Re: [MacPerl] Read Speed

[mark@cheers.jsc.nasa.gov (Mark Manning/Muniz Eng.)]

According to Jon S. Jaques:
> 
> On my PowerBook 540 w/12mb ram, I get an 'Out of memory!' error on the
> following, while reading in a 5mb ASCII file:
> 
> open(IN,  "$hostname:Desktop Folder:allfiles.txt");
> open(OUT, ">$hostname:Desktop Folder:allfiles2.txt");
> 
> @LINES = <IN>;
> print OUT join(' ', @LINES);
> 
> close IN;
> close OUT;
> 
> Using the afore mentioned read methods, MacPerl duplicated the file in 20
> seconds.

This is probably because if your read in a 5mb file, you've
actually got 5.5mb of information (with string and array
handling overhead).  Then the JOIN command forces MacPerl
to create a new 5mb string.  This give you somewhere around
11mb being used by MacPerl.  System 7.0 and later use a
minimum of 2mb to run (mine uses 12mb).  11mb + 2mb >
12mb.  Your PB crashes and burns.

Quit trying to do everything in memory at one time.
Systems with small memories should work on one or two lines
of information at a time.  This keeps your overhead down.
So to rewrite your program:

	open( IN, "$hostname:Desktop Folder:allfiles.txt");
	open(OUT, ">$hostname:Desktop Folder:allfiles2.txt");

	while( <IN> ){
		chomp;
		print $_;
		}

	print "\n";
	close IN;
	close OUT;

This does the same thing, but on a single line at a time basis.

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