fix(tests): use get_context('fork') instead of set_start_method to avoid global state conflict

Author: sterchelen

opentelemetry-sdk/tests/metrics/test_meter_provider_fork.py

@@ -17,13 +17,11 @@
 import multiprocessing
 import os
 import unittest
-from platform import system
 
 from opentelemetry.sdk.metrics import MeterProvider
 from opentelemetry.sdk.resources import Resource
 
-if system() != "Windows":
-    multiprocessing.set_start_method("fork", force=True)
+_fork_ctx = multiprocessing.get_context("fork") if hasattr(os, "fork") else None
 
 
 @unittest.skipUnless(
@@ -83,8 +81,8 @@ def child(conn):
             conn.send(child_id)
             conn.close()
 
-        parent_conn, child_conn = multiprocessing.Pipe()
-        process = multiprocessing.Process(target=child, args=(child_conn,))
+        parent_conn, child_conn = _fork_ctx.Pipe()
+        process = _fork_ctx.Process(target=child, args=(child_conn,))
         process.start()
         child_id = parent_conn.recv()
         process.join()
@@ -109,8 +107,8 @@ def child(conn):
         conns = []
 
         for _ in range(4):
-            parent_conn, child_conn = multiprocessing.Pipe()
-            process = multiprocessing.Process(
+            parent_conn, child_conn = _fork_ctx.Pipe()
+            process = _fork_ctx.Process(
                 target=child, args=(child_conn,)
             )
             processes.append(process)

opentelemetry-sdk/tests/trace/test_tracer_provider_fork.py

@@ -17,13 +17,11 @@
 import multiprocessing
 import os
 import unittest
-from platform import system
 
 from opentelemetry.sdk.resources import Resource
 from opentelemetry.sdk.trace import TracerProvider
 
-if system() != "Windows":
-    multiprocessing.set_start_method("fork", force=True)
+_fork_ctx = multiprocessing.get_context("fork") if hasattr(os, "fork") else None
 
 
 @unittest.skipUnless(
@@ -75,8 +73,8 @@ def child(conn):
             conn.send(child_id)
             conn.close()
 
-        parent_conn, child_conn = multiprocessing.Pipe()
-        process = multiprocessing.Process(target=child, args=(child_conn,))
+        parent_conn, child_conn = _fork_ctx.Pipe()
+        process = _fork_ctx.Process(target=child, args=(child_conn,))
         process.start()
         child_id = parent_conn.recv()
         process.join()
@@ -100,8 +98,8 @@ def child(conn):
         conns = []
 
         for _ in range(4):
-            parent_conn, child_conn = multiprocessing.Pipe()
-            process = multiprocessing.Process(
+            parent_conn, child_conn = _fork_ctx.Pipe()
+            process = _fork_ctx.Process(
                 target=child, args=(child_conn,)
             )
             processes.append(process)