Analysis:
-------------
If server is started with limit of MAX_CONNECTIONS and
MAX_USER_CONNECTIONS then only MAX_USER_CONNECTIONS of any particular
users can be connected to server and total MAX_CONNECTIONS of client can
be connected to server.
Server maintains a counter for total CONNECTIONS and total CONNECTIONS
from particular user.
Here, MAX_CONNECTIONS of connections are created to server. Out of this
MAX_CONNECTIONS, connections from particular user (say USER1) are
also created. The connections from USER1 is lesser than
MAX_USER_CONNECTIONS. After that there was one more connection request from
USER1. Since USER1 can still create connections as he havent reached
MAX_USER_CONNECTIONS, server increments counter of CONNECTIONS per user.
As server already has MAX_CONNECTIONS of connections, next check to total
CONNECTION count fails. In this case control is returned WITHOUT
decrementing the CONNECTIONS per user. So the counter per user CONNECTIONS goes
on incrementing for each attempt until current connections are closed.
And because of this counter per CONNECTIONS reached MAX_USER_CONNECTIONS.
So, next connections form USER1 user always returns with MAX_USER_CONNECTION
limit error, even when total connection to sever are less than MAX_CONNECTIONS.
Fix:
-------------
This issue is occurred because of not handling counters properly in the
server. Changed the code to handle per user connection counters properly.
handle_segfault is the signal handler code of mysqld. however, it makes
calls to potentially unsafe functions localtime_r, fprintf, fflush.
include/my_stacktrace.h:
Add safe versions of itoa() write() and snprintf().
libmysqld/CMakeLists.txt:
Move signal handler to separate file.
mysys/stacktrace.c:
Remove unsafe function calls.
sql/CMakeLists.txt:
Move signal handler to separate file.
sql/mysqld.cc:
Move signal handler to separate file.
sql/set_var.h:
Add missing #include dependency.
sql/sys_vars.cc:
Cleanup .h and .cc files.
sql/sys_vars.h:
Cleanup .h and .cc files.
cmake/os/SunOS.cmake:
Remove TARGET_OS_SOLARIS
config.h.cmake:
Remove TARGET_OS_SOLARIS
Add PTHREAD_ONCE_INITIALIZER
configure.cmake:
Add function for testing whether we need { PTHREAD_ONCE_INIT } rather than PTHREAD_ONCE_INIT
include/my_pthread.h:
Use PTHREAD_ONCE_INITIALIZER if set by cmake.
include/mysql/psi/mysql_file.h:
Include my_global.h first, to get correct platform definitions.
mysys/ptr_cmp.c:
Hide the unused static functions in #ifdef's on solaris.
Use __sun (defined by both gcc and SunPro cc) rather than TARGET_OS_SOLARIS
sql/my_decimal.cc:
Include my_global.h first, to get correct platform definitions.
sql/mysqld.cc:
Fix signed/unsigned comparison warning.
sql/sql_audit.h:
Include my_global.h first, to get correct platform definitions.
sql/sql_plugin.h:
Include my_global.h first, to get correct platform definitions.
sql/sql_show.cc:
Fix: warning: cast from pointer to integer of different size
sql/sys_vars.h:
Use reinterpret_cast rather than c-style cast.
storage/perfschema/pfs_instr.cc:
Include my_global.h first, to get correct platform definitions.
Fix warnings related to the use of the deprecated gets() function
and passing NULL to non-pointer argument of the sys_var constructor.
plugin/auth/dialog.c:
Do not use the deprecated gets() function.
sql/sys_vars.h:
Do not pass NULL to a non-pointer argument of the sys_var constructor.
thread-specific variables weren't set when we load error message files.
per-file comments:
libmysqld/lib_sql.cc
Bug#53251 mysql_library_init fails on second execution with embedded library
we need to call my_thread_init() once more. Normally it's called at the my_init()
stage but that doesn't happen on the second my_init() call.
sql/derror.cc
Bug#53251 mysql_library_init fails on second execution with embedded library
use default errors for the embedded server.
sql/mysqld.cc
Bug#53251 mysql_library_init fails on second execution with embedded library
unregister server errors in clean_up(). Without it the error list contains
that on the second mysql_server_init() which is not good.
