In test for bug#15933 we have to wait for all disconnects to finish to avoid

a race between updating and checking Max_used_connections.  This is done in
a loop until either disconnect finished or timeout expired.  In a latter case
the test will fail.

mysql-test/r/status.result

@@ -26,20 +26,20 @@ Last_query_cost	0.000000
 FLUSH STATUS;
 SHOW STATUS LIKE 'max_used_connections';
 Variable_name	Value
-Max_used_connections	3
+Max_used_connections	1
 SET @save_thread_cache_size=@@thread_cache_size;
 SET GLOBAL thread_cache_size=3;
 SHOW STATUS LIKE 'max_used_connections';
 Variable_name	Value
-Max_used_connections	5
+Max_used_connections	3
 FLUSH STATUS;
 SHOW STATUS LIKE 'max_used_connections';
 Variable_name	Value
-Max_used_connections	4
+Max_used_connections	2
 SHOW STATUS LIKE 'max_used_connections';
 Variable_name	Value
-Max_used_connections	5
+Max_used_connections	3
 SHOW STATUS LIKE 'max_used_connections';
 Variable_name	Value
-Max_used_connections	6
+Max_used_connections	4
 SET GLOBAL thread_cache_size=@save_thread_cache_size;

mysql-test/t/status.test

@@ -36,6 +36,10 @@ reap;
 show status like 'Table_lock%';
 drop table t1;
 
+disconnect con2;
+disconnect con1;
+connection default;
+
 # End of 4.1 tests
 
 #
@@ -60,48 +64,81 @@ show status like 'last_query_cost';
 #   taking a thread from the cache as well as when creating new threads
 #
 
-# Previous test uses con1, con2.  If we disconnect them, there will be
-# a race on when exactly this will happen, so we better leave them as
-# is.
-connection default;
+# Wait for at most $disconnect_timeout seconds for disconnects to finish.
+let $disconnect_timeout = 10;
 
-# Reset max_used_connections from previous tests.
+# Wait for any previous disconnects to finish.
 FLUSH STATUS;
+--disable_query_log
+--disable_result_log
+eval SET @wait_left = $disconnect_timeout;
+let $max_used_connections = `SHOW STATUS LIKE 'max_used_connections'`;
+eval SET @max_used_connections = SUBSTRING('$max_used_connections', 21)+0;
+let $wait_more = `SELECT @max_used_connections != 1 && @wait_left > 0`;
+while ($wait_more)
+{
+  sleep 1;
+  FLUSH STATUS;
+  SET @wait_left = @wait_left - 1;
+  let $max_used_connections = `SHOW STATUS LIKE 'max_used_connections'`;
+  eval SET @max_used_connections = SUBSTRING('$max_used_connections', 21)+0;
+  let $wait_more = `SELECT @max_used_connections != 1 && @wait_left > 0`;
+}
+--enable_query_log
+--enable_result_log
+
+# Prerequisite.
 SHOW STATUS LIKE 'max_used_connections';
 
 # Save original setting.
 SET @save_thread_cache_size=@@thread_cache_size;
 SET GLOBAL thread_cache_size=3;
 
-connect (con3,localhost,root,,);
-connect (con4,localhost,root,,);
+connect (con1,localhost,root,,);
+connect (con2,localhost,root,,);
 
-connection con3;
-disconnect con4;
+connection con1;
+disconnect con2;
 
 # Check that max_used_connections still reflects maximum value.
 SHOW STATUS LIKE 'max_used_connections';
 
 # Check that after flush max_used_connections equals to current number
-# of connections.
+# of connections.  First wait for previous disconnect to finish.
 FLUSH STATUS;
+--disable_query_log
+--disable_result_log
+eval SET @wait_left = $disconnect_timeout;
+let $max_used_connections = `SHOW STATUS LIKE 'max_used_connections'`;
+eval SET @max_used_connections = SUBSTRING('$max_used_connections', 21)+0;
+let $wait_more = `SELECT @max_used_connections != 2 && @wait_left > 0`;
+while ($wait_more)
+{
+  sleep 1;
+  FLUSH STATUS;
+  SET @wait_left = @wait_left - 1;
+  let $max_used_connections = `SHOW STATUS LIKE 'max_used_connections'`;
+  eval SET @max_used_connections = SUBSTRING('$max_used_connections', 21)+0;
+  let $wait_more = `SELECT @max_used_connections != 2 && @wait_left > 0`;
+}
+--enable_query_log
+--enable_result_log
+# Check that we don't count disconnected thread any longer.
 SHOW STATUS LIKE 'max_used_connections';
 
 # Check that max_used_connections is updated when cached thread is
 # reused...
-connect (con4,localhost,root,,);
+connect (con2,localhost,root,,);
 SHOW STATUS LIKE 'max_used_connections';
 
 # ...and when new thread is created.
-connect (con5,localhost,root,,);
+connect (con3,localhost,root,,);
 SHOW STATUS LIKE 'max_used_connections';
 
 # Restore original setting.
 connection default;
 SET GLOBAL thread_cache_size=@save_thread_cache_size;
 
-disconnect con5;
-disconnect con4;
 disconnect con3;
 disconnect con2;
 disconnect con1;