file -o /tmp/f.strace sql/mysqld --datadir=/tmp/d --log-bin=foo-bin --help --verbose && ls -la /tmp/
...
'mysqladmin variables' instead of 'mysqld --verbose --help'.
total 0
drwxrwxr-x. 2 dan dan 60 May 19 18:05 .
drwxrwxrwt. 27 root root 640 May 19 18:03 ..
-rw-rw----. 1 dan dan 0 May 19 18:05 foo-bin.index
SI_USER is, however in FreeBSD there are a couple of non-kernel
user signal infomations above SI_KERNEL.
Put a fallback just in case there is nothing available.
This patch makes the following changes around variable wsrep_on:
1) Variable wsrep_on can no longer be updated from a session that has
an active transaction running. The original behavior allowed cases
like this:
BEGIN;
INSERT INTO t1 VALUES (1);
SET SESSION wsrep_on = OFF;
INSERT INTO t1 VALUES (2);
COMMIT;
With regular transactions this would result in no replication
events (not even value 1). With streaming replication it would be
unnecessarily complex to achieve the same behavior. In the above
example, it would be possible for value 1 to be already replicated if
it happened to fill a separate fragment, while value 2 wouldn't.
2) Global variable wsrep_on no longer affects current sessions, only
subsequent ones. This is to avoid a similar case to the above, just
using just by using global wsrep_on instead session wsrep_on:
--connection conn_1
BEGIN;
INSERT INTO t1 VALUES(1);
--connection conn_2
SET GLOBAL wsrep_on = OFF;
--connection conn_1
INSERT INTO t1 VALUES(2);
COMMIT;
The above example results in the transaction to be replicated, as
global wsrep_on will only affect the session wsrep_on of new
connections.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>
wsrep_cluster_address_update() causes LOCK_wsrep_slave_threads
to be locked under LOCK_wsrep_cluster_config, while normally
the order should be the opposite.
Fix: don't protect @@wsrep_cluster_address value with the
LOCK_wsrep_cluster_config, LOCK_global_system_variables is enough.
Only protect wsrep reinitialization with the LOCK_wsrep_cluster_config.
And make it use a local copy of the global @@wsrep_cluster_address.
Also, introduce a helper function that checks whether
wsrep_cluster_address is set and also asserts that it can be safely
read by the caller.
* reuse the loop in THD::abort_current_cond_wait, don't duplicate it
* find_thread_by_id should return whatever it has found, it's the
caller's task not to kill COM_DAEMON (if the caller's a killer)
and other minor changes
One should not change the program arguments!
This change also reduces warnings from the icc compiler.
Almost all changes are just syntax changes (adding const to
'get_one_option function' declarations).
Other changes:
- Added a few cast of 'argument' from 'const char*' to 'char *'. This
was mainly in calls to 'external' functions we don't have control of.
- Ensure that all reset of 'password command line argument' are similar.
(In almost all cases it was just adding a comment and a cast)
- In mysqlbinlog.cc and mysqld.cc there was a few cases that changed
the command line argument. These places where changed to instead allocate
the option in a MEM_ROOT to avoid changing the argument. Some of this
code was changed to ensure that different programs did parsing the
same way. Added a test case for the changes in mysqlbinlog.cc
- Changed a few variables that took their value from command line options
from 'char *' to 'const char *'.
Problem is that not all plugins are loaded when wsrep_recover is executed.
Thus, we allow unknown system variables and extra system variables during
wsrep_recover. Any unknown system variables would still be caught when
the server starts up normally after the SST.
The parameter innodb_idle_flush_pct that was introduced in
MariaDB Server 10.1.2 by MDEV-6932 has no effect ever since
the InnoDB changes from MySQL 5.7.9 were applied in
commit 2e814d4702.
Let us declare the parameter as MARIADB_REMOVED_OPTION.
For earlier versions, commit ea9cd97f85
declared the parameter deprecated.
When process is aborted WSREP deinitialization and memory cleanup is not properly handled. Other reported leaks are in Galera library and should be fixed there.
