MDEV-6150 Speed up connection speed by moving creation of THD to new thread

Creating a CONNECT object on client connect and pass this to the working thread which creates the THD.
Split LOCK_thread_count to different mutexes
Added LOCK_thread_start to syncronize threads
Moved most usage of LOCK_thread_count to dedicated functions
Use next_thread_id() instead of thread_id++

Other things:
- Thread id now starts from 1 instead of 2
- Added cast for thread_id as thread id is now of type my_thread_id
- Made THD->host const (To ensure it's not changed)
- Removed some DBUG_PRINT() about entering/exiting mutex as these was already logged by mutex code
- Fixed that aborted_connects and connection_errors_internal are counted in all cases
- Don't take locks for current_linfo when we set it (not needed as it was 0 before)

9 files changed, 153 insertions, 41 deletions

diff --git a/mysql-test/r/connect2.result b/mysql-test/r/connect2.result
new file mode 100644
index 00000000000..5e529db9376
--- /dev/null
+++ b/mysql-test/r/connect2.result
@@ -0,0 +1,45 @@
+SET @old_debug= @@session.debug;
+set @old_thread_cache_size=@@global.thread_cache_size;
+select 1;
+1
+1
+set global debug_dbug='+d,simulate_failed_connection_1';
+connect(localhost,root,,test,MASTER_PORT,MASTER_SOCKET);
+ERROR HY000: Lost connection to MySQL server at 'reading initial communication packet', system error: 95 "Operation not supported"
+set global debug_dbug=@old_debug;
+set global debug_dbug='+d,simulate_failed_connection_2';
+connect(localhost,root,,test,MASTER_PORT,MASTER_SOCKET);
+ERROR HY000: Lost connection to MySQL server at 'reading initial communication packet', system error: 95 "Operation not supported"
+set global debug_dbug=@old_debug;
+select 1;
+1
+1
+select 1;
+1
+1
+set global debug_dbug='+d,simulate_failed_connection_1';
+connect(localhost,root,,test,MASTER_PORT,MASTER_SOCKET);
+ERROR HY000: Lost connection to MySQL server at 'reading initial communication packet', system error: 95 "Operation not supported"
+set global debug_dbug=@old_debug;
+set global debug_dbug='+d,simulate_failed_connection_2';
+connect(localhost,root,,test,MASTER_PORT,MASTER_SOCKET);
+ERROR HY000: Lost connection to MySQL server at 'reading initial communication packet', system error: 95 "Operation not supported"
+set global debug_dbug=@old_debug;
+select 1;
+1
+1
+set @@global.thread_cache_size=2;
+select 1;
+1
+1
+select 1;
+1
+1
+set global debug_dbug='+d,simulate_failed_connection_2';
+connect(localhost,root,,test,MASTER_PORT,MASTER_SOCKET);
+ERROR HY000: Lost connection to MySQL server at 'reading initial communication packet', system error: 95 "Operation not supported"
+show status like "Threads_connected";
+Variable_name	Value
+Threads_connected	1
+set global debug_dbug=@old_debug;
+set global thread_cache_size=@old_thread_cache_size;
diff --git a/mysql-test/r/log_tables.result b/mysql-test/r/log_tables.result
index ff5055e1ae4..b37ea359953 100644
--- a/mysql-test/r/log_tables.result
+++ b/mysql-test/r/log_tables.result
@@ -436,9 +436,9 @@ My own slow query	sleep(2)
 My own slow query	0
 SELECT * FROM mysql.slow_log WHERE seq >= 2 LIMIT 3;
 start_time	user_host	query_time	lock_time	rows_sent	rows_examined	db	last_insert_id	insert_id	server_id	sql_text	thread_id	rows_affected	seq
