Visual representations of memory issues in Ruby

and RailsCamille Baldock, @camille_

Bloat

• Memory usage has grown with data set

• Loading too many objects at once

Memory leaks

• Objects that will never be released by the garbage collector

• Objects whose size grows the longer the process runs

Memory churn

• Allocating and deallocating a LOT of objects

• Oink

• Ruby object graphs

• A few best practices…

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Configuring Oink

• Rails.application.middleware.use( Oink::Middleware, :instruments => :memory )

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• Rails.application.middleware.use( Oink::Middleware, :instruments => :activerecord )

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• ReportsController#show

• Max heap size: 157524 KB

• Number of AR objects: 14565

Be proactive about

being lazy

Where are the leaks ?

• Look at the object graph in memory !

• ObjectSpace.find_references

• A new ObjectGraph standard library

Journey through the object graph

Counting objects…

Finding something horrible…

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• status?timestamp=110143244

• status?timestamp=110143245

• ….

Stop using global state !

• Global variables

• Class variables

• Per-process instance state

• …

My app is still slow…

Sources of memory churn

Mutation limits allocation

• Twitter: @camille_

• Github: camilleldn

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• Conrad Irwin, Object Graph exploration for Ruby memory leaks

• Oink gem, https://github.com/noahd1/oink

• Boston Ruby - Joe Ferris - Memory Issues in Rails