high load
MySQL server could crash if two or more threads would initiate query
cache resize at the moments very close in time.
The problem was introduced with the fix of bug 21051 in 5.0 and 5.1:
simultaneous query cache resizes would wait for the first one in
progress, but then each thread would try to finish the operation,
accessing the data that was already reset (attempt to dereference
'bins' pointer, which may be NULL already).
The solution is to check after synchronization if another thread has
done the reset already (test 'query_cache_size > 0' again).
No test case is provided because the bug is a subject to a race.
- added extra cluster connect inicator bit for better handeling of delacation of event operations on cluster disconnect
- added extra assert to try to track down valgrind issue
The build scripts in general, using automake, autoconf, etc, contain several
special commands and work around all related to the way the bison code in the
parser is built, for sql/sql_yacc.yy. These work arounds, accumulated over
time during development, ultimately cause the build scripts to be unstable
and cause build defects by not enforcing dependencies.
This fix simplifies the build process and aligns it with the automake tooling,
which provides native support for bison and *.yy files.
In particular, the following problem have been fixed:
- dependencies with sql_yacc.cc were not honored (Bug 21029), leading to
corrupted builds,
- the work around introduced by Bug 24557, to cleanup the generated files
sql_yacc.h and sql_yacc.cc, has been removed,
- the generated makefile, in a source distribution, used to destroy the files
sql_yacc.h and sql_yacc.cc on a 'make clean' target. This has been fixed:
these files are now removed by make maintainer-clean.
- The root cause of the problem found with gcc 4.1 (see Bug 24619) has been
clearly documented, and the "sed" hack has been replaced by a cleaner
work around, when building the code with bison 1.875.
- Removed the file sql/sql_yacc.yy.bak, added by WL 3031 by accident.
- Removed the unnecessary AM_YFLAG= --debug introduced by WL 3432, since
the compiling option DBUG_OFF takes precedence when setting YYDEBUG.
Before this fix, the command SHOW ENGINE <name> STATUS would:
- print a warning if the engine name is unknown,
- proceed and implement the same behavior as SHOW ENGINE ALL STATUS,
and list the status of all the storage engines registered.
In particular, this behavior caused confusion about the command :
SHOW ENGINE MUTEX STATUS, which as a side effect would print the status
of the innodb engine when that engine is registered.
Also, before this fix, every time an unknown engine name was substituted by
the default engine (which happen unless SQL_MODE NO_ENGINE_SUBSTITUTION is
set), a malformed warning was raised.
For example, the command ALTER TABLE T1 ENGINE = X would print :
Warnings:
Error 1286 Unknown table engine 'X'
With this fix:
SHOW ENGINE <name> STATUS|LOGS|MUTEX
always fails with an error when the engine <name> is unknown.
For other commands, warnings about unknown engines are raised as:
Warnings:
Warning 1286 Unknown table engine 'X'
In other words, engine substitution never affect the SHOW ENGINE command,
since this would lead to very confusing results.