-START_TIME	USER_HOST	QUERY_TIME	00:00:00.000000	1	0	test	0	0	1	SELECT "My own slow query", sleep(2)	3	0	2
-START_TIME	USER_HOST	QUERY_TIME	00:00:00.000000	1	0	test	0	0	1	SELECT "My own slow query", sleep(2)	3	0	3
-START_TIME	USER_HOST	QUERY_TIME	00:00:00.000000	1	0	test	0	0	1	SELECT "My own slow query", sleep(2)	3	0	4
+START_TIME	USER_HOST	QUERY_TIME	00:00:00.000000	1	0	test	0	0	1	SELECT "My own slow query", sleep(2)	2	0	2
+START_TIME	USER_HOST	QUERY_TIME	00:00:00.000000	1	0	test	0	0	1	SELECT "My own slow query", sleep(2)	2	0	3
+START_TIME	USER_HOST	QUERY_TIME	00:00:00.000000	1	0	test	0	0	1	SELECT "My own slow query", sleep(2)	2	0	4
 SET GLOBAL slow_query_log = 0;
 SET SESSION long_query_time =@saved_long_query_time;
 FLUSH LOGS;
diff --git a/mysql-test/r/mdev375.result b/mysql-test/r/mdev375.result
index 32580804686..426336e5939 100644
--- a/mysql-test/r/mdev375.result
+++ b/mysql-test/r/mdev375.result
@@ -10,5 +10,8 @@ ERROR HY000: Too many connections
 SELECT 0;
 0
 0
+show status like "Threads_connected";
+Variable_name	Value
+Threads_connected	3
 SET GLOBAL log_warnings=default;
 SET GLOBAL max_connections=default;
diff --git a/mysql-test/r/mysqlbinlog_row_minimal.result b/mysql-test/r/mysqlbinlog_row_minimal.result
index 6ffaeeafc53..69b5a151d41 100644
--- a/mysql-test/r/mysqlbinlog_row_minimal.result
+++ b/mysql-test/r/mysqlbinlog_row_minimal.result
@@ -27,10 +27,10 @@ ROLLBACK/*!*/;
 /*!100001 SET @@session.server_id=1*//*!*/;
 /*!100001 SET @@session.gtid_seq_no=1*//*!*/;
 # at 352
-#<date> server id 1  end_log_pos 532 	Query	thread_id=4	exec_time=x	error_code=0
+#<date> server id 1  end_log_pos 532 	Query	thread_id=3	exec_time=x	error_code=0
 use `test`/*!*/;
 SET TIMESTAMP=X/*!*/;
-SET @@session.pseudo_thread_id=4/*!*/;
+SET @@session.pseudo_thread_id=3/*!*/;
 SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=0, @@session.unique_checks=1, @@session.autocommit=1/*!*/;
 SET @@session.sql_mode=1342177280/*!*/;
 SET @@session.auto_increment_increment=1, @@session.auto_increment_offset=1/*!*/;
@@ -44,7 +44,7 @@ CREATE TABLE t1 (pk INT PRIMARY KEY, f1 INT, f2 INT, f3 TINYINT, f4 MEDIUMINT, f
 #<date> server id 1  end_log_pos 570 	GTID 0-1-2 ddl
 /*!100001 SET @@session.gtid_seq_no=2*//*!*/;
 # at 570
-#<date> server id 1  end_log_pos 743 	Query	thread_id=4	exec_time=x	error_code=0
+#<date> server id 1  end_log_pos 743 	Query	thread_id=3	exec_time=x	error_code=0
 SET TIMESTAMP=X/*!*/;
 CREATE TABLE t2 (pk INT PRIMARY KEY, f1 INT, f2 INT, f3 INT, f4 INT, f5 MEDIUMINT, f6 INT, f7 INT, f8 char(1))
 /*!*/;
@@ -69,7 +69,7 @@ BEGIN
 ###   @8=7 /* INT meta=0 nullable=1 is_null=0 */
 ###   @9='' /* STRING(1) meta=65025 nullable=1 is_null=0 */
 # at 898
-#<date> server id 1  end_log_pos 967 	Query	thread_id=4	exec_time=x	error_code=0
+#<date> server id 1  end_log_pos 967 	Query	thread_id=3	exec_time=x	error_code=0
 SET TIMESTAMP=X/*!*/;
 COMMIT
 /*!*/;
@@ -94,7 +94,7 @@ BEGIN
 ###   @8=7 /* INT meta=0 nullable=1 is_null=0 */
 ###   @9=NULL /* STRING(1) meta=65025 nullable=1 is_null=1 */
 # at 1121
-#<date> server id 1  end_log_pos 1190 	Query	thread_id=4	exec_time=x	error_code=0
+#<date> server id 1  end_log_pos 1190 	Query	thread_id=3	exec_time=x	error_code=0
