fix: pytest deadlock when using gevent [backport 2.8] (#9166)

Backport
9e862f9
from #9141 to 2.8.

Fixes #8281

This fix resolves an issue when using ``pytest`` + ``gevent`` where the
telemetry writer was eager initialized by ``pytest`` entrypoints loading
of our plugin causing a potential dead lock.

The specific case that we targeted solving with this PR:

```python
import ddtrace

import gevent.monkey

gevent.monkey.patch_all()

def test_thing():
    pass
```

```shell
$ pytest test.py
$ pytest -p ddtrace -p ddtrace.pytest_bdd -p ddtrace.pytest_benchmark test.py
$ pytest -p no:ddtrace -p no:ddtrace.pytest_bdd -p no:ddtrace.pytest_benchmark test.py
```

Previously would dead-lock, but now will execute without problem.

We no longer get telemetry enabled and sending data just from `import
ddtrace`.

Moving telemetry writer starting to `ddtrace.bootstrap.preload` will
mean that any unhandled exceptions that occur before the telemetry
writer can be started will not get reported.

- [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] Risks are described (performance impact, potential for breakage,
maintainability)
- [x] Change is maintainable (easy to change, telemetry, documentation)
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
are followed or label `changelog/no-changelog` is set
- [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))
- [x] If this PR changes the public interface, I've notified
`@DataDog/apm-tees`.

- [x] Title is accurate
- [x] All changes are related to the pull request's stated goal
- [x] Description motivates each change
- [x] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- [x] Testing strategy adequately addresses listed risks
- [x] Change is maintainable (easy to change, telemetry, documentation)
- [x] Release note makes sense to a user of the library
- [x] Author has 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)

.riot/requirements/1b90fc9.txt

@@ -0,0 +1,29 @@
+#
+# This file is autogenerated by pip-compile with Python 3.10
+# by the following command:
+#
+#    pip-compile --no-annotate --resolver=backtracking .riot/requirements/1b90fc9.in
+#
+attrs==23.2.0
+coverage[toml]==7.5.0
+exceptiongroup==1.2.1
+gevent==24.2.1
+greenlet==3.0.3
+hypothesis==6.45.0
+iniconfig==2.0.0
+mock==5.1.0
+msgpack==1.0.8
+opentracing==2.4.0
+packaging==24.0
+pluggy==1.5.0
+pytest==8.2.0
+pytest-cov==5.0.0
+pytest-mock==3.14.0
+pytest-randomly==3.15.0
+sortedcontainers==2.4.0
+tomli==2.0.1
+zope-event==5.0
+zope-interface==6.3
+
+# The following packages are considered to be unsafe in a requirements file:
+# setuptools

.riot/requirements/27d0ff3.txt

@@ -0,0 +1,31 @@
+#
+# This file is autogenerated by pip-compile with Python 3.8
+# by the following command:
+#
+#    pip-compile --no-annotate .riot/requirements/27d0ff3.in
+#
+attrs==23.2.0
+coverage[toml]==7.5.0
+exceptiongroup==1.2.1
+gevent==24.2.1
+greenlet==3.0.3
+hypothesis==6.45.0
+importlib-metadata==7.1.0
+iniconfig==2.0.0
+mock==5.1.0
+msgpack==1.0.8
+opentracing==2.4.0
+packaging==24.0
+pluggy==1.5.0
+pytest==8.2.0
+pytest-cov==5.0.0
+pytest-mock==3.14.0
+pytest-randomly==3.15.0
+sortedcontainers==2.4.0
+tomli==2.0.1
+zipp==3.18.1
+zope-event==5.0
+zope-interface==6.3
+
+# The following packages are considered to be unsafe in a requirements file:
+# setuptools

