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Zurihac 2019 Profiler Ideas

Last edited by Matthew Pickering
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There are a few different projects of different skills levels which I (@mpickering) would be willing to help with at Zurihac. The first is continuing the reimplementation of hp2pretty to work with eventlogs and HTML rendering. The second are improvements on the profiling code of GHC itself.

hp2pretty - Visualising Heap Profiles

Example

This repo is a reimplementation of hp2pretty, there is a new frontend which reads eventlogs and a new backend which renders the chart using a vega-lite) specification. The resulting chart is interactive.

  1. (Beginner) Improve the rendering of the heap profile.

    • Display which Constructor we currently mouse over.
    • Display heap usage of the constructor/total on that position.
    • Maybe we can change the colour of the event log line when emphasising it.
    • Allow selecting a specific part of the profiled to view (example)
    • Make it easy to switch between a "zero", "normalize" and "center" stack chart. This is easy to achieve statically but not dynamically using vega-lite. (vega-lite#3338)
    • Add a title and other meta information.

  2. (Intermediate) Continue refactoring the internals of hp2pretty.

    • Honour the --sort flag
    • Honour the --uniform flag
    • Honour the --reverse flag

  3. (Intermediate) Get hp2pretty ready for a release.

    • Vendor necessary javascript libraries so there are no runtime dependencies (For example js-flot
    • Embed generated JSON into html document.
    • Think of another name for the library

Improvements to GHC profiling (Intermediate/Advanced - knowledge of C)

  • Add a cost-centre profiling mode which inserts cost-centres AFTER optimisations have run. (This is mostly already implemented but needs to be tested)(#16765)
  • Dynamically adjust sampling interval in proportion to time taken to GC (#1420)
  • Add eventlog events for biographical and retainer profilers (#16766 (closed))
  • Add profiling support to ghc-heap(#15375)
  • LDV Profiling: Make heapCensus agree with LdcCensusForDead (#16807)
  • (Advanced) Give more detailed information about PINNED data in a heap profile (#7275)