The root cause of the crash is that a TranxNode is freed before it is used.
A TranxNode is allocated and inserted into the active list each time 
a log event is written and flushed into the binlog file. 
The memory for TranxNode is allocated with thd_alloc and will be freed 
at the end of the statement. The after_commit/after_rollback callback
was supposed to be called before the end of each statement and remove the node from
the active list. However this assumption is not correct in all cases(e.g. call 
'CREATE TEMPORARY TABLE myisam_t SELECT * FROM innodb_t' in a transaction
 and delete all temporary tables automatically when a session closed), 
and can cause the memory allocated for TranxNode be freed
before it was removed from the active list. So The TranxNode pointer in the active
list would become a wild pointer and cause the crash.

After this patch, We have a class called a TranxNodeAllocate which manages the memory
for allocating and freeing TranxNode. It uses my_malloc to allocate memory.

into mysql-trunk-bugfixing.

Original revision:
------------------------------------------------------------
revision-id: vvaintroub@mysql.com-20091222115311-bam0xorumd8gvjyo
parent: mattias.jonsson@sun.com-20091221104426-x2e6c93x8iik4fo0
committer: Vladislav Vaintroub <vvaintroub@mysql.com>
branch nick: mysql-next-mr-bugfixing
timestamp: Tue 2009-12-22 12:53:11 +0100
message:
  Bug#49834 - fixed a bug introduced by mismerge.
  restore original innobase version
------------------------------------------------------------

by shared embedded library)

Conflicts:
  - storage/ibmdb2i/ha_ibmdb2i.cc

Recommit of patch:
http://lists.mysql.com/commits/91400

Test case only (code part was pushes as bug-49028)

Post-merge fix: wait for statement result before disconnecting. Otherwise the statement might affect unrelated tests. mysql-test/t/lock_multi.test, Reap statement status

Remove per-project SAFEMALLOCs definitions, as they result in malloc/free mismatches.

BUG#49591, Fixed version string in SHOW CREATE TABLE to accomodate for column list partitioning and new function to_seconds

The test allowed random coincidence of connection ids for two concurrent
sessions performing CREATE/DROP temp tables.

Fixed with correcting the test. The sessions connection ids are not changed
from their defaults anymore.

                  
When compressed myisam files are opened, they are always memory mapped
sometimes causing memory swapping problems.

When we mmap the myisam compressed tables of size greater than the memory 
available, the kswapd0 process utilization is very high consuming 30-40% of 
the cpu. This happens only with linux kernels older than 2.6.9

With newer linux kernels, we don't have this problem of high cpu consumption
and this option may not be required.
 
The option 'myisam_mmap_size' is added to limit the amount of memory used for
memory mapping of myisam files. This option is not dynamic.

The default value on 32 bit system is 4294967295 bytes and on 64 bit system it
is 18446744073709547520 bytes.

Note: Testcase only tests the option variable. The actual bug has be to 
tested manually.

returns incorrect results with where

An outer join of a const table (outer) and a normal table
(inner) with GROUP BY on a field from the outer table would
optimize away GROUP BY, and thus trigger the optimization to
do away with a temporary table if grouping was performed on
columns from the const table, hence executing the query with
filesort without temporary table. But this should not be
done if there is a non-indexed access to the inner table,
since filesort does not handle joins. It expects either ref
access, range ditto or table scan. The join condition will
thus not be applied.

Fixed by always forcing execution with temporary table in
the case of ROLLUP with a query involving an outer join. This
is a slightly broader class of queries than need fixing, but
it is hard to ascertain the position of a ROLLUP field wrt
outer join with current query representation.

Problem: inserting a record we don't set unused null bits in the
record buffer if no default field values used.
That may lead to wrong live checksum calculation.

Fix: set unused null bits in the record buffer in such cases.

The bug is caused by a race condition between the 
INSERT DELAYED thread and the client thread's FLUSH TABLE.  The 
FLUSH TABLE does not guarantee (as is (wrongly) suggested in the 
test case) that the INSERT DELAYED is ever executed.  The 
execution of the test case will thus not be deterministic.

The fix has been to do a deterministic verification that both
threads are complete by checking the content of the table.

Calling push_warning/push_warning_printf with a level of
WARN_LEVEL_ERROR *is* a bug. We should either use my_error(),
or WARN_LEVEL_WARN.

Conflicts:
  - mysql-test/r/select.result
  - mysql-test/t/select.test
  - sql/item_cmpfunc.h
  - sql/sql_show.cc

to prepare for a tree parent alignment.
No code changes.

meaning a '/etc/init.d/mysql stop' would actually cause mysqld_safe to
relaunch mysqld rather than shut it down.