dart:io sync vs async file operations

问题

There are a number of sync and async operations for files in dart:io:

file.deleteSync() and file.delete()
file.readAsStringSync() and file.readAsString()
file.writeAsBytesSync(bytes) and file.writeAsBytes(bytes)
and many, many more.

What are the considerations that I should keep in mind when choosing between the sync and async options? I seem to recall seeing somewhere that the sync option is faster if you have to wait for it to finish anyway (await file.delete() for example). But I can't remember where I saw that or if it is true.

Is there any difference between this method:

Future deleteFile(File file) async {
  await file.delete();
  print('deleted');
}

and this method:

Future deleteFile(File file) async {
  file.deleteSync();
  print('deleted');
}

回答1:

Let me try to summarize an answer based on the comments to my question. Correct me where I'm wrong.

Running code in an async method doesn't make it run on another thread.
Dart is a single threaded system.
Code gets run on an event loop.
Performing long running synchronous tasks will block the system whether it is in an async method or not.
An isolate is a single thread.
If you want to run tasks on another thread then you need to run it on another isolate.
Starting another isolate is called spawning the isolate.
There are a few options for running tasks on another isolate including compute and IsolateChannel and writing your own isolate communication code.
For File IO, the synchronous versions are faster than the asynchronous versions.
For heavy File IO, prefer the asynchronous version because they work on a separate thread.
For light File IO (like file.exists()?), using the synchronous version is an option since it is likely to be fast.

dart:io sync vs async file operations

问题

回答1:

Further reading