fix for bug #17619 Scheduler race conditions

- Scheduler is either initialized at server start or never.
  Starting & stopping is now suspending & resuming.
- The scheduler has clear OO interface
- Now all calls to the scheduler are synchronous
- GLOBAL event_scheduler uses thd::sys_var_tmp (see set_var.cc)
- External API is encapsulated into class Events
- Includes fixes for all comments of Kostja's review of 19.05.2005

Starting to merge into 5.1-release (5.1.10) and push


BitKeeper/etc/ignore:
  Added libmysqld/event_scheduler.cc to the ignore list
libmysqld/Makefile.am:
  executor -> scheduler
mysql-test/r/events.result:
  update result
mysql-test/r/events_bugs.result:
  update result
mysql-test/r/events_logs_tests.result:
  update result
mysql-test/r/events_microsec.result:
  update result
mysql-test/r/events_scheduling.result:
  update result
mysql-test/r/events_stress.result:
  update result
mysql-test/t/disabled.def:
  enable these tests
mysql-test/t/events.test:
  optimize the test a bit for speed, save some seconds runtime
  remove FULL from SHOW EVENTS
  mostly use I_S.EVENTS
mysql-test/t/events_bugs.test:
  Skip irrelevant for the current design tests - all events are loaded
  on server startup. Change in mysql.event will be visible on next server start.
  Don't use numeric error codes.
mysql-test/t/events_logs_tests.test:
  optimize the test a bit for speed
mysql-test/t/events_microsec.test:
   Skip irrelevant for the current design tests - all events are loaded
      on server startup. Change in mysql.event will be visible on next server start.
      Don't use numeric error codes.
mysql-test/t/events_scheduling.test:
  broader test
mysql-test/t/events_stress.test:
  Rework the test to the new architecture of suspending/resuming.
  Use less events, no need for thousands, hundreds is still ok.
sql/Makefile.am:
  executor -> scheduler
sql/cmakelists.txt:
  executor -> scheduler
sql/event.cc:
  - remove todo comments
  - remove unneded evex_queue abstraction functions
  - move events_init() and events_shutdown() from event_executor.cc to here
  - export db_create_event
  - remove evex_load_and_compile_event, part of class Event_scheduler
  - integrate the public interface found in event.h and used by sql_parse.cc
    to use the new class Event_scheduler.
sql/event.h:
  - add COND_finished so if one thread kills a running event it waits on this
  - export callback event_timed_definer_equal, event_timed_identifier_equal(),
    event_timed_name_equal and event_timed_db_equal()
    to be used by Event_scheduler::drop_matching_events()
  - cleanup event.h
  - encapsulated all external interface into class Events
sql/event_executor.cc:
  make it empty, will delete after that
sql/event_priv.h:
  - more things in the private header
  - remove event queue abstraction functions. tightly bind to QUEUE
  - export privately db_drop_event, db_find_event, db_create_event()
  - made change_security_context() and restore_security_context() free functions
sql/event_timed.cc:
  - fix calculation of time when ENDS is set (STARTS is always set)
  - during Event_timed::compile() set the right Security_ctx. Prevents a crash
        during Event_scheduler::load_events_from_db()
  - add Event_timed::kill_thread()
  - implement event_timed_*_equal()
  - made change_security_context() and restore_security_context() free functions.
  - Comments cleanups
sql/lex.h:
  new word scheduler for SHOW SCHEDULER STATUS (available only debug builds)
sql/log.cc:
  move these from event_scheduler.cc
sql/mysql_priv.h:
  refactor kill_one_thread
  export sql_print_message_func and sql_print_message_handlers
sql/mysqld.cc:
  In close_connections, called by kill_server() skip the main scheduler
  thread and use events_shutdown() for shutting down the scheduler, in the same
  manner it's done for RPL.
  Add a new value to --event-scheduler :
  0 <- No scheduler available
  1 <- Start with scheduler enabled
  2 <- Start with scheduler suspended
sql/repl_failsafe.cc:
  refactor thd::system_thread to be an enum
sql/set_var.cc:
  move sys_var_event_executor::update() to set_var.cc
  executor -> scheduler
  use thd::sys_var_tmp
sql/set_var.h:
  executor -> scheduler
sql/share/errmsg.txt:
  3 new error messages
sql/sql_class.cc:
  refactor thd::system_thread to be an enum . more type-safety
sql/sql_class.h:
  refactor thd::system_thread to be an enum . more type-safety
sql/sql_db.cc:
  get the error from evex_drop_schema_events
sql/sql_error.h:
  export warning_level_names
sql/sql_lex.h:
  new command SHOW SCHEDULER STATUS, available only in debug build and
  for debug purposes.
sql/sql_parse.cc:
  refactor kill_one_thread() -> does the *dirty* work, and sql_kill
  just the reporting.
  add handler for SQLCOM_SHOW_SCHEDULER_STATUS
sql/sql_show.cc:
  fix verbosity handling (this will be obsoleted anyway by the fix for 17394).
sql/sql_yacc.yy:
  remove FULL from SHOW EVENTS
  add SHOW SCHEDULER STATUS in debug builds
sql/table.cc:
  Fix valgrind warning.

