Class: Stalin::Watcher::LinuxProcStatm

Inherits:
Object
  • Object
show all
Defined in:
lib/stalin/watcher/linux_proc_statm.rb

Overview

Watcher that uses procfs (specifically /proc/<pid>/statm) to determine memory usage.

Instance Method Summary collapse

Constructor Details

#initialize(pid) ⇒ LinuxProcStatm

Returns a new instance of LinuxProcStatm.

Parameters:

  • pid (Integer) —

    target process ID

Raises:



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# File 'lib/stalin/watcher/linux_proc_statm.rb', line 6

def initialize(pid)
  @statm = "/proc/%d/statm" % [pid]
  raise Stalin::Unsupported, "Unreadable or nonexistent file: #{@statm}" unless File.readable?(@statm)

  page_size = `getconf PAGESIZE`
  @page_size = Integer(page_size) rescue nil
  raise Stalin::Unsupported, "Cannot determine page size: #{page_size}" unless $?.success? && @page_size.kind_of?(Integer)
end

Instance Method Details

#watch ⇒ Integer?

Report on memory usage.

Returns:

  • (Integer, nil) —

    target process’ memory usage in bytes, nil if process not found



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# File 'lib/stalin/watcher/linux_proc_statm.rb', line 18

def watch
  vsz, rss, shared = File.read(@statm).split(' ')
  vsz              = Integer(vsz) * @page_size
  rss              = Integer(rss) * @page_size
  shared           = Integer(shared) * @page_size

  rss
rescue SystemCallError
  # assume any failure means that process has gone away
  nil
end