Prevent recursive logging issue in SimpleLogRecordProcessor.on_emit

CHANGELOG.md

@@ -13,13 +13,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## Unreleased
 
 - `opentelemetry-sdk`: Fix the type hint of the `_metrics_data` property to allow `None`
-  ([#4837](https://github.com/open-telemetry/opentelemetry-python/pull/4837)
+  ([#4837](https://github.com/open-telemetry/opentelemetry-python/pull/4837)).
 - Regenerate opentelemetry-proto code with v1.9.0 release
   ([#4840](https://github.com/open-telemetry/opentelemetry-python/pull/4840))
 - Add python 3.14 support
   ([#4798](https://github.com/open-telemetry/opentelemetry-python/pull/4798))
 - Silence events API warnings for internal users
   ([#4847](https://github.com/open-telemetry/opentelemetry-python/pull/4847))
+- Prevent possible endless recursion from happening in `SimpleLogRecordProcessor.on_emit`,
+  ([#4799](https://github.com/open-telemetry/opentelemetry-python/pull/4799)).
 
 ## Version 1.39.0/0.60b0 (2025-12-03)
 

opentelemetry-api/test-requirements.txt

@@ -12,5 +12,5 @@ wrapt==1.16.0
 zipp==3.20.2
 -e opentelemetry-sdk
 -e opentelemetry-semantic-conventions
--e tests/opentelemetry-test-utils
 -e opentelemetry-api
+-e tests/opentelemetry-test-utils

opentelemetry-sdk/src/opentelemetry/sdk/_logs/_internal/export/__init__.py

@@ -17,6 +17,7 @@
 import enum
 import logging
 import sys
+import traceback
 from os import environ, linesep
 from typing import IO, Callable, Optional, Sequence
 
@@ -52,6 +53,9 @@
 _logger = logging.getLogger(__name__)
 _logger.addFilter(DuplicateFilter())
 
+_propagate_false_logger = logging.getLogger(__name__ + ".propagate.false")
+_propagate_false_logger.propagate = False
+
 
 class LogRecordExportResult(enum.Enum):
     SUCCESS = 0
@@ -145,11 +149,33 @@ def __init__(self, exporter: LogRecordExporter):
         self._shutdown = False
 
     def on_emit(self, log_record: ReadWriteLogRecord):
-        if self._shutdown:
-            _logger.warning("Processor is already shutdown, ignoring call")
+        # Prevent entering a recursive loop.
+        if (
+            sum(
+                item.name == "on_emit"
+                and (
+                    item.filename.endswith("export/__init__.py")
+                    or item.filename.endswith(
+                        r"export\__init__.py"
+                    )  # backward slash on windows..
+                )
+                for item in traceback.extract_stack()
+            )
+            # Recursive depth of 3 is sort of arbitrary. It's possible that an Exporter.export call
+            # emits a log which returns us to this function, but when we call Exporter.export again the log
+            # is no longer emitted and we exit this recursive loop naturally, a depth of >3 allows 3
+            # recursive log calls but exits after because it's likely endless.
+            > 3
+        ):
+            _propagate_false_logger.warning(
+                "SimpleLogRecordProcessor.on_emit has entered a recursive loop. Dropping log and exiting the loop."
+            )
             return
         token = attach(set_value(_SUPPRESS_INSTRUMENTATION_KEY, True))
         try:
+            if self._shutdown:
+                _logger.warning("Processor is already shutdown, ignoring call")
+                return
             # Convert ReadWriteLogRecord to ReadableLogRecord before exporting
             # Note: resource should not be None at this point as it's set during Logger.emit()
             resource = (
@@ -166,7 +192,8 @@ def on_emit(self, log_record: ReadWriteLogRecord):
             self._exporter.export((readable_log_record,))
         except Exception:  # pylint: disable=broad-exception-caught
             _logger.exception("Exception while exporting logs.")
-        detach(token)
+        finally:
+            detach(token)
 
     def shutdown(self):
         self._shutdown = True

opentelemetry-sdk/src/opentelemetry/sdk/_shared_internal/__init__.py

@@ -42,8 +42,8 @@
 class DuplicateFilter(logging.Filter):
     """Filter that can be applied to internal `logger`'s.
 
-    Currently applied to `logger`s on the export logs path that could otherwise cause endless logging of errors or a
-    recursion depth exceeded issue in cases where logging itself results in an exception."""
+    Currently applied to `logger`s on the export logs path to prevent endlessly logging the same log
+    in cases where logging itself is failing."""
 
     def filter(self, record):
         current_log = (
@@ -81,6 +81,10 @@ def shutdown(self):
         raise NotImplementedError
 
 
+_logger = logging.getLogger(__name__)
+_logger.addFilter(DuplicateFilter())
+
+
 class BatchProcessor(Generic[Telemetry]):
     """This class can be used with exporter's that implement the above
     Exporter interface to buffer and send telemetry in batch through
@@ -111,8 +115,6 @@ def __init__(
             target=self.worker,
             daemon=True,
         )
-        self._logger = logging.getLogger(__name__)
-        self._logger.addFilter(DuplicateFilter())
         self._exporting = exporting
 
         self._shutdown = False
@@ -189,20 +191,20 @@ def _export(self, batch_strategy: BatchExportStrategy) -> None:
                         ]
                     )
                 except Exception:  # pylint: disable=broad-exception-caught
-                    self._logger.exception(
+                    _logger.exception(
                         "Exception while exporting %s.", self._exporting
                     )
                 detach(token)
 
