Analysing the size of code-related entities

This page provides an analysis for the size of the image, with a focus on the size of code entities, like methods and classes.

For performance reasons the vaues of these metrics are caches in GtMemoryMetrics Object << #GtMemoryMetrics slots: { #cache }; package: 'GToolkit-Releaser' . They can be reset using the snippet below.

GtMemoryMetrics reset
  

Current image size is 673.25 MiB.

Total analysed size: 226.25 MiB

Methods: 62.20 MiB for 428219 methods.

The size of methods includes all bytecodes, additional state and literals. Literals include strings and literal arrays, but excludes symbols.

String literals size: 7.64 MiB

Classes: 92.53 MiB for 31335 classess.

Instance Side: 37.38 MiB

Without method dictionaries: 13.22 MiB

By componets: 36.99 MiB

Method dictionaries: 24.16 MiB

Basic Size in Memory: 3.18 MiB

Other: 9.65 MiB

Subclasses: 284.42 KiB

Protocols: 6.12 MiB

Layout: 734.10 KiB

Shared pools: 2.53 MiB

Class side: 55.14 MiB (metaclasses)

Without method dictionaries: 32.03 MiB

By componets: 28.37 MiB

Method dictionaries: 23.12 MiB

Basic Size in Memory: 1.91 MiB

Other: 3.34 MiB

Protocols: 2.62 MiB

Layout: 734.41 KiB

By data:

Basic Size in Memory: 5.09 MiB

Method dictionaries: 47.28 MiB

Subclasses: 284.42 KiB

Protocols: 8.75 MiB

Shared pools: 2.53 MiB

Layout: 1.43 MiB

The size of classes includes the size of the class object and various method dictionaries, but excludes the actual methods in those dictionaries

Symbols: 6.51 MiB for 211811 symbols

Pragmas Cache: 5.04 MiB

GT Completion Cache: 56.08 MiB

Packages: 1.83 MiB

Navigation Environment: 2.05 MiB

When using traits, metaclasses use two extra arrays. This can introduce a memory overhead when traits have many users.

Traits overhead: 12.65 MiB

This measures the size of several types of instances, to double check that the previous calculations did not miss something.

MethodDictionary Dictionary << #MethodDictionary layout: VariableLayout; slots: {}; tag: 'Methods'; package: 'Kernel-CodeModel' sanity check:

77736 instances

74.04 MiB using HashedCollection>>#gtSpecificSizeInMemory gtSpecificSizeInMemory ^ self sizeInMemory + array sizeInMemory

31.70 MiB using #selector instancesSizeInMemory "Answers the number of bytes consumed by all its instances including their object header. Note: we do not use #allInstances as allInstancesDo: has a fallback for low memory" | bytes | bytes := 0. self allInstancesDo: [:each | bytes := bytes + each sizeInMemory ]. ^ bytes

CompiledMethod CompiledCode << #CompiledMethod layout: CompiledMethodLayout; slots: {}; tag: 'Methods'; package: 'Kernel-CodeModel' :

428380 instances

62.23 MiB using CompiledMethod>>#gtSpecificSizeInMemory gtSpecificSizeInMemory ^ super gtSpecificSizeInMemory + (self penultimateLiteral isMethodProperties ifTrue: [ self penultimateLiteral sizeInMemory ] ifFalse: [ 0 ])

36.30 MiB using #selector instancesSizeInMemory "Answers the number of bytes consumed by all its instances including their object header. Note: we do not use #allInstances as allInstancesDo: has a fallback for low memory" | bytes | bytes := 0. self allInstancesDo: [:each | bytes := bytes + each sizeInMemory ]. ^ bytes

CompiledBlock CompiledCode << #CompiledBlock layout: CompiledMethodLayout; slots: {}; tag: 'Methods'; package: 'Kernel-CodeModel' instances

123857 instances

7.22 MiB using #selector instancesSizeInMemory "Answers the number of bytes consumed by all its instances including their object header. Note: we do not use #allInstances as allInstancesDo: has a fallback for low memory" | bytes | bytes := 0. self allInstancesDo: [:each | bytes := bytes + each sizeInMemory ]. ^ bytes