Description:
============
If you have a relay log index file that has ended up with
some relay log files that do not exists, then RESET SLAVE
ALL is not enough to get back to a clean state.
Analysis:
=========
In the bug scenario slave server is in stopped state and
some of the relay logs got deleted but the relay log index
file is not updated.
During slave server restart replication initialization fails
as some of the required relay logs are missing. User
executes RESET SLAVE/RESET SLAVE ALL command to start a
clean slave. As per the documentation RESET SLAVE command
clears the master info and relay log info repositories,
deletes all the relay log files, and starts a new relay log
file. But in a scenario where the slave server's
Relay_log_info object is not initialized slave will not
purge the existing relay logs. Hence the index file still
remains in a bad state. Users will not be able to start
the slave unless these files are cleared.
Fix:
===
RESET SLAVE/RESET SLAVE ALL commands should do the cleanup
even in a scenario where Relay_log_info object
initialization failed.
Backported a flag named 'error_on_rli_init_info' which is
required to identify slave's Relay_log_info object
initialization failure. This flag exists in MySQL-5.6
onwards as part of BUG#14021292 fix.
During RESET SLAVE/RESET SLAVE ALL execution this flag
indicates the Relay_log_info initialization failure.
In such a case open the relay log index/relay log files
and do the required clean up.
- Restarting mysqld with --expire-log-days=1 triggers 'log_in_use()' to be called while current_thd is NULL.
- Check current_thd before calling DEBUG_SYNC() to avoid passing NULL pointer to DEBUG_SYNC()
- Wrap debug code construct inside #ifndef DBUG_OFF like in other parts of the file
bzr merge -r4264 maria/5.5
Text conflict in sql/mysqld.cc
Text conflict in storage/xtradb/btr/btr0cur.c
Text conflict in storage/xtradb/buf/buf0buf.c
Text conflict in storage/xtradb/buf/buf0lru.c
Text conflict in storage/xtradb/handler/ha_innodb.cc
5 conflicts encountered.
~40% bugfixed(*) applied
~40$ bugfixed reverted (incorrect or we're not buggy)
~20% bugfixed applied, despite us being not buggy
(*) only changes in the server code, e.g. not cmakefiles
SHOW PROCESSLIST, SHOW BINLOGS
Problem: A deadlock was occurring when 4 threads were
involved in acquiring locks in the following way
Thread 1: Dump thread ( Slave is reconnecting, so on
Master, a new dump thread is trying kill
zombie dump threads. It acquired thread's
LOCK_thd_data and it is about to acquire
mysys_var->current_mutex ( which LOCK_log)
Thread 2: Application thread is executing show binlogs and
acquired LOCK_log and it is about to acquire
LOCK_index.
Thread 3: Application thread is executing Purge binary logs
and acquired LOCK_index and it is about to
acquire LOCK_thread_count.
Thread 4: Application thread is executing show processlist
and acquired LOCK_thread_count and it is
about to acquire zombie dump thread's
LOCK_thd_data.
Deadlock Cycle:
Thread 1 -> Thread 2 -> Thread 3-> Thread 4 ->Thread 1
The same above deadlock was observed even when thread 4 is
executing 'SELECT * FROM information_schema.processlist' command and
acquired LOCK_thread_count and it is about to acquire zombie
dump thread's LOCK_thd_data.
Analysis:
There are four locks involved in the deadlock. LOCK_log,
LOCK_thread_count, LOCK_index and LOCK_thd_data.
LOCK_log, LOCK_thread_count, LOCK_index are global mutexes
where as LOCK_thd_data is local to a thread.
We can divide these four locks in two groups.
Group 1 consists of LOCK_log and LOCK_index and the order
should be LOCK_log followed by LOCK_index.
Group 2 consists of other two mutexes
LOCK_thread_count, LOCK_thd_data and the order should
be LOCK_thread_count followed by LOCK_thd_data.
Unfortunately, there is no specific predefined lock order defined
to follow in the MySQL system when it comes to locks across these
two groups. In the above problematic example,
there is no problem in the way we are acquiring the locks
if you see each thread individually.
But If you combine all 4 threads, they end up in a deadlock.
Fix:
Since everything seems to be fine in the way threads are taking locks,
In this patch We are changing the duration of the locks in Thread 4
to break the deadlock. i.e., before the patch, Thread 4
('show processlist' command) mysqld_list_processes()
function acquires LOCK_thread_count for the complete duration
of the function and it also acquires/releases
each thread's LOCK_thd_data.
