Immediate vs. Deferred Writing

• By default, changes to the array are propagated to the file immediately

  • This is called immediate writing

• In some cases, this will be intolerably slow:

 for (@FILE) {
 s/^/>> /;
 }

• This modifies record 0, rewriting 0 .. 1000

  • Then it modifies record 1, rewriting 1 .. 1000

  • Then it modifies record 2, rewriting 2 .. 1000

  • This is intolerably slow