mirror of
https://github.com/NousResearch/hermes-agent.git
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1cec5c69d3
The salvaged unit tests hand-construct completed futures to lock the _run_on_mcp_loop contract. Add a live-loop test that reproduces the actual field trigger: an inner asyncio.wait_for expiry stores a real TimeoutError on a real future scheduled on the MCP loop. Asserts the fixed loop surfaces it once, promptly -- not spinning to the outer deadline (which both leaked memory and masked the real error behind the generic wrapper message).
68 lines
2.6 KiB
Python
68 lines
2.6 KiB
Python
"""End-to-end coverage for the MCP poll-loop OOM spin (#63892).
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The unit tests in ``test_mcp_tool.py`` hand-construct completed futures to lock
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the ``_run_on_mcp_loop`` contract deterministically. This complements them by
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exercising the actual field trigger through the *live* MCP loop: an inner
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``asyncio.wait_for`` expiry produces a real ``TimeoutError`` stored on a real
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future scheduled via ``run_coroutine_threadsafe``. On Python >= 3.8 that class
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is the builtin ``TimeoutError``, so before the fix the poll loop swallowed the
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completed future's stored exception and spun with no sleep -- burning CPU,
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growing the exception traceback ~108 MB/s until the gateway OOM'd, and finally
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masking the real error behind the generic "MCP call timed out after <full
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timeout>" wrapper.
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The fixed loop must surface the real exception once, promptly -- long before
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the outer deadline.
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"""
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from __future__ import annotations
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import asyncio
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import time
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import pytest
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@pytest.fixture
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def mcp_loop():
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import tools.mcp_tool as mcp_tool
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mcp_tool._ensure_mcp_loop()
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yield mcp_tool
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mcp_tool._stop_mcp_loop()
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def test_inner_wait_for_timeout_surfaces_promptly_without_spinning(mcp_loop):
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async def inner():
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# Real TimeoutError from wait_for, completing far before the outer
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# deadline below -- the exact shape of an MCP call_tool wrapped in the
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# server's configured mcp_servers.<srv>.timeout.
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await asyncio.wait_for(asyncio.sleep(60), timeout=0.05)
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start = time.monotonic()
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with pytest.raises(TimeoutError) as exc:
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mcp_loop._run_on_mcp_loop(inner, timeout=10)
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elapsed = time.monotonic() - start
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# Fixed: the real inner TimeoutError surfaces within a couple poll ticks.
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# Broken: the loop swallows it and spins with no sleep until the 10s
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# deadline, then raises the generic wrapper message instead. A generous
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# (>= 2s) bound keeps this stable on a slow CI runner while still failing
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# hard on a spin-to-deadline regression.
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assert elapsed < 5.0, (
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f"poll loop spun for {elapsed:.1f}s instead of resolving the completed "
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"future once (#63892 regression)"
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)
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assert "MCP call timed out after" not in str(exc.value), (
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"the real inner TimeoutError must surface, not the outer poll deadline"
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)
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def test_successful_call_still_returns_through_real_loop(mcp_loop):
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"""Guard the done-future path against regressing normal success returns."""
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async def inner():
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await asyncio.sleep(0.25) # first polls time out while still pending
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return {"ok": True}
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assert mcp_loop._run_on_mcp_loop(inner, timeout=10) == {"ok": True}
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