LOCK_thread_count is used to protect addition and
deletion of threads in global threads list. While show
process list is looping through all the existing threads,
it will be a problem if a thread is exited but there is no problem
if a new thread is added to the system. Hence a new mutex is
introduced "LOCK_thd_remove" which will protect deletion
of a thread from global threads list. All threads which are
getting exited should acquire LOCK_thd_remove
followed by LOCK_thread_count. (It should take LOCK_thread_count
also because other places of the code still thinks that exit thread
is protected with LOCK_thread_count. In this fix, we are changing
only 'show process list' query logic )
(Eg: unlink_thd logic will be protected with
LOCK_thd_remove).
Logic of mysqld_list_processes(or file_schema_processlist)
will now be protected with 'LOCK_thd_remove' instead of
'LOCK_thread_count'.
Now the new locking order after this patch is:
LOCK_thd_remove -> LOCK_thd_data -> LOCK_log ->
LOCK_index -> LOCK_thread_count
SHOW PROCESSLIST, SHOW BINLOGS
Problem: A deadlock was occurring when 4 threads were
involved in acquiring locks in the following way
Thread 1: Dump thread ( Slave is reconnecting, so on
Master, a new dump thread is trying kill
zombie dump threads. It acquired thread's
LOCK_thd_data and it is about to acquire
mysys_var->current_mutex ( which LOCK_log)
Thread 2: Application thread is executing show binlogs and
acquired LOCK_log and it is about to acquire
LOCK_index.
Thread 3: Application thread is executing Purge binary logs
and acquired LOCK_index and it is about to
acquire LOCK_thread_count.
Thread 4: Application thread is executing show processlist
and acquired LOCK_thread_count and it is
about to acquire zombie dump thread's
LOCK_thd_data.
Deadlock Cycle:
Thread 1 -> Thread 2 -> Thread 3-> Thread 4 ->Thread 1
The same above deadlock was observed even when thread 4 is
executing 'SELECT * FROM information_schema.processlist' command and
acquired LOCK_thread_count and it is about to acquire zombie
dump thread's LOCK_thd_data.
Analysis:
There are four locks involved in the deadlock. LOCK_log,
LOCK_thread_count, LOCK_index and LOCK_thd_data.
LOCK_log, LOCK_thread_count, LOCK_index are global mutexes
where as LOCK_thd_data is local to a thread.
We can divide these four locks in two groups.
Group 1 consists of LOCK_log and LOCK_index and the order
should be LOCK_log followed by LOCK_index.
Group 2 consists of other two mutexes
LOCK_thread_count, LOCK_thd_data and the order should
be LOCK_thread_count followed by LOCK_thd_data.
Unfortunately, there is no specific predefined lock order defined
to follow in the MySQL system when it comes to locks across these
two groups. In the above problematic example,
there is no problem in the way we are acquiring the locks
if you see each thread individually.
But If you combine all 4 threads, they end up in a deadlock.
Fix:
Since everything seems to be fine in the way threads are taking locks,
In this patch We are changing the duration of the locks in Thread 4
to break the deadlock. i.e., before the patch, Thread 4
('show processlist' command) mysqld_list_processes()
function acquires LOCK_thread_count for the complete duration
of the function and it also acquires/releases
each thread's LOCK_thd_data.
LOCK_thread_count is used to protect addition and
deletion of threads in global threads list. While show
process list is looping through all the existing threads,
it will be a problem if a thread is exited but there is no problem
if a new thread is added to the system. Hence a new mutex is
introduced "LOCK_thd_remove" which will protect deletion
of a thread from global threads list. All threads which are
getting exited should acquire LOCK_thd_remove
followed by LOCK_thread_count. (It should take LOCK_thread_count
also because other places of the code still thinks that exit thread
is protected with LOCK_thread_count. In this fix, we are changing
only 'show process list' query logic )
(Eg: unlink_thd logic will be protected with
LOCK_thd_remove).
Logic of mysqld_list_processes(or file_schema_processlist)
will now be protected with 'LOCK_thd_remove' instead of
'LOCK_thread_count'.
Now the new locking order after this patch is:
LOCK_thd_remove -> LOCK_thd_data -> LOCK_log ->
LOCK_index -> LOCK_thread_count
Problem:
When log_warnings is greater than 1, master prints binlog
dump thread information in mysqld.1.err file.
The information contains slave server id, binlog file and
binlog position. The slave server id is uint32 and the print
format was wrongly specifified (%d instead of %u).
Hence a server id which is more than 2 billion is getting
printed with a negative value.
Eg: Start binlog_dump to slave_server(-1340259414),
pos(mysql-bin.001663, 325187493)
Fix: Changed the uint32 format to %u.
Problem:
When log_warnings is greater than 1, master prints binlog
dump thread information in mysqld.1.err file.
The information contains slave server id, binlog file and
binlog position. The slave server id is uint32 and the print
format was wrongly specifified (%d instead of %u).
Hence a server id which is more than 2 billion is getting
printed with a negative value.