 SET TIMESTAMP=X/*!*/;
 COMMIT
 /*!*/;
@@ -119,7 +119,7 @@ BEGIN
 ###   @8=7 /* INT meta=0 nullable=1 is_null=0 */
 ###   @9='A' /* STRING(1) meta=65025 nullable=1 is_null=0 */
 # at 1343
-#<date> server id 1  end_log_pos 1412 	Query	thread_id=4	exec_time=x	error_code=0
+#<date> server id 1  end_log_pos 1412 	Query	thread_id=3	exec_time=x	error_code=0
 SET TIMESTAMP=X/*!*/;
 COMMIT
 /*!*/;
@@ -144,7 +144,7 @@ BEGIN
 ###   @8=7 /* INT meta=0 nullable=1 is_null=0 */
 ###   @9='A' /* STRING(1) meta=65025 nullable=1 is_null=0 */
 # at 1568
-#<date> server id 1  end_log_pos 1637 	Query	thread_id=4	exec_time=x	error_code=0
+#<date> server id 1  end_log_pos 1637 	Query	thread_id=3	exec_time=x	error_code=0
 SET TIMESTAMP=X/*!*/;
 COMMIT
 /*!*/;
@@ -202,7 +202,7 @@ BEGIN
 ###   @8=7 /* INT meta=0 nullable=1 is_null=0 */
 ###   @9='A' /* STRING(1) meta=65025 nullable=1 is_null=0 */
 # at 1890
-#<date> server id 1  end_log_pos 1959 	Query	thread_id=4	exec_time=x	error_code=0
+#<date> server id 1  end_log_pos 1959 	Query	thread_id=3	exec_time=x	error_code=0
 SET TIMESTAMP=X/*!*/;
 COMMIT
 /*!*/;
@@ -234,7 +234,7 @@ BEGIN
 ### SET
 ###   @5=5 /* INT meta=0 nullable=1 is_null=0 */
 # at 2119
-#<date> server id 1  end_log_pos 2188 	Query	thread_id=4	exec_time=x	error_code=0
+#<date> server id 1  end_log_pos 2188 	Query	thread_id=3	exec_time=x	error_code=0
 SET TIMESTAMP=X/*!*/;
 COMMIT
 /*!*/;
@@ -260,7 +260,7 @@ BEGIN
 ### WHERE
 ###   @1=13 /* INT meta=0 nullable=0 is_null=0 */
 # at 2328
-#<date> server id 1  end_log_pos 2397 	Query	thread_id=4	exec_time=x	error_code=0
+#<date> server id 1  end_log_pos 2397 	Query	thread_id=3	exec_time=x	error_code=0
 SET TIMESTAMP=X/*!*/;
 COMMIT
 /*!*/;
@@ -286,7 +286,7 @@ BEGIN
 ### WHERE
 ###   @1=13 /* INT meta=0 nullable=0 is_null=0 */
 # at 2537
-#<date> server id 1  end_log_pos 2606 	Query	thread_id=4	exec_time=x	error_code=0
+#<date> server id 1  end_log_pos 2606 	Query	thread_id=3	exec_time=x	error_code=0
 SET TIMESTAMP=X/*!*/;
 COMMIT
 /*!*/;
diff --git a/mysql-test/suite/binlog/r/binlog_reset_master.result b/mysql-test/suite/binlog/r/binlog_reset_master.result
deleted file mode 100644
index b3d605560ff..00000000000
--- a/mysql-test/suite/binlog/r/binlog_reset_master.result
+++ /dev/null
@@ -1 +0,0 @@
-RESET MASTER;
diff --git a/mysql-test/suite/binlog/t/binlog_reset_master.test b/mysql-test/suite/binlog/t/binlog_reset_master.test
deleted file mode 100644
index 33b549ad357..00000000000
--- a/mysql-test/suite/binlog/t/binlog_reset_master.test
+++ /dev/null
@@ -1,26 +0,0 @@
-# ==== Purpose ====
-#
-# Test bugs in RESET MASTER.
-
---source include/have_debug.inc
---source include/have_log_bin.inc
-
-#######################################################################
-# BUG#12574820: binlog.binlog_tmp_table timing out in daily and weekly trunk run
-# Problem: MYSQL_BIN_LOG::reset_logs acquired LOCK_thread_count and
-# LOCK_log in the wrong order. This could cause a deadlock when
-# RESET MASTER was run concurrently with a disconnecting thread.
-#######################################################################
-
-# We use sleep, not debug_sync, because the sync point needs to be in
-# the thread shut down code after the debug sync facility has been
-# shut down.