7 files changed, 138 insertions, 143 deletions

diff --git a/mysql-test/t/disabled.def b/mysql-test/t/disabled.def
index 7cbe4419904..e29e51b8c2c 100644
--- a/mysql-test/t/disabled.def
+++ b/mysql-test/t/disabled.def
@@ -9,10 +9,10 @@
 #  Do not use any TAB characters for whitespace.
 #
 ##############################################################################
-events_bugs              : BUG#17619 2006-02-21 andrey  Race conditions
-events_stress            : BUG#17619 2006-02-21 andrey  Race conditions
-events                   : BUG#17619 2006-02-21 andrey  Race conditions
-events_scheduling        : BUG#19170 2006-04-26 andrey  Test case of 19170 fails on some platforms. Has to be checked.
+#events_bugs              : BUG#17619 2006-02-21 andrey  Race conditions
+#events_stress            : BUG#17619 2006-02-21 andrey  Race conditions
+#events                   : BUG#17619 2006-02-21 andrey  Race conditions
+#events_scheduling        : BUG#19170 2006-04-26 andrey  Test case of 19170 fails on some platforms. Has to be checked.
 ndb_autodiscover         : BUG#18952 2006-02-16 jmiller Needs to be fixed w.r.t binlog
 ndb_autodiscover2        : BUG#18952 2006-02-16 jmiller Needs to be fixed w.r.t binlog
 ndb_binlog_discover      : BUG#19395 2006-04-28 tomas/knielsen mysqld does not always detect cluster shutdown
diff --git a/mysql-test/t/events.test b/mysql-test/t/events.test
index fbcd4924d56..819d64ccf14 100644
--- a/mysql-test/t/events.test
+++ b/mysql-test/t/events.test
@@ -15,11 +15,10 @@ CREATE EVENT e_x2 ON SCHEDULE EVERY 1 SECOND DO DROP TABLE x_table;
 connection default;
 SHOW DATABASES LIKE 'db_x';
 SET GLOBAL event_scheduler=1;
---sleep 2
+--sleep 1.5
 SHOW DATABASES LIKE 'db_x';
 SHOW TABLES FROM db_x;
-SET GLOBAL event_scheduler=0;
---sleep 1
+SET GLOBAL event_scheduler=2;
 connection priv_conn;
 DROP EVENT e_x1;
 DROP EVENT e_x2;
@@ -31,8 +30,7 @@ USE events_test;
 #
 # END:    BUG #17289 Events: missing privilege check for drop database
 #
-SET GLOBAL event_scheduler=0;
---sleep 1
+SET GLOBAL event_scheduler=2;
 drop event if exists event1;
 create event event1 on schedule every 15 minute starts now() ends date_add(now(), interval 5 hour) DO begin end;
 alter event event1 rename to event2 enable;
@@ -92,11 +90,11 @@ drop event e_43;
 --echo "Let's check whether we can use non-qualified names"
 create table non_qualif(a int);
 create event non_qualif_ev on schedule every 10 minute do insert into non_qualif values (800219);
---sleep 2
+--sleep 1
 select * from non_qualif;
 drop event non_qualif_ev;
 drop table non_qualif;
-set global event_scheduler = 0;
+set global event_scheduler = 2;
 
 create table t_event3 (a int, b float);
 drop event if exists event3;
@@ -281,15 +279,15 @@ SHOW EVENTS;
 