.riot/requirements/11fe1f6.txt → .riot/requirements/2d19e52.txt

@@ -2,24 +2,31 @@
 # This file is autogenerated by pip-compile with Python 3.7
 # by the following command:
 #
-#    pip-compile --config=pyproject.toml --no-annotate --resolver=backtracking .riot/requirements/11fe1f6.in
+#    pip-compile --config=pyproject.toml --no-annotate --resolver=backtracking .riot/requirements/2d19e52.in
 #
-attrs==23.1.0
+attrs==23.2.0
 coverage[toml]==7.2.7
-exceptiongroup==1.2.0
+exceptiongroup==1.2.1
+gevent==22.10.2
+greenlet==3.0.3
 hypothesis==6.45.0
 importlib-metadata==6.7.0
 iniconfig==2.0.0
 mock==5.1.0
 msgpack==1.0.5
 opentracing==2.4.0
-packaging==23.2
+packaging==24.0
 pluggy==1.2.0
-pytest==7.4.3
+pytest==7.4.4
 pytest-cov==4.1.0
 pytest-mock==3.11.1
 pytest-randomly==3.12.0
 sortedcontainers==2.4.0
 tomli==2.0.1
 typing-extensions==4.7.1
 zipp==3.15.0
+zope-event==5.0
+zope-interface==6.3
+
+# The following packages are considered to be unsafe in a requirements file:
+# setuptools

.riot/requirements/61891b4.txt

@@ -0,0 +1,31 @@
+#
+# This file is autogenerated by pip-compile with Python 3.9
+# by the following command:
+#
+#    pip-compile --no-annotate .riot/requirements/61891b4.in
+#
+attrs==23.2.0
+coverage[toml]==7.5.0
+exceptiongroup==1.2.1
+gevent==24.2.1
+greenlet==3.0.3
+hypothesis==6.45.0
+importlib-metadata==7.1.0
+iniconfig==2.0.0
+mock==5.1.0
+msgpack==1.0.8
+opentracing==2.4.0
+packaging==24.0
+pluggy==1.5.0
+pytest==8.2.0
+pytest-cov==5.0.0
+pytest-mock==3.14.0
+pytest-randomly==3.15.0
+sortedcontainers==2.4.0
+tomli==2.0.1
+zipp==3.18.1
+zope-event==5.0
+zope-interface==6.3
+
+# The following packages are considered to be unsafe in a requirements file:
+# setuptools

.riot/requirements/d171c08.txt

@@ -0,0 +1,27 @@
+#
+# This file is autogenerated by pip-compile with Python 3.11
+# by the following command:
+#
+#    pip-compile --no-annotate .riot/requirements/d171c08.in
+#
+attrs==23.2.0
+coverage[toml]==7.5.0
+gevent==24.2.1
+greenlet==3.0.3
+hypothesis==6.45.0
+iniconfig==2.0.0
+mock==5.1.0
+msgpack==1.0.8
+opentracing==2.4.0
+packaging==24.0
+pluggy==1.5.0
+pytest==8.2.0
+pytest-cov==5.0.0
+pytest-mock==3.14.0
+pytest-randomly==3.15.0
+sortedcontainers==2.4.0
+zope-event==5.0
+zope-interface==6.3
+
+# The following packages are considered to be unsafe in a requirements file:
+# setuptools

.riot/requirements/de578a7.txt

@@ -0,0 +1,27 @@
+#
+# This file is autogenerated by pip-compile with Python 3.12
+# by the following command:
+#
+#    pip-compile --no-annotate .riot/requirements/de578a7.in
+#
+attrs==23.2.0
+coverage[toml]==7.5.0
+gevent==24.2.1
+greenlet==3.0.3
+hypothesis==6.45.0
+iniconfig==2.0.0
+mock==5.1.0
+msgpack==1.0.8
+opentracing==2.4.0
+packaging==24.0
+pluggy==1.5.0
+pytest==8.2.0
+pytest-cov==5.0.0
+pytest-mock==3.14.0
+pytest-randomly==3.15.0
+sortedcontainers==2.4.0
+zope-event==5.0
+zope-interface==6.3
+
+# The following packages are considered to be unsafe in a requirements file:
+# setuptools

