There were numerous memory leaks in plugin's code and associated code.
During typical run of MTR tests it leaked around 65 megabytes of
objects. As a result they may severely affect long-lived connections.
This patch fixes (almost) all leaks found in the plugin. The exceptions
are two leaks associated with SHOW CREATE TABLE columnstore_table and
getting information of columns of columnstore-handled table. These
should be fixed on the server side and work is on the way.
- occured -> occurred
- reponse -> response
- seperated -> separated
All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer Amazon Web
Services, Inc.
Disable check for correlated subqueries, basically those types of queries transforms
to join (aggr(table2), table1), table2) and post join scalar filter.
Part 1:
As part of MCOL-3776 to address synchronization issue while accessing
the fTimeZone member of the Func class, mutex locks were added to the
accessor and mutator methods. However, this slows down processing
of TIMESTAMP columns in PrimProc significantly as all threads across
all concurrently running queries would serialize on the mutex. This
is because PrimProc only has a single global object for the functor
class (class derived from Func in utils/funcexp/functor.h) for a given
function name. To fix this problem:
(1) We remove the fTimeZone as a member of the Func derived classes
(hence removing the mutexes) and instead use the fOperationType
member of the FunctionColumn class to propagate the timezone values
down to the individual functor processing functions such as
FunctionColumn::getStrVal(), FunctionColumn::getIntVal(), etc.
(2) To achieve (1), a timezone member is added to the
execplan::CalpontSystemCatalog::ColType class.
Part 2:
Several functors in the Funcexp code call dataconvert::gmtSecToMySQLTime()
and dataconvert::mySQLTimeToGmtSec() functions for conversion between seconds
since unix epoch and broken-down representation. These functions in turn call
the C library function localtime_r() which currently has a known bug of holding
a global lock via a call to __tz_convert. This significantly reduces performance
in multi-threaded applications where multiple threads concurrently call
localtime_r(). More details on the bug:
https://sourceware.org/bugzilla/show_bug.cgi?id=16145
This bug in localtime_r() caused processing of the Functors in PrimProc to
slowdown significantly since a query execution causes Functors code to be
processed in a multi-threaded manner.
As a fix, we remove the calls to localtime_r() from gmtSecToMySQLTime()
and mySQLTimeToGmtSec() by performing the timezone-to-offset conversion
(done in dataconvert::timeZoneToOffset()) during the execution plan
creation in the plugin. Note that localtime_r() is only called when the
time_zone system variable is set to "SYSTEM".
This fix also required changing the timezone type from a std::string to
a long across the system.
mcsconfig.h and my_config.h have the following
pre-processor definitions:
1. Conflicting definitions coming from the standard cmake definitions:
- PACKAGE
- PACKAGE_BUGREPORT
- PACKAGE_NAME
- PACKAGE_STRING
- PACKAGE_TARNAME
- PACKAGE_VERSION
- VERSION
2. Conflicting definitions of other kinds:
- HAVE_STRTOLL - this is a dirt in MariaDB headers.
Should be fixed in the server code. my_config.h erroneously
performs "#define HAVE_STRTOLL" instead of "#define HAVE_STRTOLL 1".
in some cases. The former is not CMake compatible style. The latter is.
3. Non-conflicting definitions:
Otherwise, mcsconfig.h and my_config.h should be mutually compatible,
because both are generated by cmake on the same host machine. So
they should have exactly equal definitions like "HAVE_XXX", "SIZEOF_XXX", etc.
Observations:
- It's OK to include both mcsconfig.h and my_config.h providing that we
suppress duplicate definition of the above conflicting types #1 and #2.
- There is no a need to suppress duplicate definitions mentioned in #3,
as they are compatible!
- my_sys.h and m_ctype.h must always follow a CMake configuation header,
either my_config.h or mcsconfig.h (or both).
They must never be included without any preceeding configuration header.
This change make sure that we resolve conflicts by:
- either disallowing inclusion of mcsconfig.h and my_config.h
at the same time
- or by hiding conflicting definitions #1 and #2
(with their later restoring).
- also, by making sure that my_sys.h and m_ctype.h always follow
a CMake configuration file.
Details:
- idb_mysql.h can now only be included only after my_config.h
An attempt to use idb_mysql.h with mcsconfig.h instead of
my_config.h is caught by the "#error" preprocessor directive.
- mariadb_my_sys.h can now be only included after mcsconfig.h.
An attempt to use mariadb_my_sys.h without mcscofig.h
(e.g. with my_config.h) is also caught by "#error".
- collation.h now can now be included in two ways.
It now has the following effective structure:
#if defined(PREFER_MY_CONFIG_H) && defined(MY_CONFIG_H)
// Remember current conflicting definitions on the preprocessor stack
// Undefine current conflicting definitions
#endif
#include "mcsconfig.h"
#include "m_ctype.h"
#if defined(PREFER_MY_CONFIG_H) && defined(MY_CONFIG_H)
# Restore conflicting definitions from the preprocessor stack
#endif
and can be included as follows:
a. using only mcsconfig.h as a configuration header:
// my_config.h must not be included so far
#include "collation.h"
b. using my_config.h as the first included configuration file:
#define PREFER_MY_CONFIG_H // Force conflict resolution
#include "my_config.h" // can be included directly or indirectly
...
#include "collation.h"
Other changes:
- Adding helper header files
utils/common/mcsconfig_conflicting_defs_remember.h
utils/common/mcsconfig_conflicting_defs_restore.h
utils/common/mcsconfig_conflicting_defs_undef.h
to perform conflict resolution easier.
- Removing `#include "collation.h"` from a number of files,
as it's automatically included from rowgroup.h.
- Removing redundant `#include "utils_utf8.h"`.
This change is not directly related to the problem being fixed,
but it's nice to remove redundant directives for both collation.h
and utils_utf8.h from all the files that do not really need them.
(this change could probably have gone as a separate commit)
- Changing my_init() to MY_INIT(argv[0]) in the MCS services sources.
After the fix of the complitation failure it appeared that ColumnStore
services compiled with the debug build crash due to recent changes in
safemalloc. The crash happened in strcmp() with `my_progname` as an argument
(where my_progname is a mysys global variable). This problem should
probably be fixed on the server side as well to avoid passing NULL.
But, the majority of MariaDB executable programs also use MY_INIT(argv[0])
rather than my_init(). So let's make MCS do like the other programs do.
Original SH implementation sends the result set back to the client
thus it can't be used in INSERT..SELECT, SELECT INTO OUTFILE,CREATE
TABLE AS SELECT etc.
CLX-77 feature has been backported into MDB to enable SH to run
query part of the mentioned queries.
This happens in external_lock() whilst locking the table.
Fixes LIMIT=1 optimization for EXISTS_SUBS subqueries.
external_lock() contains if condition that gives false positive
for SH + pushed conditions.
external_lock() now resets in_subquery_conversion_threshold
variable that governs IN_INTO_SUBQUERY optimization for
queries run in table mode.
external_lock() now purges dynamicall allocated condInfo for
SH and DH execution path.
Commented out UNION check b/c if condition gives false positives
and silently enables table mode execution for queries w/o
UNION.
