fix(profiling): reduce lock profiler log spam [backport 2.16] (#11388)

Backport 079e478 from #11377 to 2.16.

The lock profiler would log a warning if it couldn't determine a
name for a lock, and it would try determining a name multiple times for
the same lock.  This lead to excessive log spam. Downgrade this to a
debug log and only try to determine the name once.

## Checklist
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- The PR description articulates the motivation for the change
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strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
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[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [x] Reviewer has checked that all the criteria below are met 
- Title is accurate
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PROF-10898

Co-authored-by: Nick Ripley <[email protected]>
Co-authored-by: Taegyun Kim <[email protected]>

ddtrace/profiling/collector/_lock.py

@@ -269,7 +269,7 @@ def _find_self_name(self, var_dict: typing.Dict):
 
     # Get lock acquire/release call location and variable name the lock is assigned to
     def _maybe_update_self_name(self):
-        if self._self_name:
+        if self._self_name is not None:
             return
         try:
             # We expect the call stack to be like this:
@@ -298,7 +298,7 @@ def _maybe_update_self_name(self):
 
             if not self._self_name:
                 self._self_name = ""
-                LOG.warning(
+                LOG.debug(
                     "Failed to get lock variable name, we only support local/global variables and their attributes."
                 )
 

releasenotes/notes/profiling-reduce-lock-profiler-log-spam-5931d957ff1becd4.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    profiling: The lock profiler would log a warning if it couldn't determine a
+      name for a lock, and it would try determining a name multiple times for
+      the same lock.  This lead to excessive log spam. Downgrade this to a
+      debug log and only try to determine the name once.