Problem
========
SQL statements close to the size of max_allowed_packet produce binary
log events larger than max_allowed_packet.
The reason why this failure is occuring is because the event length is
more than the total size of the max_allowed_packet + max_event_header
length. Now since the event length exceeds this size master Dump
thread is unable to send the packet on to the slave.
That can happen e.g with row-based replication in Update_rows event.
Fix
====
The problem was fixed by increasing the max_allowed_packet for the
slave's threads (IO/SQL) by increasing it to 1GB.
This is done using the new server option included which is used to
regulate the max_allowed_packet of the slave thread (IO/SQL).
This causes the large packets to be received by the slave and apply
it successfully.
If an error message contains '\' backslash it is displayed correctly
through show-slave-status or
query_get_value(SHOW SLAVE STATUS, Last_IO_Error, 1);. But when
SELECT REPLACE(...) is applied backslash is escaped resulting in a
different test output.
Disabled backslash escape on show_slave_status.inc and replaced '\' for
'/' using replace_regex function in order to achieve the same test
output when different path separators are used.
The server crashes when receiving a COM_BINLOG_DUMP command with a position of 0 or
larger than the file size.
The execution proceeds to an error block having the last read replication coordinates
pointer be NULL and its dereferencing crashed the server.
Fixed with making "public" previously used only for heartbeat coordinates.
post-push fixes for show_slave_io_error= 1 of wait_for_slave_io_error.inc;
Unix and win format path specifically so few tests have to change show_slave_io_error
to zero.
The bug case is similar to one fixed earlier bug_49536.
Deadlock involving LOCK_log appears to be possible because the purge running thread
is holding LOCK_log whereas there is no sense of doing that and which fact was
exploited by the earlier bug fixes.
Fixed with small reengineering of rotate_and_purge(), adding two new methods and
setting up a policy to execute those instead of the former
rotate_and_purge(RP_LOCK_LOG_IS_ALREADY_LOCKED).
The policy for using rotate(), purge() is that if the caller acquires LOCK_log itself,
it should call rotate(), release the mutex and run purge().
Side effect of this patch is refining error message of bug@11747416 to print
the whole path.
Binary log of master can get a partially logged event if the server
runs out of disk space and, while waiting for some space to be freed,
is shut down (or crashes). If the server is not stopped, it will just
wait endlessly for space to be freed, thus no partial event anomaly
occurs. The restarted master server has had a dubious policy to send
the incomplete event to slave which it apparently can't handle.
Although an error was printed out the fact of sending with unclear
error message is a source of confusion.
Actually the problem of presence an incomplete event in the binary log
was already fixed by WL 5493 (which was merged to our current trunk
branch, major version 5.6). The fix makes the server truncate the
binary log on server restart and recovery.
However 5.5 master can't do that. So the current issue is a problem of
sending incomplete events to the slave by 5.5 master.
It is fixed in this patch by changing the policy so that only complete
events are pushed by the dump thread to the IO thread. In addition,
the error text that master sends to the slave when an incomplete event
is found, now states that incomplete event may have been caused by an
out-of-disk space situation and provides coordinates of
the first and the last event bytes read.
Major replication test framework cleanup. This does the following:
- Ensure that all tests clean up the replication state when they
finish, by making check-testcase check the output of SHOW SLAVE STATUS.
This implies:
- Slave must not be running after test finished. This is good
because it removes the risk for sporadic errors in subsequent
tests when a test forgets to sync correctly.
- Slave SQL and IO errors must be cleared when test ends. This is
good because we will notice if a test gets an unexpected error in
the slave threads near the end.
- We no longer have to clean up before a test starts.
- Ensure that all tests that wait for an error in one of the slave
threads waits for a specific error. It is no longer possible to
source wait_for_slave_[sql|io]_to_stop.inc when there is an error
in one of the slave threads. This is good because:
- If a test expects an error but there is a bug that causes
another error to happen, or if it stops the slave thread without
an error, then we will notice.
- When developing tests, wait_for_*_to_[start|stop].inc will fail
immediately if there is an error in the relevant slave thread.
Before this patch, we had to wait for the timeout.
- Remove duplicated and repeated code for setting up unusual replication
topologies. Now, there is a single file that is capable of setting
up arbitrary topologies (include/rpl_init.inc, but
include/master-slave.inc is still available for the most common
topology). Tests can now end with include/rpl_end.inc, which will clean
up correctly no matter what topology is used. The topology can be
changed with include/rpl_change_topology.inc.
- Improved debug information when tests fail. This includes:
- debug info is printed on all servers configured by include/rpl_init.inc
- User can set $rpl_debug=1, which makes auxiliary replication files
print relevant debug info.
- Improved documentation for all auxiliary replication files. Now they
describe purpose, usage, parameters, and side effects.
- Many small code cleanups:
- Made have_innodb.inc output a sensible error message.
- Moved contents of rpl000017-slave.sh into rpl000017.test
- Added mysqltest variables that expose the current state of
disable_warnings/enable_warnings and friends.
- Too many to list here: see per-file comments for details.
Some of the test cases reference to binlog position and
these position numbers are written into result explicitly.
It is difficult to maintain if log event format changes.
There are a couple of cases explicit position number appears,
we handle them in different ways
A. 'CHANGE MASTER ...' with MASTER_LOG_POS or/and RELAY_LOG_POS options
Use --replace_result to mask them.
B. 'SHOW BINLOG EVENT ...'
Replaced by show_binlog_events.inc or wait_for_binlog_event.inc.
show_binlog_events.inc file's function is enhanced by given
$binlog_file and $binlog_limit.
C. 'SHOW SLAVE STATUS', 'show_slave_status.inc' and 'show_slave_status2.inc'
For the test cases just care a few items in the result of 'SHOW SLAVE STATUS',
only the items related to each test case are showed.
'show_slave_status.inc' is rebuild, only the given items in $status_items
will be showed.
'check_slave_is_running.inc' and 'check_slave_no_error.inc'
and 'check_slave_param.inc' are auxiliary files helping
to show running status and error information easily.
Problem 1: tests often fail in pushbuild with a timeout when waiting
for the slave to start/stop/receive error.
Fix 1: Updated the wait_for_slave_* macros in the following way:
- The timeout is increased by a factor ten
- Refactored the macros so that wait_for_slave_param does the work for
the other macros.
Problem 2: Tests are often incorrectly written, lacking a
source include/wait_for_slave_to_[start|stop].inc.
Fix 2: Improved the chance to get it right by adding
include/start_slave.inc and include/stop_slave.inc, and updated tests
to use these.
Problem 3: The the built-in test language command
wait_for_slave_to_stop is a misnomer (does not wait for the slave io
thread) and does not give as much debug info in case of failure as
the otherwise equivalent macro
source include/wait_for_slave_sql_to_stop.inc
Fix 3: Replaced all calls to the built-in command by a call to the
macro.
Problem 4: Some, but not all, of the wait_for_slave_* macros had an
implicit connection slave. This made some tests confusing to read,
and made it more difficult to use the macro in circular replication
scenarios, where the connection named master needs to wait.
Fix 4: Removed the implicit connection slave from all
wait_for_slave_* macros, and updated tests to use an explicit
connection slave where necessary.
Problem 5: The macros wait_slave_status.inc and wait_show_pattern.inc
were unused. Moreover, using them is difficult and error-prone.
Fix 5: remove these macros.
Problem 6: log_bin_trust_function_creators_basic failed when running
tests because it assumed @@global.log_bin_trust_function_creators=1,
and some tests modified this variable without resetting it to its
original value.
Fix 6: All tests that use this variable have been updated so that
they reset the value at end of test.
