fix(profiling): import protobuf only if needed [backport 1.20] (#7156)

Backport f4503a8 from #7124 to 1.20.

Importing protobuf when this is a shared dependency with the tracer
might cause issues. We make sure to import it only if necessary. This
means that we can avoid importing the protobuf Python module when
exporting exclusively via libdatadog.

## Checklist

- [x] Change(s) are motivated and described in the PR description.
- [x] Testing strategy is described if automated tests are not included
in the PR.
- [x] Risk is outlined (performance impact, potential for breakage,
maintainability, etc).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
are followed. If no release note is required, add label
`changelog/no-changelog`.
- [x] Documentation is included (in-code, generated user docs, [public
corp docs](https://github.com/DataDog/documentation/)).
- [x] Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist

- [x] Title is accurate.
- [x] No unnecessary changes are introduced.
- [x] Description motivates each change.
- [x] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
- [x] Testing strategy adequately addresses listed risk(s).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] Release note makes sense to a user of the library.
- [x] Reviewer has explicitly acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment.
- [x] Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)
- [x] If this PR touches code that signs or publishes builds or
packages, or handles credentials of any kind, I've requested a review
from `@DataDog/security-design-and-guidance`.
- [x] This PR doesn't touch any of that.

Co-authored-by: Gabriele N. Tornetta <[email protected]>

Author: github-actions[bot]

ddtrace/profiling/profiler.py

@@ -27,8 +27,6 @@
 from ddtrace.profiling.collector import stack
 from ddtrace.profiling.collector import stack_event
 from ddtrace.profiling.collector import threading
-from ddtrace.profiling.exporter import file
-from ddtrace.profiling.exporter import http
 from ddtrace.settings.profiling import config
 
 from . import _asyncio
@@ -138,6 +136,10 @@ def _build_default_exporters(self):
         # type: (...) -> List[exporter.Exporter]
         _OUTPUT_PPROF = config.output_pprof
         if _OUTPUT_PPROF:
+            # DEV: Import this only if needed to avoid importing protobuf
+            # unnecessarily
+            from ddtrace.profiling.exporter import file
+
             return [
                 file.PprofFileExporter(prefix=_OUTPUT_PPROF),
             ]
@@ -187,6 +189,10 @@ def _build_default_exporters(self):
             )
 
         if self._export_py_enabled:
+            # DEV: Import this only if needed to avoid importing protobuf
+            # unnecessarily
+            from ddtrace.profiling.exporter import http
+
             return [
                 http.PprofHTTPExporter(
                     service=self.service,

docs/spelling_wordlist.txt

@@ -264,3 +264,4 @@ Gitlab
 Enablement
 hotspot
 CMake
+libdatadog

releasenotes/notes/fix-profiler-protobuf-if-needed-9c64068ab27e7352.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    profiling: Load the protobuf module only if needed to avoid interfering with
+    the module state for applications that also make use of it. The protobuf
+    module is used in file and classic Python HTTP export. It is not needed for
+    the libdatadog-based exporter.