Vista - Use "lock" in three methods to prevent shared-memory corruption

I have an arraylist used in three separate methods.

In method #1 (event method), some items are removed from the arraylist
if certain conditions are met;

In method #2 (event method), properties of some items are modified if
certain conditions are met;

In method #3, it loops through each item in the arraylist without
changing any item on the arraylist or removing any item from the
arraylist. In other words, this is "read-only" type of operation.

Since both #1 and #2 are event methods and may happen anytime, there's
a chance that #1, #2, and #3 all happen at the same time, then I'll
run into a memory issue when one process is modifying the arraylist,
other process(es) are accessing the arraylist.

I plan to use "lock" in all of these three methods. I have questions:

1) I know "lock" is typically used in two methods. Will there be an
issue if "lock" is used in more than two methods?

2) If I use "lock" in #1 and #2, will locking the process cause the
associated **event objects** to expire since they are dynamic in
nature and only live for a very short period of time?

I would appreciate any input!

Curious wrote:No. Locking ensures that only one piece of code can hold the lock at any one
time. It doesn't matter how many threads are trying that simultaneously
(though obviously performance suffers greatly if many threads are contending
for a single lock, but that's another matter altogether).
What event objects? Neither event handling nor locking intrinsically create
objects.

--
J.

Are you using multiple threads? You don't need to use locking unless
you have multiple threads.

If you are using VS2005 or later you should consider using the generic
List(Of T) rather than ArrayList.

On Wed, 30 Jul 2008 09:04:16 -0700 (PDT), Curious
<fir5tsight@xxxxxx> wrote:

Hi Jack,

Thanks for asking this!

#1 and #2 are on the same main thread, while #3 is on a separate timer
thread that runs every 15 seconds.

#1 and #2 are events and may happen at anytime. What happens if #1 and
#2 happen at the same time? Are they serizlized or do they step on
each other's feet?

Hi Andrew,

Thanks for the input!

FYI, I "lock" the section of the code in all of the three methods that
use the arraylist.

Events on the same thread do not interrupt each other.

If the timer is a System.Windows.Form.Timer then it runs on the main
UI thread and will not interrupt the other events.

On Thu, 31 Jul 2008 06:17:50 -0700 (PDT), Curious
<fir5tsight@xxxxxx> wrote: