一、影响的函数
innobase_flush_logs函数，函数如下其实注释也写得很清楚了。binlog_group_flush 参数为1。
/** Flush InnoDB redo logs to the file system.
@param[in] hton InnoDB handlerton
@param[in] binlog_group_flush true if we got invoked by binlog
group commit during flush stage, false in other cases.
@return false */staticboolinnobase_flush_logs(
handlerton* hton, bool binlog_group_flush){
DBUG_ENTER("innobase_flush_logs");
DBUG_ASSERT(hton == innodb_hton_ptr); if (srv_read_only_mode) {
DBUG_RETURN(false);
} /* If !binlog_group_flush, we got invoked by FLUSH LOGS or similar.
Else, we got invoked by binlog group commit during flush stage. */
if (binlog_group_flush && thd_flush_log_at_trx_commit(NULL) == 0) { /* innodb_flush_log_at_trx_commit=0
(write and sync once per second).
Do not flush the redo log during binlog group commit. */
DBUG_RETURN(false);
} /* Flush the redo log buffer to the redo log file.
Sync it to disc if we are in FLUSH LOGS, or if
innodb_flush_log_at_trx_commit=1
(write and sync at each commit). */
log_buffer_flush_to_disk(!binlog_group_flush
|| thd_flush_log_at_trx_commit(NULL) == 1);
DBUG_RETURN(false);
}
二、可能的组合
innodb_flush_log_at_trx_commit参数为 0
binlog_group_flush && thd_flush_log_at_trx_commit(NULL) == 0 条件成立，因此直接return了，那么这种情况下log_buffer_flush_to_disk函数不会调用，因此不会做redo刷盘。依赖master线程。
innodb_flush_log_at_trx_commit参数为 1
!binlog_group_flush|| thd_flush_log_at_trx_commit(NULL) == 1 返回为1即为True，因此调用log_buffer_flush_to_disk(True)，因此需要做redo刷盘，也要做sync。
innodb_flush_log_at_trx_commit参数为 2
!binlog_group_flush|| thd_flush_log_at_trx_commit(NULL) == 1 返回为0即为Flase，因此调用
log_buffer_flush_to_disk(Flase)，因此需要做redo刷盘，不做sync。依赖OS的刷盘机制。
三、调用栈帧
#0 innobase_flush_logs (hton=0x2e9edd0, binlog_group_flush=true) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/innobase/handler/ha_innodb.cc:4385#1 0x0000000000f65893 in flush_handlerton (thd=0x0, plugin=0x7ffff01558e8, arg=0x7ffff0155944) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/handler.cc:2606#2 0x00000000015d7716 in plugin_foreach_with_mask (thd=0x0, func=0xf65835 , type=1, state_mask=4294967287,
arg=0x7ffff0155944) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_plugin.cc:2318#3 0x0000000000f658ef in ha_flush_logs (db_type=0x0, binlog_group_flush=true) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/handler.cc:2617#4 0x000000000185733d in MYSQL_BIN_LOG::process_flush_stage_queue (this=0x2e01c80, total_bytes_var=0x7ffff0155a88, rotate_var=0x7ffff0155a87,
out_queue_var=0x7ffff0155a78) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/binlog.cc:8541#5 0x000000000185899f in MYSQL_BIN_LOG::ordered_commit (this=0x2e01c80, thd=0x7fff2c000b70, all=false, skip_commit=false)
at /root/mysql5.7.14/percona-server-5.7.14-7/sql/binlog.cc:9189#6 0x000000000185700c in MYSQL_BIN_LOG::commit (this=0x2e01c80, thd=0x7fff2c000b70, all=false) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/binlog.cc:8440#7 0x0000000000f63df8 in ha_commit_trans (thd=0x7fff2c000b70, all=false, ignore_global_read_lock=false)
at /root/mysql5.7.14/percona-server-5.7.14-7/sql/handler.cc:1818#8 0x00000000016b3e5d in trans_commit_stmt (thd=0x7fff2c000b70) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/transaction.cc:458#9 0x00000000015ac677 in mysql_execute_command (thd=0x7fff2c000b70, first_level=true) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_parse.cc:5239#10 0x00000000015adcd6 in mysql_parse (thd=0x7fff2c000b70, parser_state=0x7ffff0158600) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_parse.cc:5836#11 0x00000000015a1b95 in dispatch_command (thd=0x7fff2c000b70, com_data=0x7ffff0158d70, command=COM_QUERY)
at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_parse.cc:1447#12 0x00000000015a09c6 in do_command (thd=0x7fff2c000b70) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/sql_parse.cc:1010#13 0x00000000016e29d0 in handle_connection (arg=0x3803f30) at /root/mysql5.7.14/percona-server-5.7.14-7/sql/conn_handler/connection_handler_per_thread.cc:312#14 0x0000000001d7b4b0 in pfs_spawn_thread (arg=0x3810b80) at /root/mysql5.7.14/percona-server-5.7.14-7/storage/perfschema/pfs.cc:2188#15 0x0000003f74807aa1 in start_thread () from /lib64/libpthread.so.0#16 0x0000003f740e8bcd in clone () from /lib64/libc.so.6
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