 --echo "This should show us only 3 events:";
 --replace_column 8 # 9 #
-SHOW FULL EVENTS;
+SHOW EVENTS;
 
 --echo "This should show us only 2 events:";
 --replace_column 8 # 9 #
-SHOW FULL EVENTS LIKE 't%event';
+SHOW EVENTS LIKE 't%event';
 
 --echo "This should show us no events:";
 --replace_column 8 # 9 #
-SHOW FULL EVENTS FROM test LIKE '%';
+SHOW EVENTS FROM test LIKE '%';
 #ok, we are back
 connection default;
 DROP DATABASE events_test2;
@@ -300,7 +298,7 @@ SHOW EVENTS;
 
 --echo "we should see 4 events now:";
 --replace_column 8 # 9 #
-SHOW FULL EVENTS;
+SHOW EVENTS;
 SELECT EVENT_CATALOG, EVENT_SCHEMA, EVENT_NAME, DEFINER, EVENT_BODY, EVENT_TYPE, EXECUTE_AT, INTERVAL_VALUE, INTERVAL_FIELD, STATUS,ON_COMPLETION, EVENT_COMMENT from information_schema.events;
 
 connection ev_con1;
@@ -330,21 +328,21 @@ create event задачка on schedule every 123 minute starts now() ends now()
 drop event задачка;
 
 # event_scheduler is a global var
---error 1229
-set event_scheduler=0;
-# event_scheduler could be only either 0 or 1
---error 1231
-set global event_scheduler=2;
+--error ER_GLOBAL_VARIABLE
+set event_scheduler=2;
+# event_scheduler could be only either 1 or 2
+--error ER_WRONG_VALUE_FOR_VAR
+set global event_scheduler=3;
 
 --echo "DISABLE the scheduler. Testing that it does not work when the variable is 0"
-set global event_scheduler=0;
+set global event_scheduler=2;
 select definer, name, db from mysql.event;
 select get_lock("test_lock1", 20);
 create event закачка on schedule every 10 hour do select get_lock("test_lock1", 20);
 --echo "Should return 1 row"
 select definer, name, db from mysql.event;
 
---echo "Should be 0 processes"
+--echo "Should be only 1 process"
 select /*1*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
 select release_lock("test_lock1");
 drop event закачка;
@@ -362,7 +360,7 @@ create event закачка on schedule every 10 hour do select get_lock("test_l
 --echo "Let some time pass to the event starts"
 --sleep 2
 --echo "Should have only 2 processes: the scheduler and the locked event"
-select /*1*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
+select /*2*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;--echo "Release the mutex, the event worker should finish."
 --echo "Release the mutex, the event worker should finish."
 select release_lock("test_lock2");
 drop event закачка;
@@ -379,18 +377,11 @@ set global event_scheduler=1;
 select get_lock("test_lock2_1", 20);
 create event закачка21 on schedule every 10 hour do select get_lock("test_lock2_1", 20);
 --sleep 1
---echo "Should see 1 process, locked on get_lock("
-#select /*3*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
---echo "Shutting down the scheduler, it should wait for the running event"
-set global event_scheduler=0;
---sleep 1
---echo "Should have only 2 processes: the scheduler and the locked event"
+--echo "Should have only 3 processes: the scheduler, our conn and the locked event"
+select /*3*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
+set global event_scheduler=2;
+--echo "Should have only our process now:"
 select /*4*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
---echo "Release the lock so the child process should finish. Hence the scheduler also"
-select release_lock("test_lock2_1");
---sleep 1
---echo "Should see 0 processes now:"
-select /*5*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
 drop event закачка21;
 
 ####
@@ -418,6 +409,7 @@ create event white_space on schedule every 10 hour disable do
 
 select 2;
 select event_schema, event_name, definer, event_body from information_schema.events where event_name='white_space';
+select event_schema, event_name, definer, event_body from information_schema.events where event_name='white_space';
 drop event white_space;
 create event white_space on schedule every 10 hour disable do	select 3;
 select event_schema, event_name, definer, event_body from information_schema.events where event_name='white_space';
@@ -426,7 +418,7 @@ drop event white_space;
 # END:  BUG #17453: Creating Event crash the server
 #
 