-    # Do not add any logging.log statements to this function, they can be being routed back to this `emit` function,
-    # resulting in endless recursive calls that crash the program.
-    # See https://github.com/open-telemetry/opentelemetry-python/issues/4261
     def emit(self, data: Telemetry) -> None:
         if self._shutdown:
+            _logger.info("Shutdown called, ignoring %s.", self._exporting)
             return
         if self._pid != os.getpid():
             self._bsp_reset_once.do_once(self._at_fork_reinit)
-        # This will drop a log from the right side if the queue is at _max_queue_length.
+        if len(self._queue) == self._max_queue_size:
+            _logger.warning("Queue full, dropping %s.", self._exporting)
+        # This will drop a log from the right side if the queue is at _max_queue_size.
         self._queue.appendleft(data)
         if len(self._queue) >= self._max_export_batch_size:
             self._worker_awaken.set()

opentelemetry-sdk/test-requirements.txt

@@ -11,7 +11,7 @@ tomli==2.0.1
 typing_extensions==4.10.0
 wrapt==1.16.0
 zipp==3.19.2
--e tests/opentelemetry-test-utils
 -e opentelemetry-api
+-e tests/opentelemetry-test-utils
 -e opentelemetry-semantic-conventions
 -e opentelemetry-sdk

opentelemetry-sdk/tests/logs/test_export.py

@@ -15,12 +15,13 @@
 # pylint: disable=protected-access
 import logging
 import os
+import sys
 import time
 import unittest
 from concurrent.futures import (  # pylint: disable=no-name-in-module
     ThreadPoolExecutor,
 )
-from sys import version_info
+from typing import Sequence
 from unittest.mock import Mock, patch
 
 from pytest import mark
@@ -38,6 +39,7 @@
     BatchLogRecordProcessor,
     ConsoleLogRecordExporter,
     InMemoryLogRecordExporter,
+    LogRecordExporter,
     SimpleLogRecordProcessor,
 )
 from opentelemetry.sdk.environment_variables import (
@@ -63,6 +65,46 @@
 
 
 class TestSimpleLogRecordProcessor(unittest.TestCase):
+    @mark.skipif(
+        (3, 13, 0) <= sys.version_info <= (3, 13, 5),
+        reason="This will fail on 3.13.5 due to https://github.com/python/cpython/pull/131812 which prevents recursive log messages but was rolled back in 3.13.6.",
+    )
+    def test_simple_log_record_processor_doesnt_enter_recursive_loop(self):
+        class Exporter(LogRecordExporter):
+            def shutdown(self):
+                pass
+
+            def export(self, batch: Sequence[ReadableLogRecord]):
+                logger = logging.getLogger("any logger..")
+                logger.warning("Something happened.")
+
+        exporter = Exporter()
+        logger_provider = LoggerProvider()
+        logger_provider.add_log_record_processor(
+            SimpleLogRecordProcessor(exporter)
+        )
+        root_logger = logging.getLogger()
+        # Add the OTLP handler to the root logger like is done in auto instrumentation.
+        # This causes logs generated from within SimpleLogRecordProcessor.on_emit (such as the above log in export)
+        # to be sent back to SimpleLogRecordProcessor.on_emit
+        handler = LoggingHandler(
+            level=logging.DEBUG, logger_provider=logger_provider
+        )
+        root_logger.addHandler(handler)
+        propagate_false_logger = logging.getLogger(
+            "opentelemetry.sdk._logs._internal.export.propagate.false"
+        )
+        # This would cause a max recursion depth exceeded error..
+        try:
+            with self.assertLogs(propagate_false_logger) as cm:
+                root_logger.warning("hello!")
+            assert (
+                "SimpleLogRecordProcessor.on_emit has entered a recursive loop"
+                in cm.output[0]
+            )
+        finally:
+            root_logger.removeHandler(handler)
+
     def test_simple_log_record_processor_default_level(self):
         exporter = InMemoryLogRecordExporter()
         logger_provider = LoggerProvider()
@@ -406,39 +448,6 @@ def bulk_emit(num_emit):
         time.sleep(2)
         assert len(exporter.get_finished_logs()) == total_expected_logs
 
-    @mark.skipif(
-        version_info < (3, 10),
-        reason="assertNoLogs only exists in python 3.10+.",
-    )
-    def test_logging_lib_not_invoked_in_batch_log_record_emit(self):  # pylint: disable=no-self-use
-        # See https://github.com/open-telemetry/opentelemetry-python/issues/4261
-        exporter = Mock()
-        processor = BatchLogRecordProcessor(exporter)
-        logger_provider = LoggerProvider(
-            resource=SDKResource.create(
-                {
-                    "service.name": "shoppingcart",
-                    "service.instance.id": "instance-12",
-                }
-            ),
-        )
-        logger_provider.add_log_record_processor(processor)
-        handler = LoggingHandler(
-            level=logging.INFO, logger_provider=logger_provider
-        )
-        sdk_logger = logging.getLogger("opentelemetry.sdk")
-        # Attach OTLP handler to SDK logger
-        sdk_logger.addHandler(handler)
-        # If `emit` calls logging.log then this test will throw a maximum recursion depth exceeded exception and fail.
-        try:
-            with self.assertNoLogs(sdk_logger, logging.NOTSET):
-                processor.on_emit(EMPTY_LOG)
-            processor.shutdown()
-            with self.assertNoLogs(sdk_logger, logging.NOTSET):
-                processor.on_emit(EMPTY_LOG)
-        finally:
-            sdk_logger.removeHandler(handler)
-
     def test_args(self):
         exporter = InMemoryLogRecordExporter()
         log_record_processor = BatchLogRecordProcessor(