According to new numbering scheme mysql-next-mr does not have
its own version. Some version placeholder is used instead.
It's been agreed that 5.5.99 will be used as a placeholder.
-------------------------------------------------------------
revno: 2877
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: 35164-6.0
timestamp: Wed 2008-10-15 19:53:18 -0300
message:
Bug#35164: Large number of invalid pthread_attr_setschedparam calls
Bug#37536: Thread scheduling causes performance degradation at low thread count
Bug#12702: Long queries take 100% of CPU and freeze other applications under Windows
The problem is that although having threads with different priorities
yields marginal improvements [1] in some platforms [2], relying on some
statically defined priorities (QUERY_PRIOR and WAIT_PRIOR) to play well
(or to work at all) with different scheduling practices and disciplines
is, at best, a shot in the dark as the meaning of priority values may
change depending on the scheduling policy set for the process.
Another problem is that increasing priorities can hurt other concurrent
(running on the same hardware) applications (such as AMP) by causing
starvation problems as MySQL threads will successively preempt lower
priority processes. This can be evidenced by Bug#12702.
The solution is to not change the threads priorities and rely on the
system scheduler to perform its job. This also enables a system admin
to increase or decrease the scheduling priority of the MySQL process,
if intended.
Furthermore, the internal wrappers and code for changing the priority
of threads is being removed as they are now unused and ancient.
1. Due to unintentional side effects. On Solaris this could artificially
help benchmarks as calling the priority changing syscall millions of
times is more beneficial than the actual setting of the priority.
2. Where it actually works. It has never worked on Linux as the default
scheduling policy SCHED_OTHER only accepts the static priority 0.
configure.in:
Remove checks for functions that are not used anymore.
include/config-netware.h:
Remove unused define.
include/my_pthread.h:
Remove thread priority changing wrappers.
mysys/my_pthread.c:
Remove thread priority changing wrappers. They do not work properly
and their implementations were incorrectly protected by a check for
HAVE_PTHREAD_SETSCHEDPARAM.
mysys/thr_alarm.c:
Remove meaningless (100) increase of a thread priority.
sql/mysql_priv.h:
Remove meaningless thread priority values.
sql/mysqld.cc:
Don't change thread priorities.
sql/slave.cc:
Don't change thread priorities.
sql/slave.h:
Update function prototype.
sql/sql_parse.cc:
Don't change thread priorities.
sql/sql_prepare.cc:
Don't change thread priorities.
sql/unireg.h:
Mark flag as obsolete.
storage/innobase/handler/ha_innodb.cc:
Remove use of obsolete flag and associated behavior.
storage/innobase/include/srv0srv.h:
Remove use of obsolete flag and associated variables.
storage/innobase/os/os0thread.c:
Remove use of obsolete flag and associated behavior.
storage/innobase/srv/srv0srv.c:
Remove use of obsolete flag and associated variables.
A build "--without-server" fails if using "--with-ssl" (YaSSL)
The problem was the lack of directory "extra" in a build
which did not include the server.
configure.in:
1) Ensure "extra" is in the list of client directories.
2) Always handle the client directories first, as they will
be contained in every build (we have client-only, but not
server-only).
"have_profiling"
1) Renamed have_community_features server system variable to
have_profiling.
2) Removed eable-community-features configure option and
ENABLE_COMMUNITY_FEATURES macro.
3) Removed COMMUNITY_SERVER macro and replaced its usage by
ENABLED_PROFILING.
Only --enable-profiling is now needed to enable profiling.
It was the only existing "community feature", so there was
no need for both configure options.
Using --enable-community-features will give a warning message
since it no longer exists.
Backport from 6.0 to 5.1.
Only those sync points are included, which are used in debug_sync.test.
The Debug Sync Facility allows to place synchronization points
in the code:
open_tables(...)
DEBUG_SYNC(thd, "after_open_tables");
lock_tables(...)
When activated, a sync point can
- Send a signal and/or
- Wait for a signal
Nomenclature:
- signal: A value of a global variable that persists
until overwritten by a new signal. The global
variable can also be seen as a "signal post"
or "flag mast". Then the signal is what is
attached to the "signal post" or "flag mast".
- send a signal: Assign the value (the signal) to the global
variable ("set a flag") and broadcast a
global condition to wake those waiting for
a signal.
- wait for a signal: Loop over waiting for the global condition until
the global value matches the wait-for signal.
Please find more information in the top comment in debug_sync.cc
or in the worklog entry.
.bzrignore:
WL#4259 - Debug Sync Facility
Added the symbolic link libmysqld/debug_sync.cc.
CMakeLists.txt:
WL#4259 - Debug Sync Facility
Added definition for ENABLED_DEBUG_SYNC.
configure.in:
WL#4259 - Debug Sync Facility
Added definition for ENABLED_DEBUG_SYNC.
include/my_sys.h:
WL#4259 - Debug Sync Facility
Added definition for the DEBUG_SYNC_C macro.
libmysqld/CMakeLists.txt:
WL#4259 - Debug Sync Facility
Added sql/debug_sync.cc.
libmysqld/Makefile.am:
WL#4259 - Debug Sync Facility
Added sql/debug_sync.cc.
mysql-test/include/have_debug_sync.inc:
WL#4259 - Debug Sync Facility
New include file.
mysql-test/mysql-test-run.pl:
WL#4259 - Debug Sync Facility
Added option --debug_sync_timeout.
mysql-test/r/debug_sync.result:
WL#4259 - Debug Sync Facility
New test result.
mysql-test/r/have_debug_sync.require:
WL#4259 - Debug Sync Facility
New require file.
mysql-test/t/debug_sync.test:
WL#4259 - Debug Sync Facility
New test file.
mysys/my_static.c:
WL#4259 - Debug Sync Facility
Added definition for debug_sync_C_callback_ptr.
mysys/thr_lock.c:
WL#4259 - Debug Sync Facility
Added sync point "wait_for_lock".
sql/CMakeLists.txt:
WL#4259 - Debug Sync Facility
Added debug_sync.cc and debug_sync.h.
sql/Makefile.am:
WL#4259 - Debug Sync Facility
Added debug_sync.cc and debug_sync.h.
sql/debug_sync.cc:
WL#4259 - Debug Sync Facility
New source file.
sql/debug_sync.h:
WL#4259 - Debug Sync Facility
New header file.
sql/mysqld.cc:
WL#4259 - Debug Sync Facility
Added opt_debug_sync_timeout.
Added calls to debug_sync_init() and debug_sync_end().
Fixed a purecov comment (unrelated).
sql/set_var.cc:
WL#4259 - Debug Sync Facility
Added server variable "debug_sync".
sql/set_var.h:
WL#4259 - Debug Sync Facility
Added declaration for server variable "debug_sync".
sql/share/errmsg.txt:
WL#4259 - Debug Sync Facility
Added error messages ER_DEBUG_SYNC_TIMEOUT and ER_DEBUG_SYNC_HIT_LIMIT.
sql/sql_base.cc:
WL#4259 - Debug Sync Facility
Added sync points "after_flush_unlock" and "before_lock_tables_takes_lock".
sql/sql_class.cc:
WL#4259 - Debug Sync Facility
Added initialization for debug_sync_control to THD::THD.
Added calls to debug_sync_init_thread() and debug_sync_end_thread().
sql/sql_class.h:
WL#4259 - Debug Sync Facility
Added element debug_sync_control to THD.
storage/myisam/myisamchk.c:
Fixed a typo in an error message string (unrelated).