-##set global event_scheduler=1;
+#
 # Bug#17403 "Events: packets out of order with show create event"
 #
 create event e1 on schedule every 1 year do set @a = 5;
@@ -440,7 +432,7 @@ drop event e1;
 ##select get_lock("test_lock3", 20);
 ##create event закачка on schedule every 10 hour do select get_lock("test_lock3", 20);
 ##select sleep(2);
-##show processlist;
+##select /*5*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
 ##drop event закачка;
 ##select release_lock("test_lock3");
 
@@ -450,14 +442,14 @@ drop event e1;
 ##select get_lock("test_lock4", 20);
 ##create event закачка4 on schedule every 1 second do select get_lock("test_lock4", 20);
 ##select sleep(3);
-##--replace_column 1 # 6 #
+##select /*6*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
 ##drop event закачка4;
 ##select release_lock("test_lock4");
 
-##set global event_scheduler=0;
+##set global event_scheduler=2;
 ##select sleep(2);
 ##--replace_column 1 # 6 #
+##show processlist;
 ##select count(*) from mysql.event;
 
 drop database events_test;
-
diff --git a/mysql-test/t/events_bugs.test b/mysql-test/t/events_bugs.test
index 3f339ff0398..e3b79a6bd13 100644
--- a/mysql-test/t/events_bugs.test
+++ b/mysql-test/t/events_bugs.test
@@ -30,13 +30,13 @@ set @a=3;
 CREATE PROCEDURE p_16 () CREATE EVENT e_16 ON SCHEDULE EVERY @a SECOND DO SET @a=5;
 call p_16();
 --echo "Here we used to crash!"
---error 1516
+--error ER_EVENT_ALREADY_EXISTS
 call p_16();
---error 1516
+--error ER_EVENT_ALREADY_EXISTS
 call p_16();
 DROP EVENT e_16;
 CALL p_16();
---error 1516
+--error ER_EVENT_ALREADY_EXISTS
 CALL p_16();
 DROP PROCEDURE p_16;
 DROP EVENT e_16;
@@ -47,9 +47,9 @@ DROP EVENT e_16;
 #
 # Start - 16396: Events: Distant-future dates become past dates
 #
---error 1504
+--error ER_WRONG_VALUE
 create event e_55 on schedule at 99990101000000 do drop table t;
---error 1504
+--error ER_WRONG_VALUE
 create event e_55 on schedule every 10 hour starts 99990101000000 do drop table t;
 --error ER_EVENT_ENDS_BEFORE_STARTS
 create event e_55 on schedule every 10 minute ends 99990101000000 do drop table t;
@@ -60,7 +60,7 @@ create event e_55 on schedule every 10 minute ends 99990101000000 do drop table
 #
 # Start - 16407: Events: Changes in sql_mode won't be taken into account
 #
-set global event_scheduler=0;
+set global event_scheduler=2;
 --echo "Wait a bit to settle down"
 --sleep 1
 delete from mysql.event;
@@ -79,7 +79,7 @@ delimiter ;|
 --echo "Now if everything is fine the event has compiled and is locked
 select /*1*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
 select release_lock('test_bug16407');
-set global event_scheduler= 0;
+set global event_scheduler= 2;
 select event_schema, event_name, sql_mode from information_schema.events order by event_schema, event_name;
 --echo "Let's check whether we change the sql_mode on ALTER EVENT"
 set sql_mode='traditional';
@@ -121,9 +121,9 @@ set global event_scheduler= 1;
 --sleep 1
 select /*2*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
 select release_lock('ee_16407_2');
---sleep 3
+--sleep 2
 select /*3*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
-set global event_scheduler= 0;
+set global event_scheduler= 2;
 select * from events_smode_test order by ev_name, a;
 --echo "OK, last check before we drop them"
 select event_schema, event_name, sql_mode from information_schema.events order by event_schema, event_name;
@@ -156,7 +156,7 @@ set global event_scheduler= 1;
 --echo "Should have 2 locked processes"
 select /*4*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
 select release_lock('ee_16407_5');
---sleep 3
+--sleep 2
 --echo "Should have 0 processes locked"
 select /*5*/ user, host, db, command, state, info from information_schema.processlist where info is null or info not like '%processlist%' order by info;
 select * from events_smode_test order by ev_name, a;
@@ -166,7 +166,7 @@ drop event ee_16407_5;
 drop event ee_16407_6;
 drop procedure ee_16407_5_pendant;
 drop procedure ee_16407_6_pendant;
-set global event_scheduler= 0;
+set global event_scheduler= 2;
 drop table events_smode_test;
 set sql_mode=@old_sql_mode;
 #
diff --git a/mysql-test/t/events_logs_tests.test b/mysql-test/t/events_logs_tests.test
index 21adc17d5b8..a468685ddc6 100644
--- a/mysql-test/t/events_logs_tests.test
+++ b/mysql-test/t/events_logs_tests.test
@@ -10,7 +10,7 @@ BEGIN
 END|
 delimiter ;|
 --echo "Check General Query Log"
-SET GLOBAL event_scheduler=0;
+SET GLOBAL event_scheduler=2;
 create event log_general on schedule every 1 minute do SELect 'alabala', sleep(3) from dual;
 TRUNCATE mysql.general_log;
 --echo "1 row, the current statement!"
@@ -22,7 +22,7 @@ SET GLOBAL event_scheduler=1;
 call select_general_log();
 DROP PROCEDURE select_general_log;
 DROP EVENT log_general;
-SET GLOBAL event_scheduler=0;
+SET GLOBAL event_scheduler=2;
 --sleep 1
 
