Shulou(Shulou.com)06/01 Report--

Welcome to my "in-depth understanding of MySQL Master and Slave principle 32", as follows:

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Stack frame # 0 my_delete (name=0x7ffff0fa0490 ". / binlog.000005", MyFlags=0) at / root/softm/percona-server-5.7.22-22/mysys/my_delete.c:25#1 0x000000000186416f in inline_mysql_file_delete (key=2, src_file=0x2293340 "/ root/softm/percona-server-5.7.22-22/sql/binlog.cc", src_line=6735, name=0x7ffff0fa0490 ". / binlog.000005" Flags=0) at / root/softm/percona-server-5.7.22-22/include/mysql/psi/mysql_file.h:1331#2 0x0000000001871497 in MYSQL_BIN_LOG::purge_index_entry (this=0x2e39c40, thd=0x7fffa4000b70, decrease_log_space=0x0, need_lock_index=false) at / root/softm/percona-server-5.7.22-22/sql/binlog.cc:6735#3 0x0000000001870b35 in MYSQL_BIN_LOG::purge_logs (this=0x2e39c40, to_log=0x7ffff0fa0a80 ". / binlog.000007", included=false, need_lock_index=true Need_update_threads=true, decrease_log_space=0x0, auto_purge=false) at / root/softm/percona-server-5.7.22-22/sql/binlog.cc:6495#4 0x0000000001868839 in purge_master_logs (thd=0x7fffa4000b70, to_log=0x7fffa4006570 "binlog.000007") at / root/softm/percona-server-5.7.22-22/sql/binlog.cc:3127#5 0x00000000015b7874 in mysql_execute_command (thd=0x7fffa4000b70 First_level=true) at / root/softm/percona-server-5.7.22-22/sql/sql_parse.cc:2989#6 0x00000000015c0362 in mysql_parse (thd=0x7fffa4000b70, parser_state=0x7ffff0fa2600) at / root/softm/percona-server-5.7.22-22/sql/sql_parse.cc:5901#7 0x00000000015b3ef6 in dispatch_command (thd=0x7fffa4000b70, com_data=0x7ffff0fa2d70 Command=COM_QUERY) at / root/softm/percona-server-5.7.22-22/sql/sql_parse.cc:1490#8 0x00000000015b2c83 in do_command (thd=0x7fffa4000b70) at / root/softm/percona-server-5.7.22-22/sql/sql_parse.cc:1021#9 0x00000000016fb8fc in handle_connection (arg=0x38f2910) at / root/softm/percona-server-5.7.22-22/sql/conn_handler/connection_handler_per_thread.cc:312#10 0x0000000001932112 in pfs _ spawn_thread (arg=0x3860a50) at / root/softm/percona-server-5.7.22-22/storage/perfschema/pfs.cc:2190#11 0x00007ffff7bc6aa1 in start_thread () from / lib64/libpthread.so.0#12 0x00007ffff6719bcd in clone () from / lib64/libc.so.6 II, Approximate process

The whole deletion process is about:

First extract the binary log records that need to be deleted into a temporary index file, binlog.~rec~. Store the binary log file that you need to keep in a file called binlog.index_crash_safe. Delete the original binlog.index and rename the binlog.index_crash_safe to binlog.index.

The following is a list of files for the intermediate moment.

-rw-r- 1 root root 80 Jun 26 10:25 binlog.index-rw-r- 1 root root 32 Jun 26 10:38 binlog.~rec~-rw-r- 1 root root 48 Jun 26 10:39 binlog.index_crash_safe and then delete the binary log file from the binlog.~rec~ record. Finally, delete the binlog.~rec~ file. The whole process focuses on.

In the function MYSQL_BIN_LOG::purge_logs, we can easily see this process by setting the breakpoint on the my_delete function.

Here is a portion of my debug:

In (gdb) p purge_index_file- > file$6 = 61OS, we can see that the file descriptor is 61-> / root/softm/percona-server-5.7.22-22.

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