Open on GitHub and Blame is extremely slow

[Neme12]

When I click GitHub -> Blame or Open on GitHub, it takes more than 10 minutes until the website pops up in my browser.

[Neme12]

It's possible this has to do with the size of the repo. I tried to do this on small repos and it appears instantly. But if I try on dotnet/roslyn, it takes a very long time which makes it completely unusable. Repro:
1. clone https://github.com/dotnet/roslyn and open Roslyn.sln
2. open any file and use Open on GitHub or Blame

[Neme12]

This code looks highly suspicious to me:

VisualStudio/src/GitHub.Exports/Services/GitService.cs

Lines 106 to 113 in b9939d2

	var remoteHeads = repo.Refs.Where(r => r.IsRemoteTrackingBranch).ToList();
	foreach (var c in repo.Commits)
	{
	if (repo.Refs.ReachableFrom(remoteHeads, new[] { c }).Any())
	{
	return c.Sha;
	}
	}

[Neme12]

Ok I can't repro this anymore... But I remember this happening to me almost every time I tried to use this feature. Maybe I need to have some unpushed commits...

[meaghanlewis]

Hi @Neme12 I'm not able to repro the behavior you initially mentioned either. I'm happy to leave this issue open for a bit. If you experience this lag again please let us know.

[Neme12]

Thanks. Sorry for posting without a repro or more info, it was just a bit frustrating. I don't use the product regularly (only when contributing) but I've experienced this consistently when I tried to use this feature so I thought it would be easy to reproduce. I'll try to find a minimal repro.

[Neme12]

After cloning it is indeed fast, but if I simply create a new branch with:
git checkout -b newBranch that increases the time to over 1 minute.

(This is still far from the 10 minutes I experienced earlier, I'll try to experiment more)

If I checkout master again, it's fast again.

[Neme12]

If I create a new commit (with one-line change), that increases the time by 2 more minutes.

[Neme12]

An empty commit works too, and it looks like every commit adds almost 2 minutes.

Here's a repro:
After cloning https://github.com/dotnet/roslyn, open any file and click GitHub->Open on GitHub on any line. It's nice and fast. Then run following commands:

git checkout -b newBranch
git commit --allow-empty -m "hello 1"
git commit --allow-empty -m "hello 2"
git commit --allow-empty -m "hello 3"
git commit --allow-empty -m "hello 4"
git commit --allow-empty -m "hello 5"

After doing this and trying to use Open on GitHub again, it took 9 minutes 20 seconds for the website to popup.

[Neme12]

@meaghanlewis Is this repro good? I'm sorry it requires opening dotnet/roslyn but I'm not able to reproduce this with a smaller repo. I hope this helps. Thank you very much for investigating this.

[meaghanlewis]

Hi @Neme12 thanks for digging into this more! No worries about reporting an issue when you don't have all the details.

I tried the repro steps you mentioned to check out a branch and create some commits using the roslyn repository. I do notice it's a bit slower, but selecting either Open on GitHub or Blame doesn't take more than 15 seconds to open the browser for me.

[Neme12]

I'm sorry you are right... I just finished deleting my repo and then cloning from scratch (making sure it's the original repo, not my fork) and I do only see a delay of about 40 seconds... 😕 I don't know what the 10 minutes could have been caused by... the fact it's a fork? having more custom branches? more remotes? having something in stash? I'll have to investigate more later...