The final fsync makes it 16 times slower

[davidfirst]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

I'm writing 6,700 files.
If I pass fsync: false to the options, it takes 9 seconds.
If I don't, it defaults to true, and it takes 152 seconds (!).

From the docs I see this:

If the fsync option is false, writeFile will skip the final fsync call.

Could you explain how important this final fsync call is? I'm considering to disable it.

Expected Behavior

I wish to have it faster, or understand whether it's safe to cancel the fsync.

Steps To Reproduce

try to write lots of files ( > 1000) to see the issue clearly.

Environment

• npm: 8.1.2
• Node: v16.13.2
• OS: Mac OS 12.6
• platform: Mac