The problem from a user point of view was that on Solaris the
time related functions (e.g. NOW(), SYSDATE(), etc) would always
return a fixed time.
This bug was happening due to a logic in the time retrieving
wrapper function which would only call the time() function every
half second. This interval between calls would be calculated
using the gethrtime() and the logic relied on the fact that time
returned by it is monotonic.
Unfortunately, due to bugs in the gethrtime() implementation,
there are some cases where the time returned by it can drift
(See Solaris bug id 6600939), potentially causing the interval
calculation logic to fail.
Since newer versions of Solaris (10+) have alleviated the
performance degradation associated with time(2), the solution is
to simply directly rely on time() at each invocation.
This simplification has an upside that it allows us to eliminate
a lock which was used to control access to the variables used
to track the half second interval, thus improving the overall
scalability of timekeeping related functions (e.g. NOW()).
Benchmarks runs have shown no significant degradation associated
with this change. With this, there are actually improvements in
performance for cases involving many connections.
In summary, the changes introduced by this patch are:
a) my_time() and my_micro_time_and_time() no longer use gethrtime().
Instead, time() and gettimeofdate() are used correspondingly.
b) my_micro_time() is changed to not use gethrtime() so as to
have the same time source as my_micro_time_and_time().
There shouldn't be any performance impact from this change
since this function is used only a few times during statement
execution and, on Solaris, gettimeofday() shows acceptable
performance.
and 'THREAD_SAFE_CLIENT'.
As of MySQL 5.5, we no longer support non-threaded
builds. This patch removes all references to the
obsolete THREAD and THREAD_SAFE_CLIENT preprocessor
symbols. These were used to distinguish between
threaded and non-threaded builds.
Bug#24509 - 2048 file descriptor limit on windows needs increasing, also
WL#3049 - improved Windows I/O
The patch replaces the use of the POSIX I/O interfaces in mysys on Windows with
the Win32 API calls (CreateFile, WriteFile, etc). The Windows HANDLE for the open
file is stored in the my_file_info struct, along with a flag for append mode
because the Windows API does not support opening files in append mode in all cases)
The default max open files has been increased to 16384 and can be increased further
by setting --max-open-files=<value> during the server start.
Another major change in this patch that almost all Windows specific file IO code
has been moved to a new file my_winfile.c, greatly reducing the amount of code
in #ifdef blocks within mysys, thus improving readability.
Minor enhancements:
- my_(f)stat() is changed to use __stati64 structure with 64 file size
and timestamps. It will return correct file size now (C runtime implementation
used to report outdated information)
- my_lock on Windows is prepared to handle additional timeout parameter
- after review : changed __WIN__ to _WIN32 in the new and changed code.
--long-query-time is now given in seconds with microseconds as decimals
--min_examined_row_limit added for slow query log
long_query_time user variable is now double with 6 decimals
Added functions to get time in microseconds
Added faster time() functions for system that has gethrtime() (Solaris)
We now do less time() calls.
Added field->in_read_set() and field->in_write_set() for easier field manipulation by handlers
set_var.cc and my_getopt() can now handle DOUBLE variables.
All time() calls changed to my_time()
my_time() now does retry's if time() call fails.
Added debug function for stopping in mysql_admin_table() when tables are locked
Some trivial function and struct variable renames to avoid merge errors.
Fixed compiler warnings
Initialization of some time variables on windows moved to my_init()
Moved .progress files into the log directory
Moved 'cluster' database tables into the MySQL database, to not have 'cluster' beeing a reserved database name
Fixed bug where mysqld got a core dump when trying to use a table created by MySQL 3.23
Fixed some compiler warnings
Fixed small memory leak in libmysql
Note that this doesn't changeset doesn't include the new mysqldump.c code required to run some tests. This will be added when I merge 5.0 to 5.1
Call pthread_mutex_destroy() on not used mutex.
Changed comments in .h and .c files from // -> /* */
Added detection of mutex on which one didn't call pthread_mutex_destroy()
Fixed bug in create_tmp_field() which causes a memory overrun in queries that uses "ORDER BY constant_expression"
Added optimisation for ORDER BY NULL
