Improve performance of sys.settracing based tools.

[markshannon]

BPO	45923
Nosy	@nedbat, @markshannon, @pablogsal, @brandtbucher
PRs	bpo-45923: Handle call events in bytecode #30364 bpo-45923: Add RESUME_QUICK #31244 bpo-45923: Decouple suspension of tracing from tracing flag. #31908

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/markshannon'
closed_at = None
created_at = <Date 2021-11-29.11:37:57.908>
labels = ['interpreter-core', '3.11', 'performance']
title = 'Improve performance of sys.settracing based tools.'
updated_at = <Date 2022-03-15.17:06:49.934>
user = 'https://github.com/markshannon'

bugs.python.org fields:

activity = <Date 2022-03-15.17:06:49.934>
actor = 'Mark.Shannon'
assignee = 'Mark.Shannon'
closed = False
closed_date = None
closer = None
components = ['Interpreter Core']
creation = <Date 2021-11-29.11:37:57.908>
creator = 'Mark.Shannon'
dependencies = []
files = []
hgrepos = []
issue_num = 45923
keywords = ['patch']
message_count = 4.0
messages = ['407263', '409842', '413017', '415267']
nosy_count = 4.0
nosy_names = ['nedbat', 'Mark.Shannon', 'pablogsal', 'brandtbucher']
pr_nums = ['30364', '31244', '31908']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'performance'
url = 'https://bugs.python.org/issue45923'
versions = ['Python 3.11']

[markshannon]

In our quest for performance, the performance of sys.settracing based tools has probably gotten worse.

1. How do we measure this?
2. How do fix this?

We will initially use coverage.py as proxy for all sys.settracing based tools when measuring performance.

The fix is probably to use quickening to insert a minimum set of instrumentation instructions required for tracing/profiling.
The existence of f_trace_opcode is a bit of a problem however, as we will have to instrument every instruction.

Ideally, sys.settracing based tools should be faster on 3.11 than 3.10, but at the least we should provide a simple alternative to sys.settracing that is faster.

[markshannon]

New changeset e028ae9 by Mark Shannon in branch 'main':
bpo-45923: Handle call events in bytecode (GH-30364)
e028ae9

[markshannon]

New changeset d7a5aca by Brandt Bucher in branch 'main':
bpo-45923: Add RESUME_QUICK (GH-31244)
d7a5aca

[markshannon]

New changeset 099f756 by Mark Shannon in branch 'main':
bpo-45923: Decouple suspension of tracing from tracing flag. (GH-31908)
099f756

[neonene]

Maybe this does not matter, but the pure python tracer of coverage.py has slowed down since 099f756:

pyperformance	before	099f756
coverage	684 ms	1.17 sec (171% )	Windows

[markshannon]

It doesn't matter as much as the performance of coverage.py C tracer, but it is still worth investigating.

[nedbat]

There have been some recent improvements in coverage.py for the Python tracing, which might compensate.

[markshannon]

Tools should have moved, or be moving, to using sys.monitoring now.