discourse/lib/memory_diagnostics.rb

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module MemoryDiagnostics
def self.snapshot_exists?
File.exists?(snapshot_filename)
end
def self.compare(from=nil, to=nil)
from ||= snapshot_filename
if !to
filename = snapshot_filename + ".new"
snapshot_current_process(filename)
to = filename
end
from = Marshal::load(IO.binread(from));
to = Marshal::load(IO.binread(to));
diff = from - to
require 'objspace'
diff = diff.map do |id|
ObjectSpace._id2ref(id) rescue nil
end.compact!
report = "#{diff.length} objects have leaked\n"
report << "Summary:\n"
summary = {}
diff.each do |obj|
begin
summary[obj.class] ||= 0
summary[obj.class] += 1
rescue
# don't care
end
end
report << summary.sort{|a,b| b[1] <=> a[1]}[0..50].map{|k,v|
"#{k}: #{v}"
}.join("\n")
report << "\n\nSample Items:\n"
diff[0..5000].each do |v|
report << "#{v.class}: #{String === v ? v[0..300] : (40 + ObjectSpace.memsize_of(v)).to_s + " bytes"}\n" rescue nil
end
report
end
def self.snapshot_path
"#{Rails.root}/tmp/mem_snapshots"
end
def self.snapshot_filename
"#{snapshot_path}/#{Process.pid}.snapshot"
end
def self.snapshot_current_process(filename=nil)
filename ||= snapshot_filename
pid=fork do
snapshot(filename)
end
Process.wait(pid)
end
def self.snapshot(filename)
require 'objspace'
FileUtils.mkdir_p snapshot_path
object_ids = []
full_gc
ObjectSpace.each_object do |o|
begin
object_ids << o.object_id
rescue
# skip
end
end
IO.binwrite(filename, Marshal::dump(object_ids))
end
def self.memory_report(opts={})
begin
# ruby 2.1
GC.start(full_mark: true)
rescue
GC.start
end
classes = {}
large_objects = []
if opts[:class_report]
require 'objspace'
ObjectSpace.each_object do |o|
begin
classes[o.class] ||= 0
classes[o.class] += 1
if (size = ObjectSpace.memsize_of(o)) > 200
large_objects << [size, o]
end
rescue
# all sorts of stuff can happen here BasicObject etc.
classes[:unknown] ||= 0
classes[:unknown] += 1
end
end
classes = classes.sort{|a,b| b[1] <=> a[1]}[0..40].map{|klass, count| "#{klass}: #{count}"}
classes << "\nLarge Objects (#{large_objects.length} larger than 200 bytes total size #{large_objects.map{|x,_| x}.sum}):\n"
classes += large_objects.sort{|a,b| b[0] <=> a[0]}[0..800].map do |size,object|
rval = "#{object.class}: size #{size}"
rval << " " << object.to_s[0..500].gsub("\n", "") if (String === object) || (Regexp === object)
rval << "\n"
rval
end
end
stats = GC.stat.map{|k,v| "#{k}: #{v}"}
counts = ObjectSpace.count_objects.sort{|a,b| b[1] <=> a[1] }.map{|k,v| "#{k}: #{v}"}
<<TEXT
#{`hostname`.strip} pid:#{Process.pid} #{`cat /proc/#{Process.pid}/cmdline`.strip.gsub(/[^a-z1-9\/]/i, ' ')}
GC STATS:
#{stats.join("\n")}
Objects:
#{counts.join("\n")}
Process Info:
#{`cat /proc/#{Process.pid}/status`}
Classes:
#{classes.length > 0 ? classes.join("\n") : "Class report omitted use ?full=1 to include it"}
TEXT
end
def self.full_gc
# gc start may not collect everything
GC.start while new_count = decreased_count(new_count)
end
def self.decreased_count(old)
count = count_objects
if !old || count < old
count
else
nil
end
end
def self.count_objects
i = 0
ObjectSpace.each_object do |obj|
i += 1
end
end
end