monitoring ruby app memory usage with passenger-recycler (was: Cannot require library for passenger in ruby)

[Karli Sjöberg]

On Tue, 2018-02-20 at 21:31 +0000, Marcin Cieslak wrote:
> On Mon, 19 Feb 2018, Karli Sjöberg wrote:
> 
> > > What is the tool you are trying to deploy? foreman_maintain?
> 
> Sorry, I was too quick. This foreman_main is used to download/update
> foreman
> from RedHat Satellite servers, which is not what you want.

Well, I want the "foreman_maintain" package, which includes "passenger-
recycler", so I guess I do want it :)

> 
> However, the passenger-recycler script is a standalone script which
> could possibly used with this little fix:

Ooh, awesome! Yeah, should´ve figured since it´s only at 0.1.3 :)

> 
> https://github.com/theforeman/foreman_maintain/pull/143
> 
> To apply this, please add files/patch-bin_passenger-recycler in the
> port I've sent before:
> 
> --- bin/passenger-recycler.orig 2018-02-20 21:09:18 UTC
> +++ bin/passenger-recycler
> @@ -41,10 +41,10 @@ def process_status?(pid)
>  end
>  
>  require 'phusion_passenger'
> +PhusionPassenger.locate_directories
>  require 'phusion_passenger/platform_info'
>  require 'phusion_passenger/platform_info/ruby'
>  require 'phusion_passenger/admin_tools/memory_stats'
> -PhusionPassenger.locate_directories
>  stats = PhusionPassenger::AdminTools::MemoryStats.new
>  unless stats.platform_provides_private_dirty_rss_information?
>    puts 'Please run as root or platform unsupported'

Yes, this works, thanks!

> 
> 
> But the real problem is that Passenger does think it supports
> getting process private dirty RSS memory information only on Linux:
> 
> https://github.com/phusion/passenger/blob/219ad24159ae4033a342e6ad753
> cfee05d98bae0/src/ruby_supportlib/phusion_passenger/admin_tools/memor
> y_stats.rb#L121
> 
> In file
> src/ruby_supportlib/phusion_passenger/admin_tools/memory_stats.rb:
> 
> 120       def platform_provides_private_dirty_rss_information?
> 121         return os_name_simple == "linux"
> 122       end
> 
> This support probably would need to be written. So, unfortunately,
> passenger-recycler
> as written will exit with:
> 
> 	Please run as root or platform unsupported

Yes, I have now gotten to this stage at least, thank you very much! I
don´t mind having a look at it, it might be simplest thing to write, or
it´s hell, but I´ll have a look!

Thank you for pointing me in the right direction!

/K

> 
> But passenger-recycler does something very simple - if the amount of
> "private resident RSS
> memory" is higher than specified amount in the configuration file, it
> kills the process.
> 
> You might get a much better monitoring on FreeBSD by monitoring the
> output of
> 
> procstat -v <processid>
> 
> which will give you details about the memory usage of the process and
> see how it is growing
> over time. Maybe you can pinpoint the shared library that causes
> this, if you are lucky.
> 
> Marcin
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