MySQL Bugs: #39692: Falcon allocates SectorCache even if falcon_use

Bug #39692	Falcon allocates SectorCache even if falcon_use_sectorcache is OFF
Submitted:	26 Sep 2008 21:10	Modified:	8 Jan 2009 17:06
Reporter:	Kevin Lewis	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Falcon storage engine	Severity:	S3 (Non-critical)
Version:	6.0	OS:	Any
Assigned to:	Hakan Küçükyılmaz	CPU Architecture:	Any

Description:
Falcon allocates over 20 Mb of memory for the SectorCache even if falcon_use_sectorcache is OFF.

How to repeat:
1.  Start mysqld with the Falcon engine.

2. mysql> show variables like 'falcon_use_sectorcache';
+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| falcon_use_sectorcache | OFF   |
+------------------------+-------+

3. mysql> select * from INFORMATION_SCHEMA.FALCON_SYSTEM_MEMORY_DETAIL where FILE='SectorCache.cpp';
+-----------------+------+----------------+--------------+-----------------+---------------+
| FILE            | LINE | OBJECTS_IN_USE | SPACE_IN_USE | OBJECTS_DELETED | SPACE_DELETED |
+-----------------+------+----------------+--------------+-----------------+---------------+
| SectorCache.cpp |   37 |              1 |     20054040 |               0 |             0 |
| SectorCache.cpp |   39 |              1 |        37848 |               0 |             0 |
+-----------------+------+----------------+--------------+-----------------+---------------+

Suggested fix:
uSE  if (falcon_use_sectorcache)  before creating and deleting the sectore cache.

6.0.8-alpha-debug-log
[23:14] root@test>select file, line, space_in_use from information_schema.falcon_system_memory_detail order by file  desc;
+------------------------+------+--------------+
| file                   | line | space_in_use |
+------------------------+------+--------------+
| Values.cpp             |   62 |          272 |
| Value.cpp              |   94 |           88 |
...
...
...

| SectorCache.cpp        |   39 |        58600 |
| SectorCache.cpp        |   37 |     20054048 |

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/54601

2832 Hakan Kuecuekyilmaz	2008-09-27
      Fix for Bug#39692.

A note has been added to the 6.0.8 changelog: 

Memory would be allocated for the Falcon sector cache even if the cache had been disabled (falcon_use_sectorcache).