Stop multiple calls to AsyncPGInstrumentor.__init__ from clobbering instance attributes

CHANGELOG.md

@@ -11,6 +11,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#2151](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2151))
 - `opentelemetry-resource-detector-azure` Added 10s timeout to VM Resource Detector
   ([#2119](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2119))
+- `opentelemetry-instrumentation-asyncpg` Allow AsyncPGInstrumentor to be instantiated multiple times
+([#1791](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1791))
 - `opentelemetry-instrumentation-confluent-kafka` Add support for higher versions until 2.3.0 of confluent_kafka
   ([#2132](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/2132))
 - `opentelemetry-resource-detector-azure` Changed timeout to 4 seconds due to [timeout bug](https://github.com/open-telemetry/opentelemetry-python/issues/3644)

instrumentation/opentelemetry-instrumentation-asyncpg/src/opentelemetry/instrumentation/asyncpg/__init__.py

@@ -96,11 +96,13 @@ def _hydrate_span_from_args(connection, query, parameters) -> dict:
 
 
 class AsyncPGInstrumentor(BaseInstrumentor):
+
+    _leading_comment_remover = re.compile(r"^/\*.*?\*/")
+    _tracer = None
+
     def __init__(self, capture_parameters=False):
         super().__init__()
         self.capture_parameters = capture_parameters
-        self._tracer = None
-        self._leading_comment_remover = re.compile(r"^/\*.*?\*/")
 
     def instrumentation_dependencies(self) -> Collection[str]:
         return _instruments

instrumentation/opentelemetry-instrumentation-asyncpg/tests/test_asyncpg_wrapper.py

@@ -5,7 +5,7 @@
 
 
 class TestAsyncPGInstrumentation(TestBase):
-    def test_duplicated_instrumentation(self):
+    def test_duplicated_instrumentation_can_be_uninstrumented(self):
         AsyncPGInstrumentor().instrument()
         AsyncPGInstrumentor().instrument()
         AsyncPGInstrumentor().instrument()
@@ -16,6 +16,14 @@ def test_duplicated_instrumentation(self):
                 hasattr(method, "_opentelemetry_ext_asyncpg_applied")
             )
 
+    def test_duplicated_instrumentation_works(self):
+        first = AsyncPGInstrumentor()
+        first.instrument()
+        second = AsyncPGInstrumentor()
+        second.instrument()
+        self.assertIsNotNone(first._tracer)
+        self.assertIsNotNone(second._tracer)
+
     def test_duplicated_uninstrumentation(self):
         AsyncPGInstrumentor().instrument()
         AsyncPGInstrumentor().uninstrument()