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Who sets RAILS_MAX_THREADS environment variable when running Puma or Passenger?

Who sets RAILS_MAX_THREADS environment variable when running Puma or Passenger on Linux?

How can I query the value of RAILS_MAX_THREADS from the linux command line while Puma or Passenger is running?

Solution

  • It's our responsibility to set RAILS_MAX_THREADS environment variable, that's why in most of the places it's written as

    <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>

    Means, if the constant is defined, then take that value, or use 5 by default. You can set it while running the deployment script, e.g.,

    export RAILS_MAX_THREADS=10

    Hope that helps!