BUG#20676: debug warnings about too many lock waiters cause test failure.

The 250 simultaneous events all accessing the same table caused the
events_stress test to fail due to debug warnings about too many table
waiters. Fixed by using three different tables.

mysql-test/r/events_stress.result

 CREATE DATABASE IF NOT EXISTS events_test;
 CREATE DATABASE events_conn1_test2;
-CREATE TABLE events_test.fill_it(test_name varchar(20), occur datetime);
+CREATE TABLE events_test.fill_it1(test_name varchar(20), occur datetime);
+CREATE TABLE events_test.fill_it2(test_name varchar(20), occur datetime);
+CREATE TABLE events_test.fill_it3(test_name varchar(20), occur datetime);
 CREATE USER event_user2@localhost;
 CREATE DATABASE events_conn2_db;
 GRANT ALL ON *.* TO event_user2@localhost;
@@ -57,5 +59,7 @@ SET GLOBAL event_scheduler=2;
 DROP DATABASE events_conn1_test4;
 SET GLOBAL event_scheduler=1;
 USE events_test;
-DROP TABLE fill_it;
+DROP TABLE fill_it1;
+DROP TABLE fill_it2;
+DROP TABLE fill_it3;
 DROP DATABASE events_test;

mysql-test/t/events_stress.test

@@ -3,7 +3,11 @@ CREATE DATABASE IF NOT EXISTS events_test;
 # DROP DATABASE test start (bug #16406)
 #
 CREATE DATABASE events_conn1_test2;
-CREATE TABLE events_test.fill_it(test_name varchar(20), occur datetime);
+# BUG#20676: MySQL in debug mode has a limit of 100 waiters
+# (in mysys/thr_lock.c), so use three different tables to insert into.
+CREATE TABLE events_test.fill_it1(test_name varchar(20), occur datetime);
+CREATE TABLE events_test.fill_it2(test_name varchar(20), occur datetime);
+CREATE TABLE events_test.fill_it3(test_name varchar(20), occur datetime);
 CREATE USER event_user2@localhost;
 CREATE DATABASE events_conn2_db;
 GRANT ALL ON *.* TO event_user2@localhost;
@@ -16,7 +20,7 @@ connect (conn2,localhost,event_user2,,events_conn2_db);
 let $1= 50;
 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());
+  eval CREATE EVENT conn2_ev$1 ON SCHEDULE EVERY 1 SECOND DO INSERT INTO events_test.fill_it1 VALUES("conn2_ev$1", NOW());
   dec $1;
 }
 --enable_query_log
@@ -26,7 +30,7 @@ connect (conn3,localhost,event_user3,,events_conn3_db);
 let $1= 50;
 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());
+  eval CREATE EVENT conn3_ev$1 ON SCHEDULE EVERY 1 SECOND DO INSERT INTO events_test.fill_it1 VALUES("conn3_ev$1", NOW());
   dec $1;
 }
 --enable_query_log
@@ -48,7 +52,7 @@ USE events_conn1_test2;
 let $1= 50;
 while ($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());
+  eval CREATE EVENT conn1_round1_ev$1 ON SCHEDULE EVERY 1 SECOND DO INSERT INTO events_test.fill_it2 VALUES("conn1_round1_ev$1", NOW());
   dec $1;
 }
 --enable_query_log
@@ -65,7 +69,7 @@ USE events_conn1_test3;
 let $1= 50;
 while ($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());
+  eval CREATE EVENT conn1_round2_ev$1 ON SCHEDULE EVERY 1 SECOND DO INSERT INTO events_test.fill_it2 VALUES("conn1_round2_ev$1", NOW());
   dec $1;
 }
 --enable_query_log
@@ -77,7 +81,7 @@ USE events_conn1_test4;
 let $1= 50;
 while ($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());
+  eval CREATE EVENT conn1_round3_ev$1 ON SCHEDULE EVERY 1 SECOND DO INSERT INTO events_test.fill_it3 VALUES("conn1_round3_ev$1", NOW());
   dec $1;
 }
 --enable_query_log
@@ -88,7 +92,7 @@ USE events_conn1_test2;
 let $1= 50;
 while ($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());
+  eval CREATE EVENT ev_round4_drop$1 ON SCHEDULE EVERY 1 SECOND DO INSERT INTO events_test.fill_it3 VALUES("conn1_round4_ev$1", NOW());
   dec $1;
 }
 --enable_query_log
@@ -115,7 +119,9 @@ reap;
 disconnect conn3;
 connection default;
 USE events_test;
-DROP TABLE fill_it;
+DROP TABLE fill_it1;
+DROP TABLE fill_it2;
+DROP TABLE fill_it3;
 --disable_query_log
 DROP USER event_user2@localhost;
 DROP USER event_user3@localhost;