From: Shea Martin <null@...0>
Date: 2005-10-13T23:12:04+09:00
Subject: Re: threading in win32

Ara.T.Howard wrote:
> On Thu, 13 Oct 2005, Shea Martin wrote:
> 
>> I have a TK app.  On a button presses, I call a windows copy command 
>> which can take up to 10 minutes to run. In order to not freeze the 
>> GUI, so that the gui can be doing other stuff, I launch the command in 
>> a thread.
>>
>> Running the command with system, does not let me get the output of the 
>> command, thought it does not lock gui up at all.  So, I tried two 
>> other versions.  I had the most success with version 3. I believe 
>> version 3 is what the TkTextIo example uses in ruby 1.8.3. See below.
>>
>> # callback for tk button press
>> def buttonPress
>>  Thread.new do
>>    Button.state( "disable" );
>>    runCommand( "copy /Y bigfile1 dest1" );
>>    runCommand( "copy /Y bigfile2 dest2" );
>>    runCommand( "copy /Y bigfile3 dest3" );
>>    Button.state( "active" );
>>  end
>> end
>>
>> #version 1
>> def runCommand( cmd )
>>  system( cmd )
>> end
>>
>> #version 2
>> def runCommand( cmd )
>>  IO.popen( cmd ) do | cmd_out |
>>    cmd_out.each_line do | line |
>>      MyTextArea.insert( 'end', line, 'normal' )
>>    end
>>  end
>> end
>>
>> #version 3
>> def runCommand( cmd )
>>  cmd_pipe = IO.popen( cmd )
>>  t = Thread.new { cmd_pipe.each{ | line | addText( line ) } }
>>  t.join
>> end
>>
>> Only version 1 allows teh gui to remain responsive.  Unfortunately it 
>> does not capture the output of the copy command.  I would like to 
>> something with a fork, though win32 ruby does not seem to support it.
>>
>> Any ideas.
> 
> 
> i think reading from pipes should not block the whole process in 
> windows, at
> least this works fine on my win system:
> 
>   Thread::abort_on_exception = true
>   t = Thread::new{ IO::popen("tree c:").read }
>   (4 << 2).times{ p 42; sleep 0.42 }
>   puts t.value
> 
> does it work on yours?
> 
> perhaps you need something like
> 
>   #version 4
>   def runCommand( cmd )
>     Thread::new do
>       IO::popen("#{ cmd 2>&1 }"){|pipe| pipe.each{|line| addText line}}
>     end
>   end
> 
> which is to say spawn the thread and let it go.  you'll need to prevent two
> commands being run at once too...
> 
> hth.
> 
> -a


Everything works for fine when cmd = "tree C:\ /F". The text area is 
updating, with gobs of output, and I can still use the scroll bars, etc.
But when cmd = "copy /Y 1GB_FILE.BIG BAK_1GB_FILE.BIG", the problem 
occurrs. Scrollbars don't work, etc. I guess this must be a windows 
limitation.  This is a 3.2 GHz machine with H/T enabled, and 2GB of RAM, 
so I don't think it is a h/w limitation (though it is only IDE).  Also, 
if I use the system( cmd ), version it does not happen, and it does not 
happen if I just copy the file (manually) while running the gui.  I'll 
have to try it when I get home tonight on my solaris and linux boxen.

What happens when you try cmd = "copy /Y 1GB_FILE.BIG BAK_1GB_FILE.BIG"?

~S