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Hi all,

We see a lot of requests to our state backend when doing a `pulumi up` without any changes. Is this expected behavior?
I would expect Pulumi to only make a snapshot if something changes, is that not the case?

We have found the <https://www.pulumi.com/blog/pulumi-release-notes-80/#skip-checkpoints-experimental-flag|skip-checkpoints flag>, but would like to better understand the underlying issue (if any) before we enable it.
Our large >3000 resource stacks are currently taking a very long time (>40min) to `up` even if there are little or no changes and are looking to speed it up.

If you run with debug logs `--logtostderr -v9` you might see some "SnapshotManager: mustWrite() true because" lines which will tell you why they system still thought it had to do a write even though the inputs hadn't changed enough to trigger a provider update.
Give that a try, we can see if that's whats causing the writes.

Sweet! Sounds good, will do. Just to preemptively clarify; it's not expected to see snapshot writes w/o actual changes?

It's not expected but we've had issues in the past that triggered it

When doing a `pulumi up` on a test stack I'm seeing:
```mustWrite() false```
on all resources when parsing the logs.

When doing `pulumi up --refresh` I see:
```Resources:
    39 unchanged```
in stdout
And a lot of:
```SnapshotManager: mustWrite() true because of Inputs```
The logs are a bit hard to parse. I have added `-p 1` in the hopes log lines wouldn't interleave, but I'm still having trouble seeing where operations start and end.
Any pointers on how to further debug, and/or what to look at are much appreciated : )

I am looking at the `.Diff()` lines and am seeing that the `.oldInputs`  have 2 entries with `__defaults={[]}` and the `.newInputs` have 3. Not sure if that could have anything to do with the issue.

can you raise an issue about this, we'll need to get that fixed across a number of repos I think

Thanks. Issue created here:
<https://github.com/pulumi/pulumi/issues/19715>

Do you think the number of `__defaults={[]}`  entries is indeed the culprit?

yeh probably, the engine isn't smart enough to know what inputs are meaningless vs important, so we depend on the providers to give good data here

Makes sense. If any other info is needed please let me know, I'll be monitoring the GH issue. Thanks for the quick response, much appreciated! :cute-pulumi-heart: