Hi all, I've reposted this to the python.org discussion board with a followup on `-X importtime=2`. I think it'll be more accessible if we move the conversation there.

Here's a link: https://discuss.python.org/t/x-importtrace-to-supplement-x-importtime-for-loaded-modules/23882/3

On Tue, Feb 14, 2023 at 9:45 PM Noah Kim <noahbkim@gmail.com> wrote:
I really like this approach!

> On Feb 14, 2023, at 9:04 PM, Inada Naoki <songofacandy@gmail.com> wrote:
>
> `-X importtime=2`
>
> This is expert-only tool. So no need for verbose name.
>
>> On Sat, Feb 11, 2023 at 10:01 PM Noah Kim <noahbkim@gmail.com> wrote:
>>
>> All,
>>
>> I'm writing to propose an adjacent interpreter flag to `-X importtime`: `-X importcache` (open to alternative naming).
>>
>> 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 importcache` would provide additional output for every module that's already been loaded:
>>
>> ```
>>>>> import uuid
>> import time: cached    | cached     |   _io
>> import time: cached    | cached     |   _io
>> import time: cached    | cached     |   os
>> import time: cached    | cached     |   sys
>> import time: cached    | cached     |   enum
>> import time: cached    | cached     |     _io
>> import time: cached    | cached     |     _io
>> import time: cached    | cached     |     collections
>> import time: cached    | cached     |     os
>> import time: cached    | cached     |     re
>> import time: cached    | cached     |     sys
>> import time: cached    | cached     |     functools
>> import time: cached    | cached     |     itertools
>> import time:       151 |        151 |     _wmi
>> import time:     18290 |      18440 |   platform
>> import time:       372 |        372 |   _uuid
>> import time:     10955 |      29766 | uuid
>> ```
>>
>> In codebases with convoluted/poorly managed import graphs (and consequently, workloads that suffer from long import times), the ability to record all paths to an expensive dependency--not just the first-imported--can help expedite refactoring (and help scale identification of this type of issue). More generally, this flag would provide a more efficient path to tracking runtime dependencies.
>>
>> As a proof of concept, I was able to hack this functionality into `-X importtime` by adding a couple lines to `import_ensure_initialized` in `Python/import.c` (hence the output above). A separate flag is probably desirable to preserve backwards compatibility.
>>
>> Looking forward to your feedback,
>> Noah
>>
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>
>
>
> --
> Inada Naoki  <songofacandy@gmail.com>