fix: Fix memory leak in PlaywrightCrawler on browser context creation (#1446)

### Description

- Add `Lock` to `PlaywrightBrowserController._browser_context` creation
to ensure no orphaned duplicate contexts are created.


### Issues

- Closes: #1443

### Testing

- Unit test added.
- Benchmark actor with PlaywrightCrawler used to confirm normal memory
consumption with this fix.

Author: Pijukatel

src/crawlee/browsers/_playwright_browser_controller.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+from asyncio import Lock
 from datetime import datetime, timedelta, timezone
 from typing import TYPE_CHECKING, Any, cast
 
@@ -77,6 +78,19 @@ def __init__(
 
         self._total_opened_pages = 0
 
+        self._context_creation_lock: Lock | None = None
+
+    async def _get_context_creation_lock(self) -> Lock:
+        """Get context checking and creation lock.
+
+        It should be done with lock to prevent multiple concurrent attempts to create context, which could lead to
+        memory leak as one of the two concurrently created contexts will become orphaned and not properly closed.
+        """
+        if self._context_creation_lock:
+            return self._context_creation_lock
+        self._context_creation_lock = Lock()
+        return self._context_creation_lock
+
     @property
     @override
     def pages(self) -> list[Page]:
@@ -137,12 +151,6 @@ async def new_page(
         Raises:
             ValueError: If the browser has reached the maximum number of open pages.
         """
-        if not self._browser_context:
-            self._browser_context = await self._create_browser_context(
-                browser_new_context_options=browser_new_context_options,
-                proxy_info=proxy_info,
-            )
-
         if not self.has_free_capacity:
             raise ValueError('Cannot open more pages in this browser.')
 
@@ -154,11 +162,12 @@ async def new_page(
             )
             page = await new_context.new_page()
         else:
-            if not self._browser_context:
-                self._browser_context = await self._create_browser_context(
-                    browser_new_context_options=browser_new_context_options,
-                    proxy_info=proxy_info,
-                )
+            async with await self._get_context_creation_lock():
+                if not self._browser_context:
+                    self._browser_context = await self._create_browser_context(
+                        browser_new_context_options=browser_new_context_options,
+                        proxy_info=proxy_info,
+                    )
             page = await self._browser_context.new_page()
 
         # Handle page close event
@@ -169,7 +178,6 @@ async def new_page(
         self._last_page_opened_at = datetime.now(timezone.utc)
 
         self._total_opened_pages += 1
-
         return page
 
     @override
@@ -206,7 +214,6 @@ async def _create_browser_context(
         `self._fingerprint_generator` is available.
         """
         browser_new_context_options = dict(browser_new_context_options) if browser_new_context_options else {}
-
         if proxy_info:
             if browser_new_context_options.get('proxy'):
                 logger.warning("browser_new_context_options['proxy'] overriden by explicit `proxy_info` argument.")
@@ -244,5 +251,4 @@ async def _create_browser_context(
         browser_new_context_options['extra_http_headers'] = browser_new_context_options.get(
             'extra_http_headers', extra_http_headers
         )
-
         return await self._browser.new_context(**browser_new_context_options)

tests/unit/browsers/test_playwright_browser_controller.py

@@ -2,12 +2,13 @@
 
 import asyncio
 from datetime import datetime, timedelta, timezone
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Any
+from unittest.mock import AsyncMock
 
 import pytest
 from playwright.async_api import Browser, Playwright, async_playwright
 
-from crawlee.browsers import PlaywrightBrowserController
+from crawlee.browsers import PlaywrightBrowserController, PlaywrightPersistentBrowser
 
 if TYPE_CHECKING:
     from collections.abc import AsyncGenerator
@@ -106,3 +107,28 @@ async def test_close_browser_with_open_pages(browser: Browser) -> None:
 
     assert controller.pages_count == 0
     assert not controller.is_browser_connected
+
+
+async def test_memory_leak_on_concurrent_context_creation() -> None:
+    """Test that only one browser context is created when multiple pages are opened concurrently."""
+
+    # Prepare mocked browser with relevant methods and attributes
+    mocked_browser = AsyncMock()
+    mocked_context_launcher = AsyncMock()
+
+    async def delayed_launch_persistent_context(*args: Any, **kwargs: Any) -> Any:
+        """Ensure that both calls to create context overlap in time."""
+        await asyncio.sleep(5)  # Simulate delay in creation to make sure race condition happens
+        return await mocked_context_launcher(*args, **kwargs)
+
+    mocked_browser.launch_persistent_context = delayed_launch_persistent_context
+
+    # Create minimal instance of PlaywrightBrowserController with mocked browser
+    controller = PlaywrightBrowserController(
+        PlaywrightPersistentBrowser(mocked_browser, None, {}), header_generator=None, fingerprint_generator=None
+    )
+
+    # Both calls will try to create browser context at the same time, but only one context should be created.
+    await asyncio.gather(controller.new_page(), controller.new_page())
+
+    assert mocked_context_launcher.call_count == 1