---let $write_var= SET debug_dbug="+d,sleep_after_lock_thread_count_before_delete_thd"; CREATE TEMPORARY TABLE test.t1 (a INT);
---let $write_to_file= GENERATE
---disable_query_log
---source include/write_var_to_file.inc
---enable_query_log
-
---exec $MYSQL < $write_to_file
-RESET MASTER;
---remove_file $write_to_file
diff --git a/mysql-test/t/connect2.cnf b/mysql-test/t/connect2.cnf
new file mode 100644
index 00000000000..0acd221b871
--- /dev/null
+++ b/mysql-test/t/connect2.cnf
@@ -0,0 +1,9 @@
+!include include/default_my.cnf
+
+[mysqld.1]
+extra-port=        @ENV.MASTER_EXTRA_PORT
+extra-max-connections=2
+thread_handling=pool-of-threads
+
+[ENV]
+MASTER_EXTRA_PORT= @OPT.port
diff --git a/mysql-test/t/connect2.test b/mysql-test/t/connect2.test
new file mode 100644
index 00000000000..7427afaeffd
--- /dev/null
+++ b/mysql-test/t/connect2.test
@@ -0,0 +1,81 @@
+# This test is to check various cases of connections, some which require
+# DBUG
+
+# This test makes no sense with the embedded server
+--source include/not_embedded.inc
+--source include/have_debug.inc
+
+SET @old_debug= @@session.debug;
+set @old_thread_cache_size=@@global.thread_cache_size;
+
+# Test connections to the
+
+connect(con1,localhost,root,,test,,);
+select 1;
+disconnect con1;
+connection default;
+set global debug_dbug='+d,simulate_failed_connection_1';
+--replace_result $MASTER_MYSOCK MASTER_SOCKET $MASTER_MYPORT MASTER_PORT
+--error 2013
+connect(con1,localhost,root,,test,,);
+connection default;
+set global debug_dbug=@old_debug;
+set global debug_dbug='+d,simulate_failed_connection_2';
+--replace_result $MASTER_MYSOCK MASTER_SOCKET $MASTER_MYPORT MASTER_PORT
+--error 2013
+connect(con1,localhost,root,,test,,);
+connection default;
+set global debug_dbug=@old_debug;
+connect(con1,localhost,root,,test,,);
+select 1;
+disconnect con1;
+
+# Test connections to the extra port.
+
+connect(con1,localhost,root,,test,$MASTER_EXTRA_PORT,);
+select 1;
+disconnect con1;
+connection default;
+set global debug_dbug='+d,simulate_failed_connection_1';
+--replace_result $MASTER_MYSOCK MASTER_SOCKET $MASTER_EXTRA_PORT MASTER_PORT
+--error 2013
+connect(con1,localhost,root,,test,$MASTER_EXTRA_PORT,);
+connection default;
+set global debug_dbug=@old_debug;
+set global debug_dbug='+d,simulate_failed_connection_2';
+--replace_result $MASTER_MYSOCK MASTER_SOCKET $MASTER_EXTRA_PORT MASTER_PORT
+--error 2013
+connect(con1,localhost,root,,test,$MASTER_EXTRA_PORT,);
+connection default;
+set global debug_dbug=@old_debug;
+connect(con1,localhost,root,,test,$MASTER_EXTRA_PORT,);
+select 1;
+disconnect con1;
+connection default;
+
+#
+# Test thread cache
+#
+set @@global.thread_cache_size=2;
+connect(con1,localhost,root,,test,$MASTER_EXTRA_PORT,);
+select 1;
+connect(con2,localhost,root,,test,$MASTER_EXTRA_PORT,);
+select 1;
+disconnect con1;
+disconnect con2;
+connection default;
+set global debug_dbug='+d,simulate_failed_connection_2';
+--replace_result $MASTER_MYSOCK MASTER_SOCKET $MASTER_EXTRA_PORT MASTER_PORT
+--error 2013
+connect(con1,localhost,root,,test,$MASTER_EXTRA_PORT,);
+connection default;
+
+# Check that threads_connected didn't count aborted connections
+show status like "Threads_connected";
+
+#
+# Cleanup
+#
+
+set global debug_dbug=@old_debug;
+set global thread_cache_size=@old_thread_cache_size;
diff --git a/mysql-test/t/mdev375.test b/mysql-test/t/mdev375.test
index fe259b37808..92e403b6513 100644
--- a/mysql-test/t/mdev375.test
+++ b/mysql-test/t/mdev375.test
@@ -17,6 +17,7 @@ SELECT 2;
 
 --connection default
 SELECT 0;
+show status like "Threads_connected";
 
 SET GLOBAL log_warnings=default;
 SET GLOBAL max_connections=default;