sql/set_var.cc
Bug#53251 mysql_library_init fails on second execution with embedded library
sys_var::cleanup() call instead of the destructor
sql/set_var.h
Bug#53251 mysql_library_init fails on second execution with embedded library
sys_var::cleanup() introduced instead of the destructor
sql/sys_vars.h
Bug#53251 mysql_library_init fails on second execution with embedded library
Sys_var_charptr::cleanup() implemented
Fix compiler warnings due to: a mismatch in the prototypes for
check_access and implicit conversions from double to ulonglong
and vice-versa.
mysys/my_getopt.c:
Explicit conversion from ulonglong to double. Might need to
be tweaked in the future.
sql/sql_parse.h:
Make prototype equal to the case when not compiling under embedded.
sql/sys_vars.cc:
Explicit conversion from ulonglong to double. Destination var
is a ulonglong.
sql/sys_vars.h:
Explicit conversion from ulonglong to double. Might need to
be tweaked in the future.
Essentially, the problem is that safemalloc is excruciatingly
slow as it checks all allocated blocks for overrun at each
memory management primitive, yielding a almost exponential
slowdown for the memory management functions (malloc, realloc,
free). The overrun check basically consists of verifying some
bytes of a block for certain magic keys, which catches some
simple forms of overrun. Another minor problem is violation
of aliasing rules and that its own internal list of blocks
is prone to corruption.
Another issue with safemalloc is rather the maintenance cost
as the tool has a significant impact on the server code.
Given the magnitude of memory debuggers available nowadays,
especially those that are provided with the platform malloc
implementation, maintenance of a in-house and largely obsolete
memory debugger becomes a burden that is not worth the effort
due to its slowness and lack of support for detecting more
common forms of heap corruption.
Since there are third-party tools that can provide the same
functionality at a lower or comparable performance cost, the
solution is to simply remove safemalloc. Third-party tools
can provide the same functionality at a lower or comparable
performance cost.
The removal of safemalloc also allows a simplification of the
malloc wrappers, removing quite a bit of kludge: redefinition
of my_malloc, my_free and the removal of the unused second
argument of my_free. Since free() always check whether the
supplied pointer is null, redudant checks are also removed.
Also, this patch adds unit testing for my_malloc and moves
my_realloc implementation into the same file as the other
memory allocation primitives.
client/mysqldump.c:
Pass my_free directly as its signature is compatible with the
callback type -- which wasn't the case for free_table_ent.
Bug#20837 Apparent change of isolation level during transaction,
Bug#46527 COMMIT AND CHAIN RELEASE does not make sense,
Bug#53343 completion_type=1, COMMIT/ROLLBACK AND CHAIN don't
preserve the isolation level
Bug#53346 completion_type has strange effect in a stored
procedure/prepared statement
Make thd->tx_isolation mean strictly "current transaction
isolation level"
Make thd->variables.tx_isolation mean "current session isolation
level".
The current transaction isolation level is now established
at transaction start. If there was a SET TRANSACTION
ISOLATION LEVEL statement, the value is taken from it.
Otherwise, the session value is used.
A change in a session value, made while a transaction is active,
whereas still allowed, no longer has any effect on the
current transaction isolation level. This is an incompatible
change.
A change in a session isolation level, made while there is
no active transaction, overrides SET TRANSACTION statement,
if there was any.
Changed the impelmentation to not look at @@session.completion_type
in the parser, and thus fixed Bug#53346.
Changed the parser to not allow AND NO CHAIN RELEASE,
and thus fixed Bug#46527.
Changed the transaction API to take the current transaction
isolation level into account:
- BEGIN/COMMIT now do preserve the current transaction
isolation level if chaining is on.
- implicit commit, XA COMMIT or XA ROLLBACK or autocommit don't.