Eg: Start binlog_dump to slave_server(-1340259414),
pos(mysql-bin.001663, 325187493)
Fix: Changed the uint32 format to %u.
bzr merge lp:maria/5.5 -rtag:mariadb-5.5.31
Text conflict in cmake/cpack_rpm.cmake
Text conflict in debian/dist/Debian/control
Text conflict in debian/dist/Ubuntu/control
Text conflict in sql/CMakeLists.txt
Conflict adding file sql/db.opt. Moved existing file to sql/db.opt.moved.
Conflict adding file sql/db.opt.moved. Moved existing file to sql/db.opt.moved.moved.
Text conflict in sql/mysqld.cc
Text conflict in support-files/mysql.spec.sh
8 conflicts encountered.
Since event types can be >=128 and are read from a (possibly signed) char
pointer, we need to cast to unsigned char before extending to int, or we will
get an incorrect negative number. This was done in the main code path already,
but there is a rare case where we check for new events first without a lock
and then again with the lock. If the second check succeeds because a new event
turns up at just the right time, then we took a code path that was missing the
correct unsigned char cast, leading to incorrect handling of events for old
slave servers and possibly other grief.
(This was found from a sporadic failure in Buildbot of test case
rpl_mariadb_slave_capability).
NO ERRORS REPORTED
Problem:
=======
Errors from my_b_fill are ignored. MYSQL_BIN_LOG::write_cache
code assumes that 0 returned from my_b_fill always means
end-of-cache, but that is incorrect. It can result in error
and the error is ignored. Other callers of my_b_fill don't
check for error: my_b_copy_to_file, maybe my_b_gets.
Fix:
===
An error handler is already present to check the "cache"
error that is reported during "MYSQL_BIN_LOG::write_cache"
call. Hence error handlers are added for "my_b_copy_to_file"
and "my_b_gets".
During my_b_fill() function call, when the cache read fails
info->error= -1 is set. Hence a check for "info->error"
is added for the above to callers upon their return.
mysys/mf_iocache2.c:
Added a check for "cache->error" and simulation of cache read failure
mysys/my_read.c:
Simulation of read failure
sql/log_event.cc:
Added debug simulation
sql/sql_repl.cc:
Added a check for cache error
NO ERRORS REPORTED
Problem:
=======
Errors from my_b_fill are ignored. MYSQL_BIN_LOG::write_cache
code assumes that 0 returned from my_b_fill always means
end-of-cache, but that is incorrect. It can result in error
and the error is ignored. Other callers of my_b_fill don't
check for error: my_b_copy_to_file, maybe my_b_gets.
Fix:
===
An error handler is already present to check the "cache"
error that is reported during "MYSQL_BIN_LOG::write_cache"
call. Hence error handlers are added for "my_b_copy_to_file"
and "my_b_gets".
During my_b_fill() function call, when the cache read fails
info->error= -1 is set. Hence a check for "info->error"
is added for the above to callers upon their return.
In method mysql_binlog_send, right after detecting a EOF in the
read event loop, and before deciding if we should change to a new
binlog file there is a execution window where new events can be
written to the binlog and a rotation can happen. When reaching
the test, the function will then change to a new binlog file
ignoring all the events written in this window. This will result
in events not being replicated.
Only when the binlog is detected as deactivated in the event loop
of the dump thread, can we really know that no more events
remain. For this reason, this test is now made under the log lock
in the beginning of the event loop when reading the events.
In method mysql_binlog_send, right after detecting a EOF in the
read event loop, and before deciding if we should change to a new
binlog file there is a execution window where new events can be
written to the binlog and a rotation can happen. When reaching
the test, the function will then change to a new binlog file
ignoring all the events written in this window. This will result
in events not being replicated.
Only when the binlog is detected as deactivated in the event loop
of the dump thread, can we really know that no more events
remain. For this reason, this test is now made under the log lock
in the beginning of the event loop when reading the events.
FROM MYSQL_BINLOG_SEND
As part Bug #11747416 A DISK FULL MAKES BINARY LOG CORRUPT,
reading the variable "binlog_can_be_corrupted" was removed
In the existing code the value of this variable is only set,
never read. And also this issue causing compiler warnings.
So the variable is completely redundant and should be removed.
sql/sql_repl.cc:
Removing dead code
FROM MYSQL_BINLOG_SEND
As part Bug #11747416 A DISK FULL MAKES BINARY LOG CORRUPT,
reading the variable "binlog_can_be_corrupted" was removed
In the existing code the value of this variable is only set,
never read. And also this issue causing compiler warnings.
So the variable is completely redundant and should be removed.