 --echo "Check slow query log"
@@ -53,10 +53,10 @@ TRUNCATE mysql.slow_log;
 SELECT user_host, query_time, db, sql_text FROM mysql.slow_log;
 --echo "Set new values"
 SET GLOBAL long_query_time=4;
-SET SESSION long_query_time=2;
+SET SESSION long_query_time=1;
 --echo "Check that logging is working"
-SELECT SLEEP(3);
---replace_regex /00:00:0[3-5]/SLEEPVAL/
+SELECT SLEEP(2);
+--replace_regex /00:00:0[2-4]/SLEEPVAL/
 SELECT user_host, query_time, db, sql_text FROM mysql.slow_log;
 TRUNCATE mysql.slow_log;
 CREATE TABLE slow_event_test (slo_val tinyint, val tinyint);
@@ -73,14 +73,15 @@ SELECT * FROM slow_event_test;
 SELECT user_host, query_time, db, sql_text FROM mysql.slow_log;
 --echo "This should go to the slow log"
 SET SESSION long_query_time=10;
+SET GLOBAL long_query_time=1;
 DROP EVENT long_event;
-CREATE EVENT long_event2 ON SCHEDULE EVERY 1 MINUTE DO INSERT INTO slow_event_test SELECT @@long_query_time, SLEEP(5);
+CREATE EVENT long_event2 ON SCHEDULE EVERY 1 MINUTE DO INSERT INTO slow_event_test SELECT @@long_query_time, SLEEP(2);
 --echo "Sleep some more time than the actual event run will take"
---sleep 7
+--sleep 3
 --echo "Check our table. Should see 2 rows"
 SELECT * FROM slow_event_test;
---echo "Check slow log. Should see 1 row because 5 is over the threshold of 4 for GLOBAL, though under SESSION which is 10"
---replace_regex /00:00:0[5-7]/SLEEPVAL/
+--echo "Check slow log. Should see 1 row because 4 is over the threshold of 3 for GLOBAL, though under SESSION which is 10"
+--replace_regex /00:00:0[2-4]/SLEEPVAL/
 SELECT user_host, query_time, db, sql_text FROM mysql.slow_log;
 DROP EVENT long_event2;
 SET GLOBAL  long_query_time =@old_global_long_query_time;
diff --git a/mysql-test/t/events_microsec.test b/mysql-test/t/events_microsec.test
index 34855fdadff..e01120a0756 100644
--- a/mysql-test/t/events_microsec.test
+++ b/mysql-test/t/events_microsec.test
@@ -1,55 +1,15 @@
 create database if not exists events_test;
 use events_test;
 