This patch:
- Moves all definitions from the mysql_priv.h file into
header files for the component where the variable is
defined
- Creates header files if the component lacks one
- Eliminates all include directives from mysql_priv.h
- Eliminates all circular include cycles
- Rename time.cc to sql_time.cc
- Rename mysql_priv.h to sql_priv.h
Bug#16565 mysqld --help --verbose does not order variablesBug#20413 sql_slave_skip_counter is not shown in show variables
Bug#20415 Output of mysqld --help --verbose is incomplete
Bug#25430 variable not found in SELECT @@global.ft_max_word_len;
Bug#32902 plugin variables don't know their names
Bug#34599 MySQLD Option and Variable Reference need to be consistent in formatting!
Bug#34829 No default value for variable and setting default does not raise error
Bug#34834 ? Is accepted as a valid sql mode
Bug#34878 Few variables have default value according to documentation but error occurs
Bug#34883 ft_boolean_syntax cant be assigned from user variable to global var.
Bug#37187 `INFORMATION_SCHEMA`.`GLOBAL_VARIABLES`: inconsistent status
Bug#40988 log_output_basic.test succeeded though syntactically false.
Bug#41010 enum-style command-line options are not honoured (maria.maria-recover fails)
Bug#42103 Setting key_buffer_size to a negative value may lead to very large allocations
Bug#44691 Some plugins configured as MYSQL_PLUGIN_MANDATORY in can be disabled
Bug#44797 plugins w/o command-line options have no disabling option in --help
Bug#46314 string system variables don't support expressions
Bug#46470 sys_vars.max_binlog_cache_size_basic_32 is broken
Bug#46586 When using the plugin interface the type "set" for options caused a crash.
Bug#47212 Crash in DBUG_PRINT in mysqltest.cc when trying to print octal number
Bug#48758 mysqltest crashes on sys_vars.collation_server_basic in gcov builds
Bug#49417 some complaints about mysqld --help --verbose output
Bug#49540 DEFAULT value of binlog_format isn't the default value
Bug#49640 ambiguous option '--skip-skip-myisam' (double skip prefix)
Bug#49644 init_connect and \0
Bug#49645 init_slave and multi-byte characters
Bug#49646 mysql --show-warnings crashes when server dies
CMakeLists.txt:
Bug#44691 Some plugins configured as MYSQL_PLUGIN_MANDATORY in can be disabled
client/mysql.cc:
don't crash with --show-warnings when mysqld dies
config/ac-macros/plugins.m4:
Bug#44691 Some plugins configured as MYSQL_PLUGIN_MANDATORY in can be disabled
include/my_getopt.h:
comments
include/my_pthread.h:
fix double #define
mysql-test/mysql-test-run.pl:
run sys_vars suite by default
properly recognize envirinment variables (e.g. MTR_MAX_SAVE_CORE) set to 0
escape gdb command line arguments
mysql-test/suite/sys_vars/r/rpl_init_slave_func.result:
init_slave+utf8 bug
mysql-test/suite/sys_vars/t/rpl_init_slave_func.test:
init_slave+utf8 bug
mysys/my_getopt.c:
Bug#34599 MySQLD Option and Variable Reference need to be consistent in formatting!
Bug#46586 When using the plugin interface the type "set" for options caused a crash.
Bug#49640 ambiguous option '--skip-skip-myisam' (double skip prefix)
mysys/typelib.c:
support for flagset
sql/ha_ndbcluster.cc:
backport from telco tree
sql/item_func.cc:
Bug#49644 init_connect and \0
Bug#49645 init_slave and multi-byte characters
sql/sql_builtin.cc.in:
Bug#44691 Some plugins configured as MYSQL_PLUGIN_MANDATORY in can be disabled
sql/sql_plugin.cc:
Bug#44691 Some plugins configured as MYSQL_PLUGIN_MANDATORY in can be disabled
Bug#32902 plugin variables don't know their names
Bug#44797 plugins w/o command-line options have no disabling option in --help
sql/sys_vars.cc:
all server variables are defined here
storage/myisam/ft_parser.c:
remove unnecessary updates of param->quot
storage/myisam/ha_myisam.cc:
myisam_* variables belong here
strings/my_vsnprintf.c:
%o and %llx
unittest/mysys/my_vsnprintf-t.c:
%o and %llx tests
vio/viosocket.c:
bugfix: fix @@wait_timeout to work with socket timeouts (vs. alarm thread)
