Unicorn on shared apps platform

Amol Dev devamol at yahoo.com
Tue Feb 26 15:08:11 UTC 2013


We are hosting multiple Rails applications on same server and using Passenger + Apache. I can see Unicorn be useful for seamless deploys, few questions running it on Rails platform with 50+ rails apps:

a) How does unicorn scale if app is known to be slow with long running quieres to database? Is there a way to a have master worker spin up new workers aka dynamic workers?

b) Can Unicorn be configured to start with zero worker and master spawning first worker as first request comes in? Very useful to stack multiple apps that are not used all the time. 

From (a) and (b) I guess I am asking if worker_processes can scale from 0 to X if database is slow or if there is no need to have workers running if the application is not gonna be used (in Freetrails and Sandboxes)

c) Unicorn for zero lost connection (no downtime during deploy and changes) needs new workers spinned up before old workers are sent USR2 signal, does this not mean that one has to provision double memory for servers?


--Amit


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