Fix issue with Flask instrumentation when a request spawn children th…

…reads and copie the request context

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

@@ -38,43 +38,38 @@
 
     FlaskInstrumentor().instrument(enable_commenter=True, commenter_options={})
 
-For example, FlaskInstrumentor when used with SQLAlchemyInstrumentor or Psycopg2Instrumentor,
-invoking ``cursor.execute("select * from auth_users")`` will lead to sql query
-``select * from auth_users`` but when SQLCommenter is enabled the query will get appended with
-some configurable tags like:
 
-.. code::
+For example,
+::
 
-    select * from auth_users /*metrics=value*/;"
+   FlaskInstrumentor when used with SQLAlchemyInstrumentor or Psycopg2Instrumentor, invoking cursor.execute("select * from auth_users")
+   will lead to sql query "select * from auth_users" but when SQLCommenter is enabled
+   the query will get appended with some configurable tags like "select * from auth_users /*metrics=value*/;"
 
-Inorder for the commenter to append flask related tags to sql queries, the commenter needs
-to enabled on the respective SQLAlchemyInstrumentor or Psycopg2Instrumentor framework too.
+    Inorder for the commenter to append flask related tags to sql queries, the commenter needs to enabled on
+    the respective  SQLAlchemyInstrumentor or Psycopg2Instrumentor framework too.
 
 SQLCommenter Configurations
 ***************************
-We can configure the tags to be appended to the sqlquery log by adding configuration
-inside ``commenter_options={}`` dict.
-
-For example, enabling this flag will add flask and it's version which
-is ``/*flask%%3A2.9.3*/`` to the SQL query as a comment (default is True):
-
-.. code:: python
-
-    framework = True
+We can configure the tags to be appended to the sqlquery log by adding configuration inside commenter_options(default:{}) keyword
 
-For example, enabling this flag will add route uri ``/*route='/home'*/``
-to the SQL query as a comment (default is True):
+framework = True(Default) or False
 
-.. code:: python
+For example,
+::
+Enabling this flag will add flask and it's version which is /*flask%%3A2.9.3*/
 
-    route = True
+route = True(Default) or False
 
-For example, enabling this flag will add controller name ``/*controller='home_view'*/``
-to the SQL query as a comment (default is True):
+For example,
+::
+Enabling this flag will add route uri /*route='/home'*/
 
-.. code:: python
+controller = True(Default) or False
 
-    controller = True
+For example,
+::
+Enabling this flag will add controller name /*controller='home_view'*/
 
 Usage
 -----
@@ -238,10 +233,10 @@ def response_hook(span: Span, status: str, response_headers: List):
 API
 ---
 """
-
 from logging import getLogger
 from time import time_ns
 from timeit import default_timer
+from threading import get_ident
 from typing import Collection
 
 import flask
@@ -397,7 +392,7 @@ def _before_request():
 
         activation = trace.use_span(span, end_on_exit=True)
         activation.__enter__()  # pylint: disable=E1101
-        flask_request_environ[_ENVIRON_ACTIVATION_KEY] = activation
+        flask_request_environ[_ENVIRON_ACTIVATION_KEY] = (get_ident(), activation)
         flask_request_environ[_ENVIRON_SPAN_KEY] = span
         flask_request_environ[_ENVIRON_TOKEN] = token
 
@@ -436,8 +431,8 @@ def _teardown_request(exc):
         if excluded_urls and excluded_urls.url_disabled(flask.request.url):
             return
 
-        activation = flask.request.environ.get(_ENVIRON_ACTIVATION_KEY)
-        if not activation:
+        thread_id, activation = flask.request.environ.get(_ENVIRON_ACTIVATION_KEY)
+        if not activation or thread_id != get_ident():
             # This request didn't start a span, maybe because it was created in
             # a way that doesn't run `before_request`, like when it is created
             # with `app.test_request_context`.
@@ -456,6 +451,7 @@ def _teardown_request(exc):
 
 
 class _InstrumentedFlask(flask.Flask):
+
     _excluded_urls = None
     _tracer_provider = None
     _request_hook = None