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I am using rails 3.2 + unicorn + postgres DB and i have a question - how does unicorn handle DB connections ?

How I understand:

  1. unicorn master process forks X child process.
  2. each child process setup DB connection– close in before_fork, establish connection in after_fork.
  3. we use connection per process(if we use rails DB connection pooling, we create Y(from database.yml) DB connections per process) - i.e. If process is working(It always works until we not kill it) we keep connection opened and every web request use the same connection(that was opened in after_fork).
  4. opened connections will be shown in postgres(or any other DB) as idle or active.

Is it correct or I missed something ?

Alexander Randa
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Dzmitry
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2 Answers2

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Yes you are right. If you set "worker_processes 5" in unicorn.conf, and "pool: 4" in database.yml, will be create d 20 connections to database.

Alexander Randa
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i wrote to Eric Wong he is founder of unicorn gem, he confirmed that it's correct.

Dzmitry
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