[AccessD] Tracking down memory leak

Don,

<<So, now I'm more confused than when I started.  How exactly does one
detect memory leak, and once detected, how to find its source?>>

  A "memory leak" stems from a process that allocates memory for a purpose,
but then doesn't give it back.  From task manager, check the specific task
instance and see if the memory it's using grows.  If so and the app is doing
the same thing over and over, then you have a leak.

  From what you describe below, it doesn't sound like you have a leak.  It's
not abnormal to see memory (and handles) grow and shrink while an app is
running.

  Exactly what is the problem your having?
Jim.

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of McGillivray, Don
[IT]
Sent: Thursday, January 22, 2009 1:39 PM
To: Access Developers discussion and problem solving
Subject: [AccessD] Tracking down memory leak

Hi, All

I'm looking for guidance on identifying the source of a memory leak in an
application.  I've already gone through my code to ensure that each "Set
ObjVariable =  . . . " statement is accompanied by a "Set ObjVariable =
Nothing" statement.  All my procedures use error handling, and are forced to
exit through a substructure that contains the proc's "Set ObjVariable =
Nothing" statements, ensuring that the object variables are set to nothing
even when an error occurs.

As the app runs, both memory usage and the handle count slowly creep up over
time - the handle count faster than the memory usage.

I did a simple experiment by monitoring handle usage while opening and
closing a single table in a database several times.  I noticed that at first
the handle usage was variable, but that after several repetitions it more or
less stabilized.  Something like this:

Rep             State           Handles
=================================
0               Initial 195
1               Open            203
1               Closed  199
2               Open            203
2               Closed  200
3               Open            202
3               Closed  200
4               Open            201
4               Closed  200
5               Open            210
5               Closed  204
6               Open            207
6               Closed  204
7               Open            206
7               Closed  201
8               Open            204
8               Closed  201
9               Open            204
9               Closed  201

For grins, I left the db open and idle overnight.  When I checked this
morning, its memory usage had gone from 20.7 MB to 3.7 MB.  Upon opening the
table, the usage went to 7.8 MB and stayed around there after several
open/close repetitions.

So, now I'm more confused than when I started.  How exactly does one detect
memory leak, and once detected, how to find its source?

Anybody out there with nothing better to do than to educate my weak brain?

Don

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