[DUG] Threads again

[Ross Levis]

Ahh.  I thought I had heard of some way of doing this.  I actually need to
use InterlockedExchangeAdd as it's not 1 that it is incremented by, but I've
implemented this and it works.

 

Many thanks,

Ross.

 

From: delphi-bounces at delphi.org.nz [mailto:delphi-bounces at delphi.org.nz] On
Behalf Of Myles Penlington
Sent: Tuesday, 17 July 2007 16:35
To: NZ Borland Developers Group - Delphi List
Subject: RE: [DUG] Threads again

 

Yes you need something. 

You can use InterlockedIncrement and InterlockedDecrement instead of
Inc/Dec.

 

Myles.

 

From: delphi-bounces at delphi.org.nz [mailto:delphi-bounces at delphi.org.nz] On
Behalf Of Ross Levis
Sent: Tuesday, 17 July 2007 04:02
To: 'NZ Borland Developers Group - Delphi List'
Subject: [DUG] Threads again

 

I'm trying to avoid using a critical section due to time overhead.  In one
thread I have a global integer incrementing roughly every 20 milliseconds
using Inc(x,y).  In another thread I have the same integer decreasing using
Dec(x,y) at about the same speed.

 

Is it critical to have these in a critical section?  I've been testing it
here for a few days continuously and it appears to work fine without one.

 

Even with a dual processor and each thread running on a separate processor,
is it possible for one memory location to be written precisely at the same
time?  It doesn't matter which occurs first or in which order.

 

Cheers,

Ross.

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