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

[Karli Sjöberg]

On Thu, 2018-02-22 at 10:11 +0100, Karli Sjöberg via freebsd-ports
wrote:
> On Thu, 2018-02-22 at 07:50 +0100, Karli Sjöberg via freebsd-ports
> wrote:
> > 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/219ad24159ae4033a342e6a
> > > d7
> > > 53
> > > cfee05d98bae0/src/ruby_supportlib/phusion_passenger/admin_tools/m
> > > em
> > > or
> > > 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.
> 
> How do I interpret the output of 'procstat -v <pid>' though? Can I
> sum
> up all of the RES or PRES numbers to get the total virtual memory
> that
> this process is consuming?

I hacked at it a bit and came up with an updated patch that includes
the changes you made, plus my own.

Since "private dirty RSS" isn´t available, I´ve used "maximum RSS" from
'procstat -r <pid>', which is far from perfect, but it´s better than
nothing. It now runs and does what you´d expect :)

I have attached it to this email.

/K

> 
/K


Marcin
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