---error 1235
+--error ER_NOT_SUPPORTED_YET
 CREATE EVENT micro_test ON SCHEDULE EVERY 100 MICROSECOND DO SELECT 1;
---error 1235
+--error ER_NOT_SUPPORTED_YET
 CREATE EVENT micro_test ON SCHEDULE EVERY 100 DAY_MICROSECOND DO SELECT 1;
---error 1235
+--error ER_NOT_SUPPORTED_YET
 CREATE EVENT micro_test ON SCHEDULE EVERY 100 HOUR_MICROSECOND DO SELECT 1;
---error 1235
+--error ER_NOT_SUPPORTED_YET
 CREATE EVENT micro_test ON SCHEDULE EVERY 100 MINUTE_MICROSECOND DO SELECT 1;
---error 1235
+--error ER_NOT_SUPPORTED_YET
 CREATE EVENT micro_test ON SCHEDULE EVERY 100 SECOND_MICROSECOND DO SELECT 1;
 
---echo "Now create normal event and change it on SQL level"
-CREATE EVENT micro_test2 ON SCHEDULE EVERY 1 MONTH DO SELECT 1;
-UPDATE mysql.event SET interval_field='MICROSECOND' WHERE db=database() AND definer=user() AND name='micro_test2';
---error 1235
-SHOW CREATE EVENT micro_test2;
-SET GLOBAL event_scheduler=0;
---sleep 1
---echo "Should not be running:"
-SHOW VARIABLES like 'event_scheduler';
-UPDATE mysql.event SET interval_field='DAY_MICROSECOND' WHERE db=database() AND definer=user() AND name='micro_test2';
---error 1235
-SHOW CREATE EVENT micro_test2;
-SET GLOBAL event_scheduler=0;
---sleep 1
---echo "Should not be running:"
-SHOW VARIABLES like 'event_scheduler';
-UPDATE mysql.event SET interval_field='SECOND_MICROSECOND' WHERE db=database() AND definer=user() AND name='micro_test2';
---error 1235
-SHOW CREATE EVENT micro_test2;
-SET GLOBAL event_scheduler=0;
---sleep 1
---echo "Should not be running:"
-SHOW VARIABLES like 'event_scheduler';
-UPDATE mysql.event SET interval_field='HOUR_MICROSECOND' WHERE db=database() AND definer=user() AND name='micro_test2';
---error 1235
-SHOW CREATE EVENT micro_test2;
-SET GLOBAL event_scheduler=0;
---sleep 1
---echo "Should not be running:"
-SHOW VARIABLES like 'event_scheduler';
-UPDATE mysql.event SET interval_field='MINUTE_MICROSECOND' WHERE db=database() AND definer=user() AND name='micro_test2';
---error 1235
-SHOW CREATE EVENT micro_test2;
-SET GLOBAL event_scheduler=0;
---sleep 1
---echo "Should not be running:"
-SHOW VARIABLES like 'event_scheduler';
-SELECT COUNT(*) FROM INFORMATION_SCHEMA.PROCESSLIST WHERE USER='event_scheduler';
-DROP EVENT micro_test2;
-
 drop database events_test;
diff --git a/mysql-test/t/events_scheduling.test b/mysql-test/t/events_scheduling.test
index ae3cc7d5fac..a73d25cd8ee 100644
--- a/mysql-test/t/events_scheduling.test
+++ b/mysql-test/t/events_scheduling.test
@@ -15,7 +15,7 @@ CREATE EVENT start_n_end
   DO INSERT INTO table_2 VALUES(1);
 --sleep 5
 CREATE EVENT only_one_time ON SCHEDULE EVERY 2 SECOND ENDS NOW() + INTERVAL 1 SECOND DO INSERT INTO table_3 VALUES(1);
-CREATE EVENT two_time ON SCHEDULE EVERY 1 SECOND ENDS NOW() + INTERVAL 1 SECOND DO INSERT INTO table_4 VALUES(1);
