docs/performance/memory/memory.md

   1 # Memory Tools
   2
   3 The Memory tool lets you take a snapshot of the current tab's memory
   4 [heap](https://en.wikipedia.org/wiki/Memory_management#HEAP).
   5 It then provides a number of views of the heap that can
   6 show you which objects account for memory usage and exactly where in
   7 your code you are allocating memory.
   8
   9 <iframe width="595" height="325" src="https://www.youtube.com/embed/DJLoq5E5ww0" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture"></iframe>
  10
  11 ------------------------------------------------------------------------
  12
  13 ## The basics
  14 -   Opening [the memory
  15     tool](basic_operations.md#opening-the-memory-tool)
  16 -   [Taking a heap
  17     snapshot](basic_operations.md#saving-and-loading-snapshots)
  18 -   [Comparing two
  19     snapshots](basic_operations.md#comparing-snapshots)
  20 -   [Deleting
  21     snapshots](basic_operations.md#clearing-a-snapshot)
  22 -   [Saving and loading
  23     snapshots](basic_operations.md#saving-and-loading-snapshots)
  24 -   [Recording call
  25     stacks](basic_operations.md#recording-call-stacks)
  26
  27 ------------------------------------------------------------------------
  28
  29 ## Analyzing snapshots
  30
  31 The Tree map view is new in Firefox 48, and the Dominators view is new
  32 in Firefox 46.
  33
  34 Once you've taken a snapshot, there are three main views the Memory
  35 tool provides:
  36
  37 -   [the Tree map view](tree_map_view.md) shows
  38     memory usage as a
  39     [treemap](https://en.wikipedia.org/wiki/Treemapping).
  40 -   [the Aggregate view](aggregate_view.md) shows
  41     memory usage as a table of allocated types.
  42 -   [the Dominators view](dominators_view.md)
  43     shows the "retained size" of objects: that is, the size of objects
  44     plus the size of other objects that they keep alive through
  45     references.
  46
  47 If you've opted to record allocation stacks for the snapshot, the
  48 Aggregate and Dominators views can show you exactly where in your code
  49 allocations are happening.
  50
  51 ------------------------------------------------------------------------
  52
  53 ## Concepts
  54
  55 -   What are [Dominators](dominators.md)?
  56
  57 ------------------------------------------------------------------------
  58
  59 ## Example pages
  60
  61 Examples used in the Memory tool documentation.
  62
  63 -   The [Monster example](monster_example.md)
  64 -   The [DOM allocation example](DOM_allocation_example.md)