(Graphical version at the end)

Multi-core Python

A per-interpreter GIL

• Per-interpreter isolation for extension modules

• A CI check to prevent new globals in CPython code

  • Tooling to identify global variables in CPython code

• Interpreter isolation (_PyRuntimeState -> PyInterpreterState)

  • Consolidate global state to _PyRuntimeState

    • Tooling to identify global variables in CPython code (also above)

  • PEP 683 - immortal objects

  • mimalloc

• Restrictions on interpreter capability (e.g. no threading)

  • Per-interpreter config & func to specify restrictions

• PEP 684: A Per-interpreter GIL

Expose multiple interpreters to Python code

• Implement PEP 554

  • PEP 554 - Multiple Interpreters in the Stdlib

Reduced Reference Count Overhead

Reduced reference counting overhead

• Optimize flow of references in C, transferring ownership when needed

  • Identify flow of references in C

• Static reduction in refcount operations

  • Bytecode compiler enhancements Irit

  • Deferred reference counts

• Deferred reference counts (also above)

Improve cycle GC

• (Task needs breaking up)

Compact Objects

Compact objects

• Merge managed dict and values pointer into one word

• One word GC header

  • Saturating refcounts

Specialization

Finish specialization

• Specialize SEND

  • Specialize FOR_ITER for generator

    • Specialize FOR_ITER for sequences Dennis

    • Shim frames on entry to PyEval_EvalDefault

      • Identify main sources of calls to PyEval_EvalFrame

  • Move PEP 380 logic into compiler Brandt

Trace optimized interpreter

Projected (short) trace opimized interpreter

• Optimize traces: Guard stengthening and elimination

  • Trace interpreter (also below)

• Optimize traces: Allocation elimination

  • Trace interpreter

    • Breakup instruction definitions into 'mini-ops' (see below)

    • Trace projection: Create traces from hotspots

      • Detect hotspots in code

        • Only unconditional jumps should go backwards

      • Implement optimizer API

      • Generate version of the interpreter better suited to emscripten and web assembly

      • Breakup instruction definitions into 'mini-ops'

        • Move opcode definitions to their own file and generate PyEval_EvalDefault (also below)

          • Move PEP 380 logic into compiler Brandt (also above)

        • Encapasulate GIL code and move it out of ceval.c #93177

• Generate version of the interpreter better suited to emscripten and web assembly (goal without dependents?)

  • Move opcode definitions to their own file and generate PyEval_EvalDefault (also above)