Patternless 500 crash that logs 204

[Alberto Cantú Gómez]

As Steve Jobs said in this video

https://www.youtube.com/watch?v=dxNQebY-Qdw

"Don't be afraid to ask for help".

Hello dev community, our team have been developing this RESTful API with Slim PHP as router and Propel ORM with MySQL, deploying it as a service in Google App Engine with this app.yaml config

service: api
runtime: php55
api_version: 1
threadsafe: yes

instance_class: F1
automatic_scaling:
  min_idle_instances: automatic
  max_idle_instances: automatic
  min_pending_latency: automatic
  max_pending_latency: automatic

skip_files:
- ^vendor/(.*/)+[Tt]ests/.*$
- ^\.(.*)

handlers:
- url: .*
script: app.php

to be consumed by an Ember.js web app, through all the development we've been receiving strange patternless server crashes 500s, more precisely:

500 Server Error Error: Server Error The server encountered an error and could not complete your request. Please try again in 30 seconds.

with App Engine Log.

A problem was encountered with the process that handled this request, causing it to exit. This is likely to cause a new process to be used for the next request to your application. (Error code 204)

in random endpoints, that otherwise works fine 99% of the time, we, of course, don't feel like going into production with these random crashes.

What we have tried:

1. Checking whether the MySQL max_connections is being reached because we open and close a connection every request.
   
2. Upgrading our instances from F1 for the sake of testing to F4_1G to tackle the possibility that we might be running out of memory.
   
3. Stress tests in localhost with dev_appserver.py, (we don't get any crashes here)
   
4. Try catch the whole Slim App for debugging (which it actually never catches the exception so it leads us to think it has really something to do with Google App Engine)
   

Sincerely, thanks in advance.

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[Kenworth (Google Cloud Platform)]

A thread like this is off-topic for Google Groups, and you were right in opening a Public Issue Tracker for this case. This forum isn't meant for specific 1-on-1 technical issues, but for general discussion of the platform and its services. As such, I recommend users having the same concerns to provide their feedback on the issue tracker so that proper attention will be given to it.