pub get became very slow

[huanghui1998hhh]

Here's the flutter pub get -v output.

pub_get.log

Observed timings

• Total: ~408.79s
• Version solving: ~2.01s
• Root project phase before first Got dependencies!: ~380.01s
• Metadata HTTP requests count: 364
• Sum of HTTP request durations: ~370.37s
• Median request latency: ~0.91s
• p95: ~1.40s
• p99: ~3.16s

Expected behavior

dart pub get should complete significantly faster for already-cached packages / lockfile-stable graphs, and should not require so much wall-clock time in metadata lookups.

Environment

• Dart (from Flutter SDK): Pub 3.11.5 (from verbose log)
• OS: macOS (arm64)
• Command path: flutter pub get --example -> dart pub get -v

[huanghui1998hhh]

I suspect there may be an unintended cache bypass in HostedSource._getAdvisories():

pub/lib/src/source/hosted.dart

Lines 795 to 796 in d5fca3a

	final advisoriesUpdated =
	(await status(id.toRef(), id.version, cache)).advisoriesUpdated;

@sigurdm @kevmoo Anyone help?

[rs5173]

+1

[jonasfj]

Median request latency: ~0.91s

API end-points used by pub get should all be served from GCS through Cloud CDN. Granted the GCS bucket isn't replicated around the world, and that is an optimization we could do.

But such high latency is that something you can reproduce outside the pub client too?

Given that your location is "Mars", one could argue that 900ms latency is pretty good 😄🙈

But ~0.9s seems pretty slow? where are you located? What does traceroute pub.dev say?
Is this the same for google.com, etc. Are you both through-put limited and latency limited? would increasing concurrency help?

Better caching might help, but we do want to fetch meta-data regularly to surface advisories, and other meta-data. But we could potentially be less aggressive about it :D

A workaround for the caching issue is just to use --offline.

[jonasfj]

Also: is this behavior new? related to a new Dart SDK or just something changed on the service?

[huanghui1998hhh]

My geographic location may have some impact🤣

But the more important issue is that the expected cache does not seem to be working, since every pub get ends up fetching _getAdvisories again.

@jonasfj

[huanghui1998hhh]

Almost all Flutter-related commands depend on pub get. Some of them can be skipped with --no-pub, but many others, such as commands launched through the Dart/Flutter MCP tooling, do not let me control the arguments. Having multiple extremely slow pub get runs that also fail to use the cache nearly brings my machine to a halt. 😭

[jonasfj]

does it re-fetch advisory stuff even if the cache is 5min old.

[huanghui1998hhh]

does it re-fetch advisory stuff even if the cache is 5min old.

Yes. Everytime.

And I traced it down to this part.
It looks like an accidental cache bypass caused by an omitted maxAge, rather than an intentional freshness guarantee.

pub/lib/src/source/hosted.dart

Lines 795 to 796 in d5fca3a

	final advisoriesUpdated =
	(await status(id.toRef(), id.version, cache)).advisoriesUpdated;

[sigurdm]

So there is indeed problems in the client. We will fix those.

But the reason you saw a sudden change is an update in the server. We will revert that. The deployment will most likely happen tomorrow.

Sorry for the inconvenience

[huanghui1998hhh]

@sigurdm Thanks~