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3ab71376ce
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.
121 lines
3.8 KiB
C++
121 lines
3.8 KiB
C++
/* Copyright (C) 2000-2003 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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#ifndef RPL_MI_H
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#define RPL_MI_H
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#ifdef HAVE_REPLICATION
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#include "rpl_rli.h"
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#include "rpl_reporting.h"
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/*****************************************************************************
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Replication IO Thread
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Master_info contains:
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- information about how to connect to a master
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- current master log name
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- current master log offset
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- misc control variables
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Master_info is initialized once from the master.info file if such
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exists. Otherwise, data members corresponding to master.info fields
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are initialized with defaults specified by master-* options. The
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initialization is done through init_master_info() call.
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The format of master.info file:
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log_name
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log_pos
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master_host
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master_user
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master_pass
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master_port
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master_connect_retry
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To write out the contents of master.info file to disk ( needed every
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time we read and queue data from the master ), a call to
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flush_master_info() is required.
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To clean up, call end_master_info()
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*****************************************************************************/
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class Master_info : public Slave_reporting_capability
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{
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public:
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Master_info(bool is_slave_recovery);
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~Master_info();
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/* the variables below are needed because we can change masters on the fly */
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char master_log_name[FN_REFLEN];
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char host[HOSTNAME_LENGTH+1];
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char user[USERNAME_LENGTH+1];
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char password[MAX_PASSWORD_LENGTH+1];
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my_bool ssl; // enables use of SSL connection if true
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char ssl_ca[FN_REFLEN], ssl_capath[FN_REFLEN], ssl_cert[FN_REFLEN];
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char ssl_cipher[FN_REFLEN], ssl_key[FN_REFLEN];
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my_bool ssl_verify_server_cert;
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my_off_t master_log_pos;
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File fd; // we keep the file open, so we need to remember the file pointer
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IO_CACHE file;
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pthread_mutex_t data_lock,run_lock;
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pthread_cond_t data_cond,start_cond,stop_cond;
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THD *io_thd;
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MYSQL* mysql;
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uint32 file_id; /* for 3.23 load data infile */
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Relay_log_info rli;
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uint port;
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uint connect_retry;
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#ifndef DBUG_OFF
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int events_till_disconnect;
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#endif
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bool inited;
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volatile bool abort_slave;
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volatile uint slave_running;
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volatile ulong slave_run_id;
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/*
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The difference in seconds between the clock of the master and the clock of
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the slave (second - first). It must be signed as it may be <0 or >0.
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clock_diff_with_master is computed when the I/O thread starts; for this the
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I/O thread does a SELECT UNIX_TIMESTAMP() on the master.
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"how late the slave is compared to the master" is computed like this:
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clock_of_slave - last_timestamp_executed_by_SQL_thread - clock_diff_with_master
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*/
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long clock_diff_with_master;
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/*
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Keeps track of the number of events before fsyncing.
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The option --sync-master-info determines how many
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events should happen before fsyncing.
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*/
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uint sync_counter;
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};
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void init_master_info_with_options(Master_info* mi);
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int init_master_info(Master_info* mi, const char* master_info_fname,
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const char* slave_info_fname,
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bool abort_if_no_master_info_file,
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int thread_mask);
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void end_master_info(Master_info* mi);
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int flush_master_info(Master_info* mi, bool flush_relay_log_cache);
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#endif /* HAVE_REPLICATION */
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#endif /* RPL_MI_H */
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