App Engine cold starts suddenly very slow >minutes

[koen12344]

I noticed my App Engine cold starts suddenly became very slow, without any changes being made to the app itself. Cold starts went from taking a few hundred milliseconds, to taking up to a few minutes to start an instance.

I redeployed the app and that made the issue go away for a few days, but now its back and worse than before.

It's is a very simple PHP 7.4 app using Slim framework.

I don't really see any clues in the logs, just the initial request, and then -after up to a few minutes- the first [start] log entry. Followup requests on the same instance are handled within a few milliseconds.

Anyone have any idea what to look for or what the issue could be?

I know about warming requests and min-instances, but cold starts only used to take maybe up to a second. This app handles asynchronous requests from my front-end app so slow cold starts aren't really an issue, but this is excessive!

runtime: php74
handlers:
  - url: /.*
    script: auto
    secure: always

[gsuceveanu]

Hello, 

As this is an issue specific to your App Engine service, a proper investigation needs more data, including private data such as project ID. This is difficult to handle in a publicly visible thread as this one. You may consider opening a support case to that purpose, which enjoys restricted visibility, and suitable for handling confidential data. 

You are right about warming requests and the like. Related valuable information can be found on the "Best practices for App Engine startup time" documentation page.