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這篇文章給大家分享的是有關手動注冊binlog文件造成主從異常的示例分析的內容。小編覺得挺實用的，因此分享給大家做個參考，一起跟隨小編過來看看吧。
有一個朋友@水米田 問我，基于POSITION的主從。他做了如下的操作
將備份的一些binlog文件加入到了目錄中
修改index文件，加入了這些binlog文件
flush binary logs
然后整個主從環境大量延遲。
下面是另外一個朋友@徐晨亮的測試：
master上： (root:db1@xucl:10:30:22)[(none)]> show binary logs; +---------------------+-----------+| Log_name | File_size | +---------------------+-----------+ | mysql-binlog.000031 | 1019 || mysql-binlog.000032 | 424 | | mysql-binlog.000033 | 244 || mysql-binlog.000034 | 2332 | | mysql-binlog.000035 | 2134 || mysql-binlog.000036 | 845915 | | mysql-binlog.000037 | 11735 || mysql-binlog.000038 | 284 | | mysql-binlog.000039 | 284 || mysql-binlog.000040 | 284 | | mysql-binlog.000041 | 284 || mysql-binlog.000042 | 234 | +---------------------+-----------+ 12 rows in set (0.00 sec) (root:db1@xucl:10:30:34)[(none)]> purge binary logs to 'mysql-binlog.000039'; Query OK, 0 rows affected (0.00 sec) (root:db1@xucl:10:30:49)[(none)]> show binary logs; +---------------------+-----------+ | Log_name | File_size |+---------------------+-----------+| mysql-binlog.000039 | 284 | | mysql-binlog.000040 | 284 || mysql-binlog.000041 | 284 | | mysql-binlog.000042 | 234 |+---------------------+-----------+4 rows in set (0.00 sec) 執行插入數據 (root:db1@xucl:10:31:23)[xucl]> insert into t values(9,9); 將備份的binlog拷貝回原先的目錄并修改index文件進行注冊 [root@izbp12nspj47ypto9t6vyez logs]# ll總用量 884-rw-r----- 1 mysql mysql 1019 5月 20 22:03 mysql-binlog.000031-rw-r----- 1 mysql mysql 424 5月 20 22:03 mysql-binlog.000032-rw-r----- 1 mysql mysql 244 5月 20 22:03 mysql-binlog.000033-rw-r----- 1 mysql mysql 2332 5月 20 22:03 mysql-binlog.000034-rw-r----- 1 mysql mysql 2134 5月 20 22:03 mysql-binlog.000035-rw-r----- 1 mysql mysql 845915 5月 20 22:03 mysql-binlog.000036-rw-r----- 1 mysql mysql 11735 5月 20 22:05 mysql-binlog.000037-rw-r----- 1 mysql mysql 284 5月 20 22:06 mysql-binlog.000038 -rw-r----- 1 mysql mysql 284 5月 21 10:28 mysql-binlog.000039 -rw-r----- 1 mysql mysql 284 5月 21 10:28 mysql-binlog.000040-rw-r----- 1 mysql mysql 284 5月 21 10:28 mysql-binlog.000041-rw-r----- 1 mysql mysql 491 5月 21 10:31 mysql-binlog.000042-rw-r----- 1 mysql mysql 204 5月 21 10:30 mysql-binlog.index 主庫flush binary logs (root:db1@xucl:10:32:51)[(none)]> flush binary logs; Query OK, 0 rows affected (0.01 sec) (root:db1@xucl:10:32:57)[(none)]> show binary logs; +---------------------+-----------+| Log_name | File_size | +---------------------+-----------+ | mysql-binlog.000031 | 1019 || mysql-binlog.000032 | 424 | | mysql-binlog.000033 | 244 || mysql-binlog.000034 | 2332 | | mysql-binlog.000035 | 2134 || mysql-binlog.000036 | 845915 | | mysql-binlog.000037 | 11735 || mysql-binlog.000038 | 284 | | mysql-binlog.000039 | 284 || mysql-binlog.000040 | 284 | | mysql-binlog.000041 | 284 || mysql-binlog.000042 | 541 | | mysql-binlog.000043 | 234 |+---------------------+-----------+13 rows in set (0.00 sec) 此時，slave報錯如下： (root:db1@xucl:10:31:05)[(none)]> show slave status\G *************************** 1. row *************************** Slave_IO_State: Master_Host: 127.0.0.1 Master_User: repl Master_Port: 3306 Connect_Retry: 60 Master_Log_File: mysql-binlog.000035 Read_Master_Log_Pos: 194 Relay_Log_File: izbp12nspj47ypto9t6vyez-relay-bin.000011 Relay_Log_Pos: 373 Relay_Master_Log_File: mysql-binlog.000035 Slave_IO_Running: No Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 194 Relay_Log_Space: 648 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: NULLMaster_SSL_Verify_Server_Cert: No Last_IO_Errno: 1236 Last_IO_Error: Got fatal error 1236 from master when reading data from binary log: 'Cannot replicate GTID-transaction when @@GLOBAL.GTID_MODE = OFF, at file /storage/single/mysql3306/logs/mysql-binlog.000035, position 194.; the first event 'mysql-binlog.000039' at 234, the last event read from '/storage/single/mysql3306/logs/mysql-binlog.000035' at 259, the last byte read from '/storage/single/mysql33' Last_SQL_Errno: 0 Last_SQL_Error: Replicate_Ignore_Server_Ids: Master_Server_Id: 3306 Master_UUID: e8bdf01a-c79b-11e8-82b3-00163e088352 Master_Info_File: mysql.slave_master_info SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates Master_Retry_Count: 86400 Master_Bind: Last_IO_Error_Timestamp: 190521 10:32:57 Last_SQL_Error_Timestamp: Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: Executed_Gtid_Set: 4c423515-6661-11e9-b767-00163e088352:1-7, e8bdf01a-c79b-11e8-82b3-00163e088352:1-57192 Auto_Position: 0 Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version: 1 row in set (0.00 sec) 從slave上的報錯來看，在主庫flush binary logs后，從庫又讀取注冊的binlog并且又apply了
從整個測試來看，MySQL視乎將手動注冊的文件進行了傳輸和應用。報錯是因為這個庫以前是GITD_MODE=ON的，但是測試的時候已經關閉了GTID_MODE，改為了POSITION的模式，這個報錯是因為DUMP線程會進行檢測：
image.png
這個圖來自我新寫的一個系列（暫時還沒發布，大概年底才能寫好）。不管怎么說，DUMP線程已經在開始傳輸老的binlog文件了。那么原因是什么呢？下面我們將進行解釋。
flush binary logs 將包含如下操作：
獲取新的binlog文件名字
關閉舊的binlog
關閉index file
打開index file
打開新的binlog
將新的binlog加入到indexfile
具體可以參考函數MYSQL_BIN_LOG::new_file_impl。其中要說明一下獲取新的binlog文件名字是通過函數find_uniq_filename實現的，其中包含如下代碼：
file_info= dir_info->dir_entry; for (i= dir_info->number_off_files ; i-- ; file_info++)
{ if (strncmp(file_info->name, start, length) == 0 &&
is_number(file_info->name+length, &number,0))
{
set_if_bigger(max_found, number);
}
}
...
