Refactor RequestGenerator to use threading and update test suite

Refactored RequestGenerator class:
- Replaced asyncio.Queue with Queue from the queue module for thread safety.
- Utilized threading for background queue population to ensure non-blocking request generation.
- Removed the start method as threading automatically starts the background task in async mode.
- Ensured that the _populate_queue method runs in a background thread to keep the queue populated.
- Implemented clean shutdown with the stop method joining the background thread.
Updated unit tests:
- Added test_request_generator_sync_constructor and test_request_generator_async_constructor to verify constructor behavior.
- Added tests for __repr__ and __iter__ methods.
- Added tests to ensure create_item raises NotImplementedError if not overridden.
- Added tests to verify __iter__ calls create_item the expected number of times.

Separated test files:
- Created tests/unit/request/test_base.py for unit tests.
- Created tests/integration/request/test_base.py for integration tests.

Unit tests:
- Verified the construction of the class with different input parameters.
- Mocked AutoTokenizer for testing tokenizer initialization with both a class implementation and a string alias.
- Ensured that the __iter__ method works correctly in both sync and async modes.
- Verified that create_item is called the expected number of times.

Integration tests:
- Tested tokenizer construction with both a Hugging Face tokenizer and a string alias, ensuring the correct tokenizer is created.

src/guidellm/request/base.py

@@ -1,5 +1,7 @@
-import asyncio
+import threading
+import time
 from abc import ABC, abstractmethod
+from queue import Empty, Full, Queue
 from typing import Iterator, Optional, Union
 
 from loguru import logger
@@ -31,20 +33,29 @@ def __init__(
     ):
         self._async_queue_size = async_queue_size
         self._mode = mode
-        self._queue = asyncio.Queue(maxsize=async_queue_size)
-        self._stop_event = asyncio.Event()
+        self._queue = Queue(maxsize=async_queue_size)
+        self._stop_event = threading.Event()
 
         if tokenizer is not None:
             self._tokenizer = (
                 AutoTokenizer.from_pretrained(tokenizer)
                 if isinstance(tokenizer, str)
                 else tokenizer
             )
-            logger.info(f"Tokenizer initialized: {self._tokenizer}")
+            logger.info("Tokenizer initialized: {}", self._tokenizer)
         else:
             self._tokenizer = None
             logger.debug("No tokenizer provided")
 
+        if self._mode == "async":
+            self._thread = threading.Thread(target=self._populate_queue)
+            self._thread.daemon = True
+            self._thread.start()
+            logger.info(
+                "RequestGenerator started in async mode with queue size: {}",
+                self._async_queue_size,
+            )
+
     def __repr__(self) -> str:
         """
         Return a string representation of the RequestGenerator.
@@ -72,7 +83,7 @@ def __iter__(self) -> Iterator[TextGenerationRequest]:
                     item = self._queue.get_nowait()
                     self._queue.task_done()
                     yield item
-                except asyncio.QueueEmpty:
+                except Empty:
                     continue
         else:
             while not self._stop_event.is_set():
@@ -118,46 +129,31 @@ def create_item(self) -> TextGenerationRequest:
         """
         raise NotImplementedError()
 
-    def start(self):
-        """
-        Start the background task that populates the queue.
-        """
-        if self.mode == "async":
-            try:
-                loop = asyncio.get_running_loop()
-                logger.info("Using existing event loop")
-            except RuntimeError:
-                raise RuntimeError("No running event loop found for async mode")
-
-            loop.call_soon_threadsafe(
-                lambda: asyncio.create_task(self._populate_queue())
-            )
-            logger.info(
-                f"RequestGenerator started in async mode with queue size: "
-                f"{self._async_queue_size}"
-            )
-        else:
-            logger.info("RequestGenerator started in sync mode")
-
     def stop(self):
         """
         Stop the background task that populates the queue.
         """
         logger.info("Stopping RequestGenerator...")
         self._stop_event.set()
+        if self._mode == "async":
+            self._thread.join()
         logger.info("RequestGenerator stopped")
 
-    async def _populate_queue(self):
+    def _populate_queue(self):
         """
         Populate the request queue in the background.
         """
         while not self._stop_event.is_set():
-            if self._queue.qsize() < self._async_queue_size:
-                item = self.create_item()
-                await self._queue.put(item)
-                logger.debug(
-                    f"Item added to queue. Current queue size: {self._queue.qsize()}"
-                )
-            else:
-                await asyncio.sleep(0.1)
+            try:
+                if self._queue.qsize() < self._async_queue_size:
+                    item = self.create_item()
+                    self._queue.put(item, timeout=0.1)
+                    logger.debug(
+                        "Item added to queue. Current queue size: {}",
+                        self._queue.qsize(),
+                    )
+                else:
+                    time.sleep(0.1)
+            except Full:
+                continue
         logger.info("RequestGenerator stopped populating queue")

