Decoding and encoding CSV is extremely slow about csv HOT 2 CLOSED

I've done extensive file io testing with Dart and found that Dart's async transformers and raw IO bandwidth are actually a huge bottleneck. See dart-lang/sdk#43534 .

So I feel that the slowness may not be caused by the library itself.

The IO performance problem seems to be caused by many separate read operations, which have operating system overhead (on windows at least), and the fact that every async task is first scheduled and then executed at the next tick.

Sync operations can be twice as fast.

I haven't checked if this package can be used synchronously, but if you can I'd recommend:

• read your entire CSV file at once (dart has a limit of 1GB), or read it into chunks as large as possible
• process the data synchronously

from csv.

Well, turns out my assumption was wrong. It indeed is slow. Please see PR #36 . This solves the encoding performance problem.

from csv.