Speed up the starting of datanode

[WenyXu]

What type of enhancement is this?

User experience

What does the enhancement do?

Opening a region in mito2 still waits for network returns in a &mut self function, which is super expensive.(If opening a region requires 50ms, this worker only has 20qps)

greptimedb/src/mito2/src/worker/handle_open.rs

Lines 66 to 76 in 4fcda27

	let region = RegionOpener::new(
	region_id,
	&request.region_dir,
	self.memtable_builder.clone(),
	self.object_store_manager.clone(),
	self.scheduler.clone(),
	)
	.options(request.options)
	.cache(Some(self.cache_manager.clone()))
	.open(&self.config, &self.wal)
	.await?;

Implementation challenges

No response

[tisonkun]

Is this issue still relevant? It seems quite vague what we can improve.

[tisonkun]

Closed unless we have more concrete stuff to improve.