There were two problems: RESET QUERY CACHE took a long time to complete
and other threads were blocked during this time.

The patch does three things:
  1 fixes a bug with improper use of test-lock-test_again technique.
      AKA Double-Checked Locking is applicable here only in few places.
  2 Somewhat improves performance of RESET QUERY CACHE.
      Do my_hash_reset() instead of deleting elements one by one.  Note
      however that the slowdown also happens when inserting into sorted
      list of free blocks, should be rewritten using balanced tree.
  3 Makes RESET QUERY CACHE non-blocking.
      The patch adjusts the locking protocol of the query cache in the
      following way: it introduces a flag flush_in_progress, which is
      set when Query_cache::flush_cache() is in progress.  This call
      sets the flag on enter, and then releases the lock.  Every other
      call is able to acquire the lock, but does nothing if
      flush_in_progress is set (as if the query cache is disabled).
      The only exception is the concurrent calls to
      Query_cache::flush_cache(), that are blocked until the flush is
      over.  When leaving Query_cache::flush_cache(), the lock is
      acquired and the flag is reset, and one thread waiting on
      Query_cache::flush_cache() (if any) is notified that it may
      proceed.

  
Fix for the bug in mysql-test-run.pl which prevents other tests succeed
after IM-test failure.
  
The idea of the fix of BUG#20716 is to:
  1. Check each SHOW INSTANCES statement, add necessary "sleep" instruction before;
  2. Move all environment checkings into the one file and include it everywhere.

into  moonlight.intranet:/home/tomash/src/mysql_ab/mysql-5.0-bug21013

           and Stored Procedure

The essence of the bug was that for every re-execution of stored
routine or prepared statement new items for character set conversions
were created, thus increasing the number of items and the time of their
processing, and creating memory leak.

No test case is provided since current test suite can't cover such type
of bugs.

into  moonlight.intranet:/home/tomash/src/mysql_ab/mysql-5.0-bug18630

           context.

Routine arguments were evaluated in the security context of the routine
itself, not in the caller's context.

The bug is fixed the following way:

  - Item_func_sp::find_and_check_access() has been split into two
    functions: Item_func_sp::find_and_check_access() itself only
    finds the function and check that the caller have EXECUTE privilege
    on it.  New function set_routine_security_ctx() changes security
    context for SUID routines and checks that definer have EXECUTE
    privilege too.

  - new function sp_head::execute_trigger() is called from
    Table_triggers_list::process_triggers() instead of
    sp_head::execute_function(), and is effectively just as the
    sp_head::execute_function() is, with all non-trigger related code
    removed, and added trigger-specific security context switch.

  - call to Item_func_sp::find_and_check_access() stays outside
    of sp_head::execute_function(), and there is a code in
    sql_parse.cc before the call to sp_head::execute_procedure() that
    checks that the caller have EXECUTE privilege, but both
    sp_head::execute_function() and sp_head::execute_procedure() call
    set_routine_security_ctx() after evaluating their parameters,
    and restore the context after the body is executed.

into  bodhi.local:/opt/local/work/mysql-5.0-runtime

into  dl145k.mysql.com:/data0/mkindahl/bk/mysql-5.0-rpl

when dropping/creating tables"

into  bodhi.local:/opt/local/work/mysql-5.0-runtime-merge-41

into  bodhi.local:/opt/local/work/mysql-5.0-runtime-merge-41

into  chilla.local:/home/mydev/mysql-5.0-amerge

into  trift2.:/M50/mysql-5.0

into  dl145k.mysql.com:/data0/mkindahl/bk/MERGE/mysql-5.0-merge

into  bodhi.local:/opt/local/work/mysql-5.0-runtime-merge-41

into  trift2.:/M50/mysql-5.0

into  gbichot3.local:/home/mysql_src/mysql-5.0

into  orca.ndb.mysql.com:/space_old/pekka/ndb/version/my50-1.2167.1.2

fails"

into  orca.ndb.mysql.com:/space_old/pekka/ndb/version/my50

into  dsl-hkigw8-feb1fb00-100.dhcp.inet.fi:/usr_rh9/home/elkin.rh9/MySQL/TEAM/FIXES/5.0/20919_temp_nlog

into  trift2.:/M50/mysql-5.0

into  trift2.:/M50/back23-5.0

into  orca.ndb.mysql.com:/space_old/pekka/ndb/version/my50-bug20847

into  orca.ndb.mysql.com:/space_old/pekka/ndb/version/my50-bug20847

closing temp tables through end_thread
had a flaw in binlog-off branch of close_temporary_tables where
next table to close was reset via table->next
 for (table= thd->temporary_tables; table; table= table->next)
which was wrong since the current table instance got destoyed at
	close_temporary(table, 1);

The fix adapts binlog-on branch method to engage the loop's internal 'next' variable which holds table->next prior table's destoying.

between pointer to function and pointer to object.