Bug#23251517: SEMISYNC REPLICATION HANGING

Revert following bug fix:

Bug#20685029: SLAVE IO THREAD SHOULD STOP WHEN DISK IS
FULL
Bug#21753696: MAKE SHOW SLAVE STATUS NON BLOCKING IF IO
THREAD WAITS FOR DISK SPACE

This fix results in a deadlock between slave IO thread
and SQL thread.

(cherry picked from commit e3fea6c6dbb36c6ab21c4ab777224560e9608b53)

Author: Sujatha Sivakumar

mysql-test/include/assert_grep.inc

@@ -43,7 +43,6 @@
 #
 #    [--let $rpl_server_count= 7]
 #    --let $rpl_topology= 1->2->3->1->4, 2->5, 6->7
-#    [--let $rpl_extra_connections_per_server= 1]
 #    [--let $rpl_check_server_ids= 1]
 #    [--let $rpl_skip_change_master= 1]
 #    [--let $rpl_skip_start_slave= 1]
@@ -66,12 +65,6 @@
 #      want to specify the empty topology (no server replicates at
 #      all), you have to set $rpl_topology=none.
 #
-#    $rpl_extra_connections_per_server
-#      By default, this script creates connections server_N and
-#      server_N_1.  If you can set this variable to a number, the
-#      script creates:
-#      server_N, server_N_1, ..., server_N_$rpl_extra_connections_per_server
-#
 #    $rpl_check_server_ids
 #      If $rpl_check_server_ids is set, this script checks that the
 #      @@server_id of all servers are different. This is normally
@@ -146,17 +139,8 @@ if (!$SERVER_MYPORT_4)
 # Check that $rpl_server_count is set
 if (!$rpl_server_count)
 {
-  --let $rpl_server_count= `SELECT REPLACE('$rpl_topology', '->', ',')`
-  if (`SELECT LOCATE(',', '$rpl_server_count')`)
-  {
-    --let $rpl_server_count= `SELECT GREATEST($rpl_server_count)`
-  }
-}
-
---let $_rpl_extra_connections_per_server= $rpl_extra_connections_per_server
-if ($_rpl_extra_connections_per_server == '')
-{
-  --let $_rpl_extra_connections_per_server= 1
+  --let $_compute_rpl_server_count= `SELECT REPLACE('$rpl_topology', '->', ',')`
+  --let $rpl_server_count= `SELECT GREATEST($_compute_rpl_server_count)`
 }
 
 
@@ -175,20 +159,15 @@ if (!$rpl_debug)
 # Create two connections to each server; reset master/slave, select
 # database, set autoinc variables.
 --let $_rpl_server= $rpl_server_count
---let $underscore= _
+--let $_rpl_one= _1
 while ($_rpl_server)
 {
   # Connect.
   --let $rpl_server_number= $_rpl_server
   --let $rpl_connection_name= server_$_rpl_server
   --source include/rpl_connect.inc
-  --let $_rpl_connection_number= 1
-  while ($_rpl_connection_number <= $_rpl_extra_connections_per_server)
-  {
-    --let $rpl_connection_name= server_$_rpl_server$underscore$_rpl_connection_number
-    --source include/rpl_connect.inc
-    --inc $_rpl_connection_number
-  }
+  --let $rpl_connection_name= server_$_rpl_server$_rpl_one
+  --source include/rpl_connect.inc
 
   # Configure server.
   --let $rpl_connection_name= server_$_rpl_server

mysql-test/include/rpl_init.inc

@@ -12,7 +12,6 @@
 # ==== Usage ====
 #
 # --let $rpl_server_number= N
-# [--let $rpl_extra_connections_per_server= 1]
 # [--let $rpl_debug= 1]
 # --source include/rpl_reconnect.inc
 #
@@ -22,7 +21,7 @@
 #     master server, 2 the slave server, 3 the 3rd server, and so on.
 #     Cf. include/rpl_init.inc
 #
-#   $rpl_extra_connections_per_server, $rpl_debug
+#   $rpl_debug
 #     See include/rpl_init.inc
 
 --let $include_filename= rpl_reconnect.inc
@@ -33,11 +32,6 @@ if (!$rpl_server_number)
   --die ERROR IN TEST: you must set $rpl_server_number before you source rpl_connect.inc
 }
 
-if ($_rpl_extra_connections_per_server == '')
-{
-  --let $_rpl_extra_connections_per_server= 1
-}
-
 
 if ($rpl_debug)
 {
@@ -78,14 +72,10 @@ if (!$_rpl_server_number)
 --source include/rpl_connection.inc
 --enable_reconnect
 
---let $_rpl_connection_number= 1
-while ($_rpl_connection_number <= $_rpl_extra_connections_per_server)
-{
-  --let $rpl_connection_name= server_$rpl_server_number$underscore$_rpl_connection_number
-  --source include/rpl_connection.inc
-  --enable_reconnect
-  --inc $_rpl_connection_number
-}
+--let $_rpl_one= _1
+--let $rpl_connection_name= server_$rpl_server_number$_rpl_one
+--source include/rpl_connection.inc
+--enable_reconnect
 
 if ($rpl_debug)
 {
@@ -132,15 +122,10 @@ if (!$_rpl_server_number)
 --source include/wait_until_connected_again.inc
 --disable_reconnect
 
---let $_rpl_connection_number= 1
-while ($_rpl_connection_number <= $_rpl_extra_connections_per_server)
-{
-  --let $rpl_connection_name= server_$rpl_server_number$underscore$_rpl_connection_number
-  --source include/rpl_connection.inc
-  --source include/wait_until_connected_again.inc
-  --disable_reconnect
-  --inc $_rpl_connection_number
-}
+--let $rpl_connection_name= server_$rpl_server_number$_rpl_one
+--source include/rpl_connection.inc
+--source include/wait_until_connected_again.inc
+--disable_reconnect
 
 
 --let $include_filename= rpl_reconnect.inc