tests/integration/request/test_base.py

@@ -0,0 +1,23 @@
+import pytest
+from transformers import AutoTokenizer, PreTrainedTokenizerBase
+from guidellm.core.request import TextGenerationRequest
+from guidellm.request.base import RequestGenerator
+
+
+class TestRequestGenerator(RequestGenerator):
+    def create_item(self) -> TextGenerationRequest:
+        return TextGenerationRequest(prompt="Test prompt")
+
+
+@pytest.mark.smoke
+def test_request_generator_with_hf_tokenizer():
+    tokenizer = AutoTokenizer.from_pretrained("bert-base-uncased")
+    generator = TestRequestGenerator(tokenizer=tokenizer)
+    assert generator.tokenizer == tokenizer
+
+
+@pytest.mark.smoke
+def test_request_generator_with_string_tokenizer():
+    generator = TestRequestGenerator(tokenizer="bert-base-uncased")
+    assert isinstance(generator.tokenizer, PreTrainedTokenizerBase)
+    assert generator.tokenizer.name_or_path == "bert-base-uncased"

tests/unit/request/test_base.py

@@ -1,3 +1,5 @@
+from unittest.mock import Mock, patch
+
 import pytest
 
 from guidellm.core.request import TextGenerationRequest
@@ -10,15 +12,28 @@ def create_item(self) -> TextGenerationRequest:
 
 
 @pytest.mark.smoke
-def test_request_generator_sync():
+def test_request_generator_sync_constructor():
     generator = TestRequestGenerator(mode="sync")
     assert generator.mode == "sync"
+    assert generator.async_queue_size == 50  # Default value
     assert generator.tokenizer is None
 
+
+@pytest.mark.smoke
+def test_request_generator_async_constructor():
+    generator = TestRequestGenerator(mode="async", async_queue_size=10)
+    assert generator.mode == "async"
+    assert generator.async_queue_size == 10
+    assert generator.tokenizer is None
+    generator.stop()
+
+
+@pytest.mark.smoke
+def test_request_generator_sync_iter():
+    generator = TestRequestGenerator(mode="sync")
     items = []
     for item in generator:
         items.append(item)
-
         if len(items) == 5:
             break
 
@@ -27,28 +42,30 @@ def test_request_generator_sync():
 
 
 @pytest.mark.smoke
-@pytest.mark.asyncio
-def test_request_generator_async():
-    generator = TestRequestGenerator(mode="async", async_queue_size=10)
-    assert generator.mode == "async"
-    assert generator.async_queue_size == 10
-    assert generator.tokenizer is None
-
-    generator.start()
-
+def test_request_generator_async_iter():
+    generator = TestRequestGenerator(mode="async")
     items = []
     for item in generator:
         items.append(item)
-
         if len(items) == 5:
             break
 
     generator.stop()
-    assert generator._stop_event.is_set()
-
     assert len(items) == 5
     assert items[0].prompt == "Test prompt"
-    assert items[-1].prompt == "Test prompt"
+
+
+@pytest.mark.regression
+def test_request_generator_with_mock_tokenizer():
+    mock_tokenizer = Mock()
+    generator = TestRequestGenerator(tokenizer=mock_tokenizer)
+    assert generator.tokenizer == mock_tokenizer
+
+    with patch("guidellm.request.base.AutoTokenizer") as MockAutoTokenizer:
+        MockAutoTokenizer.from_pretrained.return_value = mock_tokenizer
+        generator = TestRequestGenerator(tokenizer="mock-tokenizer")
+        assert generator.tokenizer == mock_tokenizer
+        MockAutoTokenizer.from_pretrained.assert_called_with("mock-tokenizer")
 
 
 @pytest.mark.regression
@@ -57,3 +74,55 @@ def test_request_generator_repr():
     assert repr(generator) == (
         "RequestGenerator(mode=sync, async_queue_size=100, tokenizer=None)"
     )
+
+
+@pytest.mark.regression
+def test_request_generator_create_item_not_implemented():
+    with pytest.raises(TypeError):
+        class IncompleteRequestGenerator(RequestGenerator):
+            pass
+
+        IncompleteRequestGenerator()
+
+    class IncompleteCreateItemGenerator(RequestGenerator):
+        def create_item(self):
+            super().create_item()
+
+    generator = IncompleteCreateItemGenerator()
+    with pytest.raises(NotImplementedError):
+        generator.create_item()
+
+
+@pytest.mark.regression
+def test_request_generator_iter_calls_create_item():
+    generator = TestRequestGenerator(mode="sync")
+    generator.create_item = Mock(
+        return_value=TextGenerationRequest(prompt="Mock prompt")
+    )
+
+    items = []
+    for item in generator:
+        items.append(item)
+        if len(items) == 5:
+            break
+
+    assert len(items) == 5
+    generator.create_item.assert_called()
+
+
+@pytest.mark.regression
+def test_request_generator_async_iter_calls_create_item():
+    generator = TestRequestGenerator(mode="sync")
+    generator.create_item = Mock(
+        return_value=TextGenerationRequest(prompt="Mock prompt")
+    )
+
+    items = []
+    for item in generator:
+        items.append(item)
+        if len(items) == 5:
+            break
+
+    generator.stop()
+    assert len(items) == 5
+    generator.create_item.assert_called()