NOTE: Backporting the patch to next-mr.
The slave was crashing while failing to execute the init_slave() function.
The issue stems from two different reasons:
1 - A failure while allocating the master info structure generated a
segfault due to a NULL pointer.
2 - A failure while recovering generated a segfault due to a non-initialized
relay log file. In other words, the mi->init and rli->init were both set to true
before executing the recovery process thus creating an inconsistent state as the
relay log file was not initialized.
To circumvent such problems, we refactored the recovery process which is now executed
while initializing the relay log. It is ensured that the master info structure is
created before accessing it and any error is propagated thus avoiding to set mi->init
and rli->init to true when for instance the relay log is not initialized or the relay
info is not flushed.
The changes related to the refactory are described below:
1 - Removed call to init_recovery from init_slave.
2 - Changed the signature of the function init_recovery.
3 - Removed flushes. They are called while initializing the relay log and master
info.
4 - Made sure that if the relay info is not flushed the mi-init and rli-init are not
set to true.
In this patch, we also replaced the exit(1) in the fault injection by DBUG_ABORT()
to make it compliant with the code guidelines.
NOTE: Backporting the patch to next-mr.
The fix proposed in BUG#35542 and BUG#31665 introduces a performance issue
when fsyncing the master.info, relay.info and relay-log.bin* after #th events.
Although such solution has been proposed to reduce the probability of corrupted
files due to a slave-crash, the performance penalty introduced by it has
made the approach impractical for highly intensive workloads.
In a nutshell, the option --syn-relay-log proposed in BUG#35542 and BUG#31665
simultaneously fsyncs master.info, relay-log.info and relay-log.bin* and
this is the main source of performance issues.
This patch introduces new options that give more control to the user on
what should be fsynced and how often:
1) (--sync-master-info, integer) which syncs the master.info after #th event;
2) (--sync-relay-log, integer) which syncs the relay-log.bin* after #th
events.
3) (--sync-relay-log-info, integer) which syncs the relay.info after #th
transactions.
To provide both performance and increased reliability, we recommend the following
setup:
1) --sync-master-info = 0 eventually the operating system will fsync it;
2) --sync-relay-log = 0 eventually the operating system will fsync it;
3) --sync-relay-log-info = 1 fsyncs it after every transaction;
Notice, that the previous setup does not reduce the probability of
corrupted master.info and relay-log.bin*. To overcome the issue, this patch also
introduces a recovery mechanism that right after restart throws away relay-log.bin*
retrieved from a master and updates the master.info based on the relay.info:
4) (--relay-log-recovery, boolean) which enables a recovery mechanism that
throws away relay-log.bin* after a crash.
However, it can only recover the incorrect binlog file and position in master.info,
if other informations (host, port password, etc) are corrupted or incorrect,
then this recovery mechanism will fail to work.
BUG#31665 sync_binlog should cause relay logs to be synchronized
NOTE: Backporting the patch to next-mr.
Add sync_relay_log option to server, this option works for relay log
the same as option sync_binlog for binlog. This option also synchronize
master info to disk when set to non-zero value.
Original patches from Sinisa and Mark, with some modifications
Adding new fields Last_{IO,SQL}_Errno and Last_{IO,SQL}_Error to output
of SHOW SLAVE STATUS to hold errors from I/O and SQL thread respectively.
Old fields Last_Error and Last_Errno are aliases for Last_SQL_Error and
Last_SQL_Errno respectively.
Fields are added last to output of SHOW SLAVE STATUS to allow old applications
to use the same positional arguments into the row, while allowing new
application to benefit from the added information.
In addition, some new error codes are added (especially for the I/O
thread) to be able to provide sensible error message.
- Add MASTER_SSL_VERIFY_SERVER_CERT option to CHANGE MASTER TO
- Add Master_Ssl_Serify_Server_Cert to SHOW SLAVE STATUS
- Save and restore ssl_verify_server_cert to master info file
setting it to disabled as default.
