If your goal is to read 50 items into an array on each pass of the loop:

while (!eof DATA) {
    local $/="\t";
    chomp(my @set = map {(eof) ? () : scalar(<DATA>)} 1..50);
    print "Set: ", join(',', @set), "\n";
}
[download]

Use whatever filehandle is appropriate.
Update: changed second eof to use "last file read" default form.