Subj : Re: Challenge: Multithreading & Synchronization
To   : comp.programming.threads
From : Giancarlo Niccolai
Date : Sat May 21 2005 02:34 pm

Maciej Sobczak wrote:

> Uenal Mutlu wrote:
> 
>>>The terminal?
>> 
>> Of course:
>> Question: Is in your application the terminal shared by multiple threads?
>> Answer: YES
>> Then: make the terminal lockable
> 
> No. I have specifically used the puts() function to show you that there
> are cases where there might be no "object" which you can "physically"
> grab and wrap. This example was extremely simple, yet you have rejected
> to see the point and have converted the example to use cout - just to
> fit it to your broken idea?
> 
> Let's say there is no cout, but instead the "print" function:
> 
> print("I'm doing something");

More. The terminal operation may be a LONG operation. If a terminal get
disconnected while accessed, it may even be a kind of neverending
operation. Cancelation problem apart (which Mutlu seems not to know as he
speaks only about windows primitive), that may kill your thread while
holding the terminal mutex, it is not correct to lock an OPERATION complex
as a terminal output to secure the access to terminal OBJECT. Locking an
operation (print) to protect an object (terminal) is wrong.

You must find another way to output to the terminal in a way that won't be
interfered by other threads. The way exists, and it's simple, just look a
little further...

The solution applies to all long operations applied to complex object, as
database updates. 

Giancarlo.

.