ddtrace/__init__.py

@@ -22,16 +22,6 @@
 
 from .settings import _config as config
 
-if config._telemetry_enabled:
-    from ddtrace.internal import telemetry
-
-    telemetry.install_excepthook()
-    # In order to support 3.12, we start the writer upon initialization.
-    # See https://github.com/python/cpython/pull/104826.
-    # Telemetry events will only be sent after the `app-started` is queued.
-    # This will occur when the agent writer starts.
-    telemetry.telemetry_writer.enable()
-
 from ._monkey import patch  # noqa: E402
 from ._monkey import patch_all  # noqa: E402
 from .internal.utils.deprecations import DDTraceDeprecationWarning  # noqa: E402

ddtrace/bootstrap/preload.py

@@ -42,6 +42,18 @@ def register_post_preload(func: t.Callable) -> None:
 log = get_logger(__name__)
 
 
+# Enable telemetry writer and excepthook as early as possible to ensure we capture any exceptions from initialization
+if config._telemetry_enabled:
+    from ddtrace.internal import telemetry
+
+    telemetry.install_excepthook()
+    # In order to support 3.12, we start the writer upon initialization.
+    # See https://github.com/python/cpython/pull/104826.
+    # Telemetry events will only be sent after the `app-started` is queued.
+    # This will occur when the agent writer starts.
+    telemetry.telemetry_writer.enable()
+
+
 if profiling_config.enabled:
     log.debug("profiler enabled via environment variable")
     try:

ddtrace/internal/runtime/runtime_metrics.py

@@ -7,14 +7,13 @@
 import attr
 
 import ddtrace
+from ddtrace import config
 from ddtrace.internal import atexit
 from ddtrace.internal import forksafe
 
 from .. import periodic
-from .. import telemetry
 from ..dogstatsd import get_dogstatsd_client
 from ..logger import get_logger
-from ..telemetry.constants import TELEMETRY_RUNTIMEMETRICS_ENABLED
 from .constants import DEFAULT_RUNTIME_METRICS
 from .metric_collectors import GCRuntimeMetricCollector
 from .metric_collectors import PSUtilRuntimeMetricCollector
@@ -24,6 +23,10 @@
 
 log = get_logger(__name__)
 
+if config._telemetry_enabled:
+    import ddtrace.internal.telemetry as telemetry
+    from ddtrace.internal.telemetry.constants import TELEMETRY_RUNTIMEMETRICS_ENABLED
+
 
 class RuntimeCollectorsIterable(object):
     def __init__(self, enabled=None):
@@ -108,7 +111,8 @@ def disable(cls):
             cls.enabled = False
 
         # Report status to telemetry
-        telemetry.telemetry_writer.add_configuration(TELEMETRY_RUNTIMEMETRICS_ENABLED, False, origin="unknown")
+        if config._telemetry_enabled:
+            telemetry.telemetry_writer.add_configuration(TELEMETRY_RUNTIMEMETRICS_ENABLED, False, origin="unknown")
 
     @classmethod
     def _restart(cls):
@@ -135,7 +139,8 @@ def enable(cls, flush_interval=None, tracer=None, dogstatsd_url=None):
             cls.enabled = True
 
         # Report status to telemetry
-        telemetry.telemetry_writer.add_configuration(TELEMETRY_RUNTIMEMETRICS_ENABLED, True, origin="unknown")
+        if config._telemetry_enabled:
+            telemetry.telemetry_writer.add_configuration(TELEMETRY_RUNTIMEMETRICS_ENABLED, True, origin="unknown")
 
     def flush(self):
         # type: () -> None

releasenotes/notes/fix-telemetry-writer-initialization-163b1effc09d948f.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    telemetry: This fix resolves an issue when using ``pytest`` + ``gevent`` where the telemetry writer was eager initialized by ``pytest`` entrypoints loading of our plugin causing a potential dead lock.

riotfile.py

@@ -2615,6 +2615,7 @@ def select_pys(min_version=MIN_PYTHON_VERSION, max_version=MAX_PYTHON_VERSION):
                 "msgpack": latest,
                 "coverage": latest,
                 "pytest-randomly": latest,
+                "gevent": latest,
             },
         ),
         Venv(