Code properly integrated into callers instead.
do_handle_one_connection(): no need to reset thd and thd->thread_stack
as they're not updated by cache_thread().
Part of MDEV-19515 - Improve connect speed
It was wrong anyway, as it may not get updated by the time created thread
reads it. And it was 0 for cached threads.
Part of MDEV-19515 - Improve connect speed
It may be beneficial for slow-path, where new thread is to be created.
However it is harmful for fast-path, where thread cache can fulfil
request: it caused 2 extra loads of write-contended variables.
Also shrink variables scope.
Part of MDEV-19515 - Improve connect speed
Removed FD_CLOEXEC setting: already done by mysql_socket_accept().
Moved O_NONBLOCK setting out of accepting loop.
Removed blocking acceptance attempt, which was dead code. It was supposed
to be executed before the last iteration, however it was actually executed
during the last iteration. And it is not correct to block on one socket
leaving other sockets unattended anyway.
Gives ~5% throughput improvemet in sysbench connect benchmark.
Part of MDEV-19515 - Improve connect speed
abort_loop is intended to break accepting connections loop in main thread,
however it is being used for other purposes.
cache_thread() is governed by kill_cached_threads, no need to check
abort_loop here.
Check in create_new_thread() is redundant, abort_loop already checked
by caller.
Part of MDEV-19515 - Improve connect speed
SHOW STATUS LIKE 'Open_files' was showing 18446744073709551615
my_file_opened used statistic_increment/statistic_decrement,
so one-off errors were normal and expected. But they confused
monitoring tools, so let's move my_file_opened to use atomics.
Originally introduced by e972125f1 to avoid harmless wait for
LOCK_global_system_variables in a newly created thread, which creation was
initiated by system variable update.
At the same time it opens dangerous hole, when system variable update
thread already released LOCK_global_system_variables and ack_receiver
thread haven't yet completed new THD construction. In this case THD
constructor goes completely unprotected.
Since ack_receiver.stop() waits for the thread to go down, we have to
temporarily release LOCK_global_system_variables so that it doesn't
deadlock with ack_receiver.run(). Unfortunately it breaks atomicity
of rpl_semi_sync_master_enabled updates and makes them not serialized.
LOCK_rpl_semi_sync_master_enabled was introduced to workaround the above.
TODO: move ack_receiver start/stop into repl_semisync_master
enable_master/disable_master under LOCK_binlog protection?
Part of MDEV-14984 - regression in connect performance
The MDEV-17262 commit 26432e49d3
was skipped. In Galera 4, the implementation would seem to require
changes to the streaming replication.
In the tests archive.rnd_pos main.profiling, disable_ps_protocol
for SHOW STATUS and SHOW PROFILE commands until MDEV-18974
has been fixed.
The patches features an optional shutdown behavior to hold on until
after all connected slaves have been sent the last binlogged event.
The connected slave is one whose START SLAVE has been acknowledged and
that was not stopped since that though it could be technically
reconnecting in background.
The solution therefore disallows killing the dump thread until is has
found EOF of the latest binlog file. It is up to the shutdown
requester (DBA) to set up a sufficiently large shutdown timeout value
for shudown to wait patiently until lagging behind slaves have been
synchronized. On the other hand if a specific slave needs exclusion
from synchronization the DBA would have to stop it manually which
would terminate its dump thread.
`mysqladmin shutdown' is extended with a `--wait_for_all_slaves' option
which translates to `SHUTDOW WAIT FOR ALL SLAVES' sql query
to enable the feature on the client side.
The patch also performs a small refactoring of the server shutdown
around close_connections() to introduce kill thread phases which
are two as of current.
slave_list was used to provide data for SHOW SLAVE HOSTS and
Slaves_connected status variable.
Introduced binlog_dump_thread_count which is exposed via Slaves_connected
(replaces slave_list.records).
Store Slave_info on THD and access it by iterating server_threads
(replaces slave_list).
Added:
THD::slave_info
binlog_dump_thread_count
show_slave_hosts_callback()
Removed:
slave_list
SLAVE_LIST_CHUNK
SLAVE_ERRMSG_SIZE
slave_list_key()
slave_info_free()
init_slave_list()
end_slave_list()
all_slave_list_mutexes
init_all_slave_list_mutexes()
key_LOCK_slave_list
LOCK_slave_list
Moved:
SLAVE_INFO -> Slave_info
register_slave() -> THD::register_slave()
unregister_slave() -> THD::unregister_slave()
Also removed redundant end_slave() from close_connections(): it is called
again soon afterwards by clean_up().
Pre-requisite for clean MDEV-18450 solution.
server shutdown code.
Fix fixes a race condition, if an active connection either writes,
or will be writing to the socket after it is closed.
Previous call to socket shutdown() is fully enough to wake up and idle
connection, so that close_connection is obsolete and dangerous.