*next= (need_next || max_found == 0) ? max_found + 1 : max_found;大概意思就是掃描index file文件里面的binlog文件，獲取其序號最高的一個，然后加1。棧幀如下：
#0 find_uniq_filename (name=0x7fffec5ec6d0 "/mysqldata/mysql3340/log/binlog", next=0x7fffec5ec678, need_next=true) at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.cc:3679#1 0x000000000187d208 in generate_new_log_name (new_name=0x7fffec5ec6d0 "/mysqldata/mysql3340/log/binlog", new_ext=0x0, log_name=0x7ffedc011520 "/mysqldata/mysql3340/log/binlog", is_binlog=true) at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.cc:3767#2 0x0000000001884fdb in MYSQL_BIN_LOG::new_file_impl (this=0x2e83640, need_lock_log=false, extra_description_event=0x0) at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.cc:7175#3 0x0000000001884cbb in MYSQL_BIN_LOG::new_file_without_locking (this=0x2e83640, extra_description_event=0x0) at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.cc:7099#4 0x0000000001886b6b in MYSQL_BIN_LOG::rotate (this=0x2e83640, force_rotate=true, check_purge=0x7fffec5ecbfb) at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.cc:7775#5 0x0000000001886d53 in MYSQL_BIN_LOG::rotate_and_purge (this=0x2e83640, thd=0x7ffedc000b90, force_rotate=true) at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.cc:7846
因此即便我們手動修改了index file，flush binary logs卻不會有問題，因為它實際掃描了index file文件。
同時我們也看到flush binary logs重新加載了index file，這個時候手動修改的index file就生效了，使用show binary logs就能查看到你加入的文件了。
binlog切換后，DUMP線程也需要讀取下一個binlog文件。我們來看看它是怎么確認讀取哪一個文件的。
在函數sender.run()中可以找到循環每個binlog文件的代碼。下面一句是尋找下一個binlog文件：
int error= mysql_bin_log.find_next_log(&m_linfo, 0);
mysql_bin_log.find_next_log 包含的代碼：
my_b_seek(&index_file, linfo->index_file_offset);//進行偏移量偏移 linfo->index_file_start_offset= linfo->index_file_offset; length=my_b_gets(&index_file, fname, FN_REFLEN));//讀取文件名字... if(normalize_binlog_name(full_fname, fname, is_relay_log)) ... linfo->index_file_offset= my_b_tell(&index_file);//偏移量從新記錄以備下一次使用
我們能夠看到DUMP線程并沒有實際掃描整個index文件，而是通過一個index文件的偏移量進行讀取。如果手動修改index文件那么偏移量就出現了錯亂。因此DUMP發送的下一個文件將是不確定的。因此出現了發送手動注冊的binlog文件給從庫的現象，這種情況下可能出現下面情況：
如果是GTID_MODE 關閉，使用POSITION那么這種情況一定報錯，比如重復的行。
如果是GTID_MODE 和AUTO_POSITION=1，那么DUMP線程會進行GTID的過濾不發送，因為Event不發送所以延遲會持續一段時間為0。
如果是GTID_MODE 和AUTO_POSITION=0，那么SQL線程應用GITD_EVENT的時候會進行過濾，延遲可能出現很大的情況。
盡管GTID可能可以屏蔽這種問題，但是DUMP線程已經在考慮發送老的binlog文件了，這是不合適的。
為什么purge binary logs不會出現問題呢，因為在purge binary logs的語句下，會維護這個偏移量如下：
virtual void operator()(THD *thd)
{
LOG_INFO* linfo;
mysql_mutex_lock(&thd->LOCK_thd_data); if ((linfo= thd->current_linfo))//b binlog.cc:2829
{ /*
Index file offset can be less that purge offset only if
we just started reading the index file. In that case
we have nothing to adjust.
*/
if (linfo->index_file_offset < m_purge_offset)
linfo->fatal = (linfo->index_file_offset != 0); else
linfo->index_file_offset -= m_purge_offset;
}
mysql_mutex_unlock(&thd->LOCK_thd_data);我們可以看到linfo->index_file_offset -= m_purge_offset;這樣一個語句。下面是棧幀：
#0 Adjust_offset::operator() (this=0x7fffec5ec720, thd=0x7ffedc000be0) at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.cc:2831#1 0x0000000000eef320 in Do_THD::operator() (this=0x7fffec5ec6a0, thd=0x7ffedc000be0) at /mysqldata/percona-server-locks-detail-5.7.22/sql/mysqld_thd_manager.cc:46#2 0x0000000000eefa0f in std::for_each<THD**, Do_THD> (__first=0x3003358, __last=0x3003368, __f=...) at /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7/bits/stl_algo.h:4200#3 0x0000000000eeefc0 in Global_THD_manager::do_for_all_thd (this=0x3003340, func=0x7fffec5ec720) at /mysqldata/percona-server-locks-detail-5.7.22/sql/mysqld_thd_manager.cc:273#4 0x000000000187ae0a in adjust_linfo_offsets (purge_offset=0) at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.cc:2873#5 0x0000000001883239 in MYSQL_BIN_LOG::remove_logs_from_index (this=0x2e83640, log_info=0x7fffec5ec7d0, need_update_threads=true) at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.cc:6352#6 0x0000000001883676 in MYSQL_BIN_LOG::purge_logs (this=0x2e83640, to_log=0x7fffec5eca80 "/mysqldata/mysql3340/log/binlog.000001", included=false, need_lock_index=true, need_update_threads=true, decrease_log_space=0x0, auto_purge=false) at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.cc:6469#7 0x000000000187b4b5 in purge_master_logs (thd=0x7ffee0000c00, to_log=0x7ffee0006600 "binlog.000001") at /mysqldata/percona-server-locks-detail-5.7.22/sql/binlog.cc:3127
mysql> show binary logs; +---------------+-----------+ | Log_name | File_size | +---------------+-----------+ | binlog.000001 | 198 | | binlog.000002 | 154 | +---------------+-----------+2 rows in set (0.00 sec) mysql> show create table testcp \G; *************************** 1. row *************************** Table: testcp Create Table: CREATE TABLE `testcp` ( `id` int(11) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf81 row in set (0.00 sec) ERROR: No query specified
主庫：
mysql> insert into testcp values(20); Query OK, 1 row affected (0.43 sec) mysql> select * from testcp; +----+| id |+----+| 10 || 20 |+----+2 rows in set (0.01 sec)
從庫：
mysql> show slave status \G; *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.99.41 Master_User: repl Master_Port: 3340 Connect_Retry: 60 Master_Log_File: binlog.000002 Read_Master_Log_Pos: 417 Relay_Log_File: relay.000004 Relay_Log_Pos: 624 Relay_Master_Log_File: binlog.000002 Slave_IO_Running: Yes Slave_SQL_Running: Yes ... mysql> select * from testcp; +----+| id |+----+| 10 || 20 |+----+
這個時候DUMP線程index file偏移指針如下：
image.png
做之前拷貝原有binlog.000001為binlog.000001bak因為等會要拷貝回去
mysql> purge binary logs to 'binlog.000002'; Query OK, 0 rows affected (3.14 sec) mysql> show binary logs; +---------------+-----------+| Log_name | File_size | +---------------+-----------+ | binlog.000002 | 417 |+---------------+-----------+1 row in set (0.00 sec)
因為purge binary logs命令會維護偏移指針，這個時候DUMP線程的index file偏移指針如下：
image.png
將binlog.000001bak拷貝為binlog.000001，然后修改index file將binlog.000001加入回去，然后flush binary logs如下：
mysql> flush binary logs; Query OK, 0 rows affected (0.15 sec) mysql> show binary logs; +---------------+-----------+| Log_name | File_size | +---------------+-----------+ | binlog.000001 | 198 || binlog.000002 | 461 | +---------------+-----------+ 2 rows in set (0.00 sec)
手動完成這個工作并不會維護DUMP線程的index file偏移指針，因此如下：
image.png
就這樣DUMP線程重新發送了一次binlog.000002的內容，POSITION的從庫只能報錯了如下：
mysql> select * from replication_applier_status_by_worker \G *************************** 1. row *************************** CHANNEL_NAME: WORKER_ID: 1 THREAD_ID: NULL SERVICE_STATE: OFF LAST_SEEN_TRANSACTION: ANONYMOUS LAST_ERROR_NUMBER: 1062 LAST_ERROR_MESSAGE: Worker 1 failed executing transaction 'ANONYMOUS' at master log binlog.000002, end_log_pos 386; Could not execute Write_rows event on table testmts.testcp; Duplicate entry '20' for key 'PRIMARY', Error_code: 1062; handler error HA_ERR_FOUND_DUPP_KEY; the event's master log binlog.000002, end_log_pos 386 LAST_ERROR_TIMESTAMP: 2019-05-21 14:46:26
感謝各位的閱讀！關于“手動注冊binlog文件造成主從異常的示例分析”這篇文章就分享到這里了，希望以上內容可以對大家有一定的幫助，讓大家可以學到更多知識，如果覺得文章不錯，可以把它分享出去讓更多的人看到吧！
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