In #3041, a DeprecationWarning is ignored by adding a temporary warning filter and then later using warnings.resetfilters to remove it. However, warnings.resetfilters seems to clear every filters, including the default ones. This means that instrumenting code can enable noisy warning logging that is usually suppressed by default.

There is a context manager that can be used for temporarily changing the warning filters (https://docs.python.org/3/library/warnings.html#warnings.catch_warnings), but its documentation mentions that it is not thread-safe, so it maybe it wouldn't be appropriate for this library...

Describe your environment
Python 3.10, macOS and Linux (via Docker), otel-python v1.15.0 & 0.36b0

Steps to reproduce
Using the example Django app in this repo

1. Modify the view to emit a (normally ignored) warning and to log the current filters

diff --git a/docs/examples/django/pages/views.py b/docs/examples/django/pages/views.py
index e805f4318..8f9e3bdd8 100644
--- a/docs/examples/django/pages/views.py
+++ b/docs/examples/django/pages/views.py
@@ -28,4 +28,8 @@ trace.get_tracer_provider().add_span_processor(


 def home_page_view(request):
+    import warnings
+    warnings.warn("hello", ResourceWarning)
+    print("--- warnings.filters ---")
+    print(warnings.filters)
+    print("------------------------")
     return HttpResponse("Hello, world")

2. Start the server with python manage.py runserver --noreload

3. Open http://127.0.0.1:8000/,

4. Stop the server with ctrl-c

We see the following in the console:

With instrumentation:

...
~/.../opentelemetry-python/docs/examples/django/pages/views.py:32: ResourceWarning: hello
  warnings.warn("hello", ResourceWarning)
--- warnings.filters ---
[]
------------------------
[21/Dec/2022 12:34:56] "GET / HTTP/1.1" 200 12
{
  ... // otel trace
}
^Csys:1: ResourceWarning: unclosed <socket.socket fd=4, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('127.0.0.1', 8000)>
ResourceWarning: Enable tracemalloc to get the object allocation traceback

Without instrumentation (i.e. commenting out DjangoInstrumentor().instrument() in manage.py)

...
--- warnings.filters ---
[('default', None, <class 'DeprecationWarning'>, '__main__', 0), ('ignore', None, <class 'DeprecationWarning'>, None, 0), ('ignore', None, <class 'PendingDeprecationWarning'>, None, 0), ('ignore', None, <class 'ImportWarning'>, None, 0), ('ignore', None, <class 'ResourceWarning'>, None, 0), ('ignore', None, <class 'pkg_resources.PEP440Warning'>, None, 0)]
------------------------
[21/Dec/2022 12:34:56] "GET / HTTP/1.1" 200 12
^C 

Additional context

The default warnings filters are preserved when using versions 1.14.0 and 0.35b0.