Investigate and resolve blazor load error

[pbiggar]

When loading blazor, many of the files it needs will not load in the browser. The browser stops being able to make a connection to the server. This only happens in production. It is most commonly reproduced by loading and then doing another load from a clean cache.

I managed to reproduce the error:

Uncaught exception Blazor worker failure TypeError: Failed to fetch
    at loadResource (blob:https://darklang.com/dacea6f8-981c-4a6a-9522-f78faeed6aeb:738:24)
    at blob:https://darklang.com/dacea6f8-981c-4a6a-9522-f78faeed6aeb:732:11
    at Array.map (<anonymous>)
    at Object.loadResources (blob:https://darklang.com/dacea6f8-981c-4a6a-9522-f78faeed6aeb:731:39)
    at createEmscriptenModuleInstance (blob:https://darklang.com/dacea6f8-981c-4a6a-9522-f78faeed6aeb:220:52)
    at blob:https://darklang.com/dacea6f8-981c-4a6a-9522-f78faeed6aeb:772:25 undefined undefined undefined
e.<computed> @ appsupport-0aab008024f907c251bfe9927856eeebed075655f5139be469f7af1ceaf66459.js:179373

And it seems to happen when part of the load time's out:

Unclear why these loads time out, but this happens in about 1/4 of the times I refresh.

Originally posted by @pbiggar in #3254 (comment)

[pbiggar]

Some investigation:

• I can trigger this by loading once, and then clicking "Empty cache and hard reload"
• the error in Chrome is ERR_CONNECTION_CLOSED. The files being loaded are "pending" for 30 seconds, and then error/timeout
• if one fails, typically 50 others do as well
• it is not always the same files that fail to load each time, though it often is
• ordering matters: the first ~40 all succeed, then progressively more likely to fail, then the last ~30 all fail
• taking the failing urls and fetching them via curl succeeds
• the items being requested are uploaded to the bucket and configured properly
• no observable differences between things that succeed and things that fail, at the bucket level
• the load balancer does not have any logs for these requests
• all requests (success and failure) to the static assets load balancer are "h3" (http3)
• there is no consistency to the name, url length, content-type, or file extension of the files that fail and succeed
• this happens with all extensions disabled in incognito mode

ERR_CONNECTION_CLOSED means it wasn't able to make a connection:

• chrome has a connection limit?
• ddos protection at google?
• my os/router/isp/other doesn't like that many connections of that size/content-type/etc?
• a chrome extension is preventing this from working? tested

[pbiggar]

I don't have any clues here so I'll see who I can ask.

[pbiggar]

Using correct content-types didn't change anything.

[pbiggar]

• ask blazor people about it
• ask google cloud support about it
• try a different browser

[pbiggar]

Google cloud says it's not them.

[StachuDotNet]

Given I could eventually replicate this on my laptop, maybe we should figure out what's consistent between my laptop and your computer, and not consistent with my desktop where I can't replicate.

Both my desktop and laptop are Ubuntu with Chrome on WiFi. The initial differences that come to mind would be drivers, chrome versions, extensions loaded, internet config settings, Ubuntu versions (desktop is 21.10 - maybe laptop is 21.04?) or underlying linux versions.

What variables would be worth looking at, if that seems a useful path?

[pbiggar]

You're not going to believe this but I just upgraded to Chrome 99 and I can't replicate this anymore!

[StachuDotNet]

You're not going to believe this but I just upgraded to Chrome 99 and I can't replicate this anymore!

LOL that's amazing. Not sure how to feel about this. I guess we're OK? Would love to find the issue in their tracker.

[pbiggar]

This feels like it: https://bugs.chromium.org/p/chromium/issues/detail?id=1286445

[pbiggar]

I upgraded from Chrome 97 to Chrome 99 which includes that fix.