gh-102567: Add -X importtime=2 for logging an importtime message for already-loaded modules

[noahbkim]

As mentioned in the issue:

While -X importtime is incredibly useful for analyzing module import times, by design, it doesn't log anything if an imported module has already been loaded. -X importtime=2 would provide additional output for every module that's already been loaded:

The updated example:

>>> import uuid
import time: cached    | cached     | builtins
import time: cached    | cached     | linecache
import time: cached    | cached     |   _io
import time: cached    | cached     |   os
import time: cached    | cached     |   sys
import time: cached    | cached     |   enum
import time:       594 |        594 |   _uuid
import time:      2428 |       3022 | uuid

Discussion: https://discuss.python.org/t/x-importtrace-to-supplement-x-importtime-for-loaded-modules/23882/5
Prior email chain: https://mail.python.org/archives/list/python-ideas@python.org/thread/GEISYQ5BXWGKT33RWF77EOSOMMMFUBUS/

• Issue: Add -X importtime=2 for additional logging when an imported module is already loaded #102567

[Eclips4]

Hello!
This PR needs to add:

1. A NEWS entry
2. A whatsnew entry
3. A new paragraph in the Doc/cmdline for the -X option.
4. New test case in the Lib/test/test_cmd_line

[noahbkim]

Hello! This PR needs to add:

1. A NEWS entry
2. A whatsnew entry
3. A new paragraph in the Doc/cmdline for the -X option.
4. New test case in the Lib/test/test_cmd_line

Thanks for the quick feedback. I've committed a first pass of 1-3. As for tests: there appear to be no importtime tests (likely due to the fact that any simple implementation would be super noisy as other parts of the interpreter change). Would it be sufficient to do some rudimentary check i.e. import foo then ensure a corresponding foo row appears in the output?

Thanks again!

[Eclips4]

Hello! This PR needs to add:

1. A NEWS entry
2. A whatsnew entry
3. A new paragraph in the Doc/cmdline for the -X option.
4. New test case in the Lib/test/test_cmd_line

Thanks for the quick feedback. I've committed a first pass of 1-3. As for tests: there appear to be no importtime tests (likely due to the fact that any simple implementation would be super noisy as other parts of the interpreter change). Would it be sufficient to do some rudimentary check i.e. import foo then ensure a corresponding foo row appears in the output?

Thanks again!

Yes, it would be sufficient :)

[Eclips4]

Also, there's a merge conflict. Can you resolve it? (I can do it myself, but it seems like you have turned off this option)

[noahbkim]

Also, there's a merge conflict. Can you resolve it? (I can do it myself, but it seems like you have turned off this option)

Done, just added tests as well

[noahbkim]

@Eclips4 who should I ping to get final review? Is it alright if I @ the blamed reviewers?

[Eclips4]

@Eclips4 who should I ping to get final review? Is it alright if I @ the blamed reviewers?

I guess @vstinner is the right person to review this 😄
However, you should move your changes from whatsnew/3.13.rst to whatsnew/3.14.rst since 3.13 branch is in feature-freeze mode, and this feature will appear only in the 3.14 version.

[Eclips4]

However, you should move your changes from whatsnew/3.13.rst to whatsnew/3.14.rst since 3.13 branch is in feature-freeze mode, and this feature will appear only in the 3.14 version.

The same applies for the versionchanged directives.