On Sun, Aug 16, 2009 at 10:39 AM, Alex Chaffee<ale...@gmail.com> wrote: > During the few seconds the restart is happening, what happens to > incoming HTTP requests? Are they queued or do they fail? If the > latter, where's the error page and can we change it? > > And what's the timing like for applying the change to multiple dynos? > Is it possible that one dyno is still running the old code while > another is running the new code?
Requests will always be going to one and only one revision of the code at a time. The sequence is like this: 1. You git push, which compiles a slug. 2. If successful, the slug is distributed to our dyno grid and dynos are started for the new slug. But no traffic is being sent to them yet - the routing mesh is routing all traffic to the dynos running the old slug. 3. Once all the new dynos are up and ready to receive connections, the routing mesh updates its routing table. Existing requests will complete on the old dynos, any new requests will be sent to the new ones. In summary, the switch is instantaneous and seamless, with no period of error pages or requests being routed to the wrong dyno. You can test this yourself by running a simple load test during a deploy. Something like: $ ab -c 1 -n 50 http://myapp.heroku.com/ | egrep '^(Complete|Failed)' & $ git push heroku When I ran this I got the following output (after all the git push / heroku slug compile messages): Complete requests: 50 Failed requests: 0 Adam --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Heroku" group. To post to this group, send email to heroku@googlegroups.com To unsubscribe from this group, send email to heroku+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/heroku?hl=en -~----------~----~----~----~------~----~------~--~---
