Eugene Kosov (Inactive) added a comment - 2019-01-15 15:00 Flame graph for this test: create table table_names ( id int primary key auto_increment, name varchar(255) ) engine=innodb;     insert into table_names values (1, 't1');   let $counter = 1; while ($counter <= 10000) {   let $id = `select max(id) + 1 from table_names`;   eval insert into table_names (name) values (concat('t', convert($id, char)));   inc $counter; }   let $data_size = `select count(*) from table_names`;   let $counter = 1; while ($counter <= $data_size) { let $table_name = `select name from table_names where id = $counter`;   eval create table $table_name (i int) engine=innodb;   eval insert into $table_name values (1), (2), (3), (4), (5);   inc $counter; }   let $counter = 1; while ($counter <= $data_size) { let $table_name = `select name from table_names where id = $counter`;   eval update $table_name set i = i + 1;   inc $counter; }   let $counter = 1; while ($counter <= $data_size) { let $table_name = `select name from table_names where id = $counter`;   eval drop table $table_name;   inc $counter; }     drop table table_names; It's hard to see fil in this graph. And it's hard to see the impact of a patch.

Eugene Kosov (Inactive) added a comment - 2019-01-23 09:51 Benchmark results was added to PR, so I'm requesting another round of review.

Marko Mäkelä added a comment - 2019-01-25 13:58 I did some additional research, and did not find any evidence that fsync() would not be thread-safe on any POSIX-compliant file system. Maybe we should consider using the asynchronous I/O interface in the future, that is, IOCB_CMD_FSYNC instead of fsync() or IOCB_CMD_FDSYNC instead of fdatasync() .

Eugene Kosov (Inactive) added a comment - 2019-01-25 14:21 http://pubs.opengroup.org/onlinepubs/007904975/ 2.9.1 Thread-Safety All functions defined by this volume of IEEE Std 1003.1-2001 shall be thread-safe, except that the following functions1 need not be thread-safe. Thus, fsync() shall be thread-safe by POSIX.