+CREATE EVENT two_time ON SCHEDULE EVERY 1 SECOND ENDS NOW() + INTERVAL 1 SECOND ON COMPLETION PRESERVE DO INSERT INTO table_4 VALUES(1);
 --sleep 5
 SELECT IF(SUM(a) >= 4, 'OK', 'ERROR') FROM table_1;
 SELECT IF(SUM(a) >= 5, 'OK', 'ERROR') FROM table_2;
@@ -28,8 +28,8 @@ DROP EVENT start_n_end;
 --echo "Already dropped because ended. Therefore an error."
 --error ER_EVENT_DOES_NOT_EXIST
 DROP EVENT only_one_time;
---echo "Already dropped because ended. Therefore an error."
---error ER_EVENT_DOES_NOT_EXIST
+--echo "Should be preserved"
+SELECT EVENT_NAME, STATUS FROM INFORMATION_SCHEMA.EVENTS;
 DROP EVENT two_time;
 DROP TABLE table_1;
 DROP TABLE table_2;
diff --git a/mysql-test/t/events_stress.test b/mysql-test/t/events_stress.test
index f6eed79425c..24bb5bc89b1 100644
--- a/mysql-test/t/events_stress.test
+++ b/mysql-test/t/events_stress.test
@@ -2,78 +2,120 @@ CREATE DATABASE IF NOT EXISTS events_test;
 #
 # DROP DATABASE test start (bug #16406)
 #
-CREATE DATABASE events_test2;
-USE events_test2;
+CREATE DATABASE events_conn1_test2;
+CREATE TABLE events_test.fill_it(test_name varchar(20), occur datetime);
+CREATE USER event_user2@localhost;
+CREATE DATABASE events_conn2_db;
+GRANT ALL ON *.* TO event_user2@localhost;
+CREATE USER event_user3@localhost;
+CREATE DATABASE events_conn3_db;
+GRANT ALL ON *.* TO event_user3@localhost;
+connect (conn2,localhost,event_user2,,events_conn2_db);
+--echo "In the second connection we create some events which won't be dropped till the end"
+--disable_query_log
+let $1= 100;
+while ($1)
+{
+  eval CREATE EVENT conn2_ev$1 ON SCHEDULE EVERY 1 SECOND DO INSERT INTO events_test.fill_it VALUES("conn2_ev$1", NOW());
+  dec $1;
+}
+--enable_query_log
+connect (conn3,localhost,event_user3,,events_conn3_db);
+--echo "In the second connection we create some events which won't be dropped till the end"
+--disable_query_log
+let $1= 100;
+while ($1)
+{
+  eval CREATE EVENT conn3_ev$1 ON SCHEDULE EVERY 1 SECOND DO INSERT INTO events_test.fill_it VALUES("conn3_ev$1", NOW());
+  dec $1;
+}
+--enable_query_log
+connection default;
+USE events_conn1_test2;
 CREATE EVENT ev_drop1 ON SCHEDULE EVERY 10 MINUTE DISABLE DO SELECT 1;
 CREATE EVENT ev_drop2 ON SCHEDULE EVERY 10 MINUTE DISABLE DO SELECT 1;
 CREATE EVENT ev_drop3 ON SCHEDULE EVERY 10 MINUTE DISABLE DO SELECT 1;
 USE events_test;
-SELECT COUNT(*) FROM INFORMATION_SCHEMA.EVENTS WHERE EVENT_SCHEMA='events_test2';
-DROP DATABASE events_test2;
-SELECT COUNT(*) FROM INFORMATION_SCHEMA.EVENTS WHERE EVENT_SCHEMA='events_test2';
+SELECT COUNT(*) FROM INFORMATION_SCHEMA.EVENTS;
+SELECT COUNT(*) FROM INFORMATION_SCHEMA.EVENTS WHERE EVENT_SCHEMA='events_conn1_test2';
+DROP DATABASE events_conn1_test2;
+SELECT COUNT(*) FROM INFORMATION_SCHEMA.EVENTS WHERE EVENT_SCHEMA='events_conn1_test2';
 
