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20 lines
1,002 B
Markdown
20 lines
1,002 B
Markdown
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# AOT Snapshot Size Profiling
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The VM supports profiling the size of AOT snapshots by leveraging the object-graph based file format introduced by V8.
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## Recording a profile
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To generate a snapshot profile, simply pass the `--write-v8-snapshot-profile-to=<filename>` flag to `gen_snapshot`.
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The profile will be written in JSON format to the requested file.
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Make sure to use the ".heapsnaphsot" extension for the file to open it in Chrome DevTools.
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## Examining a profile in Chrome
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Open Chrome DevTools, navigate to the "Memory" tab, right-click on the "Profiles" panel, click Load..." and select the snapshot profile file.
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See https://developers.google.com/web/tools/chrome-devtools/memory-problems/heap-snapshots for details on how to use the tool.
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## Examining a profile programmatically
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A Dart library to parse the snapshot profile format is provided in `pkg/vm/lib/v8_snaphsot_profile.dart`.
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The `dart2js_info` package has some useful code for calculating retainers and other graph statistics.
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