Give error for wrong parameters to CHANGE MASTER
Extend MASTER_PASSWORD and MASTER_HOST lengths
mysql-test/suite/rpl/r/rpl_password_boundaries.result:
Test length of MASTER_PASSWORD, MASTER_HOST and MASTER_USER
mysql-test/suite/rpl/r/rpl_semi_sync.result:
Use different password than user name for better test coverage
mysql-test/suite/rpl/t/rpl_password_boundaries.test:
Test length of MASTER_PASSWORD, MASTER_HOST and MASTER_USER
mysql-test/suite/rpl/t/rpl_semi_sync.test:
Use different password than user name for better test coverage
sql/rpl_mi.h:
Extend MASTER_PASSWORD and MASTER_HOST lengths
sql/sql_repl.cc:
Give error for wrong parameters to CHANGE MASTER
sql/sql_repl.h:
Extend MASTER_PASSWORD and MASTER_HOST lengths
=== Problem ===
The test is dependent on binlog positions and checks
to see if the command 'START SLAVE' functions correctly
with the 'UNTIL' clause added to it. The 'UNTIL' clause
is added to specify that the slave should start and run
until the SQL thread reaches a given point in the master
binary log or in the slave relay log.
The test uses hard coded values for MASTER_LOG_POS and
RELAY_LOG_POS, instead of extracting it using
query_get_value() function. There is a test
'rpl.rpl_row_until' which does the similar thing but uses
query_get_value() function to set the values of
MASTER_LOG_POS/ RELAY_LOG_POS. To be precise,
rpl.rpl_row_until is a modified version of
engines/func.rpl_row_until.test.
The use of hard coded values may lead the slave to stop at a position
which may differ from the expected position in the binlog file,
an example being the failure of engines/funcs.rpl_row_until in
mysql-5.1 given as:
"query 'select * from t2' failed. Table 'test.t2' doesn't exist".
In this case, the slave actually ran a couple of extra commands
as a result of which the slave first deleted the table and then
ran a select query on table, leading to the above mentioned failure.
=== Fix ===
1) Fixed the code for failure seen in rpl.rpl_row_until.
This test was also failing although the symptoms of
failure were different.
2) Copied the contents from rpl.rpl_row_until into
into engines/funcs.rpl.rpl_row_until.
3) Updated engines/funcs.rpl_row_until.result accordingly.
mysql-test/suite/engines/funcs/r/rpl_row_until.result:
modified to accomodate the changes in corresponding
test file.
mysql-test/suite/engines/funcs/t/disabled.def:
removed from the list of disabled tests.
mysql-test/suite/engines/funcs/t/rpl_row_until.test:
fixed rpl.rpl_row_until and copied its content to
engines/funcs.rpl_row_until. The reason being both
are same tests but rpl.rpl_row_until is an
updated version.
mysql-test/suite/rpl/t/disabled.def:
removed from the list of disabled tests.
sql/sql_repl.cc:
Added a check to catch an improper combination
of arguements passed to 'START SLAVE UNTIL'. Earlier,
START SLAVE UNTIL MASTER_LOG_FILE='master-bin.000001',
MASTER_LOG_POS=561, RELAY_LOG_POS=12;
passed. It is now detected and an error is reported.
=== Problem ===
The test is dependent on binlog positions and checks
to see if the command 'START SLAVE' functions correctly
with the 'UNTIL' clause added to it. The 'UNTIL' clause
is added to specify that the slave should start and run
until the SQL thread reaches a given point in the master
binary log or in the slave relay log.
The test uses hard coded values for MASTER_LOG_POS and
RELAY_LOG_POS, instead of extracting it using
query_get_value() function. There is a test
'rpl.rpl_row_until' which does the similar thing but uses
query_get_value() function to set the values of
MASTER_LOG_POS/ RELAY_LOG_POS. To be precise,
rpl.rpl_row_until is a modified version of
engines/func.rpl_row_until.test.
The use of hard coded values may lead the slave to stop at a position
which may differ from the expected position in the binlog file,
an example being the failure of engines/funcs.rpl_row_until in
mysql-5.1 given as:
"query 'select * from t2' failed. Table 'test.t2' doesn't exist".
In this case, the slave actually ran a couple of extra commands
as a result of which the slave first deleted the table and then
ran a select query on table, leading to the above mentioned failure.
=== Fix ===
1) Fixed the code for failure seen in rpl.rpl_row_until.
This test was also failing although the symptoms of
failure were different.
2) Copied the contents from rpl.rpl_row_until into
into engines/funcs.rpl.rpl_row_until.
3) Updated engines/funcs.rpl_row_until.result accordingly.
bzr merge lp:maria/5.5
...
Text conflict in CMakeLists.txt
Text conflict in sql/mysqld.cc
Text conflict in sql/sql_class.h
Text conflict in sql/sql_truncate.cc
4 conflicts encountered.
two tests still fail:
main.innodb_icp and main.range_vs_index_merge_innodb
call records_in_range() with both range ends being open
(which triggers an assert)
