"Daniel Salama" <dsalama at user.net> wrote:

> Hi,
> 
> I'm experiencing a bit of a problem with a simple task I'm doing. I'm 
> trying to read a file and print something in the Transcript window 
> while reading the file. The problem I find is that while Squeak is 
> reading the file, the VM dedicates 100% of its processor time to that 
> task.
> On the same VM, I'm running Seaside, so while the VM is reading 
> the file, Seaside cannot render any pages. Any suggestions on how to 
> overcome this problem?

Work with processes is advanced stuff - I really cannot explain
that in 5 minutes. To give you a point to start, please try this:

reader := 
   [  | stream newLineChar line |
    stream := FileStream readOnlyFileNamed: filename.
    newLineChar := Character cr.
    [stream atEnd]
       whileFalse:
        [line := stream upTo: newLineChar.
         Transcript show: '.'.].
     stream close.
   ].

  reader forkAt: Processor userBackgroundPriority.
 
Rules:

1. To create a process, you have to encapsulate the
code in a block.
2. To start the process, you send that block one of the
messages  fork  or forkAt:
3. forkAt: allows you to assign a process priority, which
normally desired. The instance protocol of class
ProcessorScheduler contains methods to obtain process
priorities (in message category 'priority names')
Process is the sole instance of ProcessorScheduler
in your image, so you can obtain process priorities
from that object.
4. Processor userBackgroundPriority is a good choice
for file handling in the background.

When you try this example, you should find that
your interface is not locked, but you may notice
reduced responsiveness.


Some advices are very necessary:

1. Archivate a copy of your image and its changes
file before you begin to experiment with processes.
2. Do not try to save your image when processes that
you have created are still running.
3. You can ignore advice no. 2, but at a price:
It is often not possible to restart an image that was
saved while user created processes were still running.


Later 
Boris