fix: add timeout handling for subprocess wait [backport 3.3] (#12904)

Backport b518cfd from #12806 to 3.3.

After subprocess is opened, wait and kill if Timeout is exceeded to
ensure zombie processes are killed.

## Checklist
- [x] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
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
- Backport labels are set (if
[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
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
- 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)

https://datadoghq.atlassian.net/browse/APMLP-313

Co-authored-by: Quinna Halim <[email protected]>

Author: github-actions[bot]

lib-injection/sources/sitecustomize.py

@@ -148,7 +148,7 @@ def gen_telemetry_payload(telemetry_events, ddtrace_version):
     }
 
 
-def send_telemetry(event):
+def _send_telemetry(event):
     event_json = json.dumps(event)
     _log("maybe sending telemetry to %s" % FORWARDER_EXECUTABLE, level="debug")
     if not FORWARDER_EXECUTABLE or not TELEMETRY_ENABLED:
@@ -161,15 +161,38 @@ def send_telemetry(event):
         stderr=subprocess.PIPE,
         universal_newlines=True,
     )
-    if p.stdin:
-        p.stdin.write(event_json)
-        p.stdin.close()
-        _log("wrote telemetry to %s" % FORWARDER_EXECUTABLE, level="debug")
-    else:
-        _log(
-            "failed to write telemetry to %s, could not write to telemetry writer stdin" % FORWARDER_EXECUTABLE,
-            level="error",
-        )
+    # Mimic Popen.__exit__ which was added in Python 3.3
+    try:
+        if p.stdin:
+            p.stdin.write(event_json)
+            _log("wrote telemetry to %s" % FORWARDER_EXECUTABLE, level="debug")
+        else:
+            _log(
+                "failed to write telemetry to %s, could not write to telemetry writer stdin" % FORWARDER_EXECUTABLE,
+                level="error",
+            )
+    finally:
+        if p.stdin:
+            p.stdin.close()
+        if p.stderr:
+            p.stderr.close()
+        if p.stdout:
+            p.stdout.close()
+
+        # backwards compatible `p.wait(1)`
+        start = time.time()
+        while p.poll() is None:
+            if time.time() - start > 1:
+                p.kill()
+                break
+            time.sleep(0.05)
+
+
+def send_telemetry(event):
+    try:
+        _send_telemetry(event)
+    except Exception as e:
+        _log("Failed to send telemetry: %s" % e, level="error")
 
 
 def _get_clib():

releasenotes/notes/fix-lib-injection-zombie-dc16ca6c8bf50edb.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    lib-injection: Avoid zombie process from telemetry sender on startup.