Daemons do not get restarted?

daemons, ruby

Solution

I was able to reproduce the behavior. It is not anything you are doing wrong; it is the way the `daemons gem` behaves.

Going through the code for the daemons gem, turns out the `:multiple` option doesn't work well with the `:monitor` option.

The `:monitor` option works only when the daemon is run in single mode.

I have created a bug report on the daemons project page referencing this question as the source.

More info about the reproduction of the issue:

Multiple daemon processes are created when `:multiple => true`. Each process has its own pid file in the format of `<scriptname>.rb<number>.pid`.

However, only one monitor process is created (with a single `<scriptname>.rb_monitor.pid` file.)

Here are the list of processes started when I start the daemon process 3 times:

$ ps -fe | grep my_server
  501  1758     1   0 12:25PM ??         0:00.63 my_server.rb  
  501  1759     1   0 12:25PM ??         0:00.43 my_server.rb_monitor  
  501  1764     1   0 12:25PM ??         0:00.54 my_server.rb  
  501  1834     1   0 12:51PM ??         0:00.31 my_server.rb

The files in the pid/log folder:

$ ls /tmp/daemons-2013-01-25/
my_server.rb.log                my_server.rb1.pid               my_server.rb_monitor.pid
my_server.rb0.pid               my_server.rb2.pid

Problem

I am trying to run the same script in multiple daemons. `myapp.rb` looks like this: ``` loop do sleep 5 1 / 0 # crash it end ``` my `myapp_controller.rb`: ``` require 'rubygems' require 'daemons' options = { :log_output => true, :backtrace => true, :monitor => true, :multiple => true, :log_dir => '/mnt/log/', :hard_exit => true } Daemons.run(File.join(File.dirname(__FILE__), 'myapp.rb'), options) ``` When I run `ruby myapp_controller.rb start` several times in a row, it creates that many daemons, as I expect. But, after a while, due to an error in `myapp.rb` the daemons crash and the monitor restarts just one and not all. So I end up with a single running daemon. Why? What am I doing wrong?

Original source