gh-114312: Collect stats for unlikely events

[mdboom]

This has been benchmarked here (1.00x faster) and the stats collected from the pyperformance suite are:

Event	Count
set_class	0
set_bases	40
set_eval_frame_func	0
builtin_dict	0
func_modification	220

• Issue: Add stats for "unlikely events" that will impact optimization. #114312

[mdboom]

Note that modifying func.__closure__ (mentioned in the original bug) isn't possible, so that's another one we don't need to worry about.

[mdboom]

Just for interest: The set_bases mutation is all from the mypy2 benchmark, and func_modifications comes from async_generators, dask, docutils and mypy2.

[markshannon]

This is great. Thanks.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot aarch64 Debian Clang LTO + PGO 3.x has failed when building commit ea3cd04.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/1084/builds/3189) and take a look at the build logs.
4. Check if the failure is related to this commit (ea3cd04) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/1084/builds/3189

Failed tests:

• test_optimizer

Failed subtests:

• test_func_modification - test.test_optimizer.TestRareEventCounters.test_func_modification
• test_builtin_dict - test.test_optimizer.TestRareEventCounters.test_builtin_dict

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/var/lib/buildbot/workers/arm64-clang/3.x.gps-arm64-debian.clang.lto-pgo/build/Lib/test/test_optimizer.py", line 69, in test_func_modification
    self.assertEqual(
    ~~~~~~~~~~~~~~~~^
        orig_counter + 1,
        ^^^^^^^^^^^^^^^^^
        _testinternalcapi.get_rare_event_counters()["func_modification"]
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
AssertionError: 187647121162244 != 281470681743364


Traceback (most recent call last):
  File "/var/lib/buildbot/workers/arm64-clang/3.x.gps-arm64-debian.clang.lto-pgo/build/Lib/test/test_optimizer.py", line 52, in test_builtin_dict
    self.assertEqual(
    ~~~~~~~~~~~~~~~~^
        orig_counter + 1,
        ^^^^^^^^^^^^^^^^^
        _testinternalcapi.get_rare_event_counters()["builtin_dict"]
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
AssertionError: 281470681743361 != 187647121162241

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot aarch64 RHEL8 3.x has failed when building commit ea3cd04.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/529/builds/5782) and take a look at the build logs.
4. Check if the failure is related to this commit (ea3cd04) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/529/builds/5782

Failed tests:

• test_optimizer

Failed subtests:

• test_func_modification - test.test_optimizer.TestRareEventCounters.test_func_modification

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-aarch64/build/Lib/test/test_optimizer.py", line 69, in test_func_modification
    self.assertEqual(
    ~~~~~~~~~~~~~~~~^
        orig_counter + 1,
        ^^^^^^^^^^^^^^^^^
        _testinternalcapi.get_rare_event_counters()["func_modification"]
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
AssertionError: 8320542925956055046 != 281470681743366


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-aarch64/build/Lib/test/test_optimizer.py", line 69, in test_func_modification
    self.assertEqual(
    ~~~~~~~~~~~~~~~~^
        orig_counter + 1,
        ^^^^^^^^^^^^^^^^^
        _testinternalcapi.get_rare_event_counters()["func_modification"]
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
AssertionError: 9897122950987907078 != 281470681743366

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot aarch64 RHEL8 LTO 3.x has failed when building commit ea3cd04.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/338/builds/5946) and take a look at the build logs.
4. Check if the failure is related to this commit (ea3cd04) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/338/builds/5946

Failed tests:

• test_optimizer

Failed subtests:

• test_func_modification - test.test_optimizer.TestRareEventCounters.test_func_modification

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-aarch64.lto/build/Lib/test/test_optimizer.py", line 69, in test_func_modification
    self.assertEqual(
    ~~~~~~~~~~~~~~~~^
        orig_counter + 1,
        ^^^^^^^^^^^^^^^^^
        _testinternalcapi.get_rare_event_counters()["func_modification"]
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
AssertionError: 281470681743366 != 6

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot aarch64 Fedora Stable LTO 3.x has failed when building commit ea3cd04.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/336/builds/4578) and take a look at the build logs.
4. Check if the failure is related to this commit (ea3cd04) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/336/builds/4578

Failed tests:

• test_optimizer

Failed subtests:

• test_func_modification - test.test_optimizer.TestRareEventCounters.test_func_modification

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-aarch64.lto/build/Lib/test/test_optimizer.py", line 69, in test_func_modification
    self.assertEqual(
    ~~~~~~~~~~~~~~~~^
        orig_counter + 1,
        ^^^^^^^^^^^^^^^^^
        _testinternalcapi.get_rare_event_counters()["func_modification"]
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
AssertionError: 281470681743366 != 6