 --echo "Now testing stability - dropping db -> events while they are running"
-CREATE DATABASE events_test2;
-USE events_test2;
+CREATE DATABASE events_conn1_test2;
+USE events_conn1_test2;
 --disable_query_log
-let $1= 1000;
+let $1= 100;
 while ($1)
 {
-  eval CREATE EVENT ev_drop$1 ON SCHEDULE EVERY 1 SECOND DO SELECT $1;
+  eval CREATE EVENT conn1_round1_ev$1 ON SCHEDULE EVERY 1 SECOND DO INSERT INTO events_test.fill_it VALUES("conn1_round1_ev$1", NOW());
   dec $1;
 }
 --enable_query_log
-SELECT COUNT(*) FROM INFORMATION_SCHEMA.EVENTS WHERE EVENT_SCHEMA='events_test2';
+SELECT COUNT(*) FROM INFORMATION_SCHEMA.EVENTS WHERE EVENT_SCHEMA='events_conn1_test2';
 SET GLOBAL event_scheduler=1;
---sleep 4
-DROP DATABASE events_test2;
+--sleep 6
+DROP DATABASE events_conn1_test2;
 
-SET GLOBAL event_scheduler=0;
---sleep 2
-SELECT COUNT(*) FROM INFORMATION_SCHEMA.EVENTS WHERE EVENT_SCHEMA='events_test2';
-CREATE DATABASE events_test3;
-USE events_test3;
+SET GLOBAL event_scheduler=2;
+SELECT COUNT(*) FROM INFORMATION_SCHEMA.EVENTS WHERE EVENT_SCHEMA='events_conn1_test2';
+CREATE DATABASE events_conn1_test3;
+USE events_conn1_test3;
 --disable_query_log
-let $1= 950;
+let $1= 100;
 while ($1)
 {
-  eval CREATE EVENT ev_drop$1 ON SCHEDULE EVERY 1 SECOND DO SELECT $1;
+  eval CREATE EVENT conn1_round2_ev$1 ON SCHEDULE EVERY 1 SECOND DO INSERT INTO events_test.fill_it VALUES("conn1_round2_ev$1", NOW());
   dec $1;
 }
 --enable_query_log
-SELECT COUNT(*) FROM INFORMATION_SCHEMA.EVENTS WHERE EVENT_SCHEMA='events_test3';
---sleep 3
-CREATE DATABASE events_test4;
-USE events_test4;
+SET GLOBAL event_scheduler=1;
+SELECT COUNT(*) FROM INFORMATION_SCHEMA.EVENTS WHERE EVENT_SCHEMA='events_conn1_test3';
+CREATE DATABASE events_conn1_test4;
+USE events_conn1_test4;
 --disable_query_log
-let $1= 860;
+let $1= 100;
 while ($1)
 {
-  eval CREATE EVENT ev_drop$1 ON SCHEDULE EVERY 1 SECOND DO SELECT $1;
+  eval CREATE EVENT conn1_round3_ev$1 ON SCHEDULE EVERY 1 SECOND DO INSERT INTO events_test.fill_it VALUES("conn1_round3_ev$1", NOW());
   dec $1;
 }
 --enable_query_log
 
-
-CREATE DATABASE events_test2;
-USE events_test2;
+CREATE DATABASE events_conn1_test2;
+USE events_conn1_test2;
 --disable_query_log
-let $1= 1050;
+let $1= 100;
 while ($1)
 {
-  eval CREATE EVENT ev_drop$1 ON SCHEDULE EVERY 1 SECOND DO SELECT $1;
+  eval CREATE EVENT ev_round4_drop$1 ON SCHEDULE EVERY 1 SECOND DO INSERT INTO events_test.fill_it VALUES("conn1_round4_ev$1", NOW());
   dec $1;
 }
 --enable_query_log
-SELECT COUNT(*) FROM INFORMATION_SCHEMA.EVENTS WHERE EVENT_SCHEMA='events_test2';
+SELECT COUNT(*) FROM INFORMATION_SCHEMA.EVENTS WHERE EVENT_SCHEMA='events_conn1_test2';
 --sleep 6
-DROP DATABASE events_test2;
-SET GLOBAL event_scheduler=0;
-DROP DATABASE events_test3;
-SET GLOBAL event_scheduler=1;
-DROP DATABASE events_test4;
+connection conn2;
+--send
+DROP DATABASE events_conn2_db;
+connection conn3;
+--send
+DROP DATABASE events_conn3_db;
+connection default;
+--send
+DROP DATABASE events_conn1_test2;
+DROP DATABASE events_conn1_test3;
+SET GLOBAL event_scheduler=2;
+DROP DATABASE events_conn1_test4;
 SET GLOBAL event_scheduler=1;
+connection conn2;
+reap;
+disconnect conn2;
+connection conn3;
+reap;
+disconnect conn3;
+connection default;
 USE events_test;
+DROP TABLE fill_it;
 #
 # DROP DATABASE test end (bug #16406)
 #