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improved tunnel cleanup #706

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improved tunnel cleanup #706

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1ad703e
improved tunnel cleanup
kcoopermiller Jun 2, 2026
521c36d
weakset
kcoopermiller Jun 2, 2026
7784d73
set
kcoopermiller Jun 2, 2026
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23 changes: 23 additions & 0 deletions packages/prime-tunnel/src/prime_tunnel/tunnel.py
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
import asyncio
import atexit
import fcntl
import os
import re
Expand Down Expand Up @@ -29,6 +30,22 @@
)
_ANSI_RE = re.compile(r"\x1b\[[0-9;]*m")

# Started-but-not-stopped tunnels, so an atexit backstop can delete their backend
# registrations if the caller never stops them (forgotten cleanup, unhandled
# exception)
_active_tunnels: "set[Tunnel]" = set()


def _stop_active_tunnels() -> None:
for tunnel in list(_active_tunnels):
try:
tunnel.sync_stop()
except Exception:
pass


atexit.register(_stop_active_tunnels)
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def _parse_frpc_error(
output_lines: list[str],
Expand Down Expand Up @@ -205,6 +222,8 @@ async def start(self) -> str:

self._started = True

_active_tunnels.add(self)

return self.url

async def stop(self) -> None:
Expand All @@ -220,6 +239,8 @@ def sync_stop(self) -> None:
if not self._started:
return

_active_tunnels.discard(self)

if self._process is not None:
try:
self._process.terminate()
Expand Down Expand Up @@ -258,6 +279,8 @@ def sync_stop(self) -> None:

async def _cleanup(self) -> None:
"""Clean up tunnel resources."""
_active_tunnels.discard(self)
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@cursor cursor Bot Jun 2, 2026

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Premature discard defeats atexit backstop on cancellation

Low Severity

_active_tunnels.discard(self) at the top of _cleanup() removes the tunnel from the atexit tracking set before any actual cleanup runs. If the async cleanup is interrupted by CancelledError at an await point (e.g., delete_tunnel or client.close), the error escapes the except Exception handlers (since CancelledError is a BaseException), skipping remaining cleanup steps. Because the tunnel was already discarded, the atexit backstop in _stop_active_tunnels can never retry the incomplete cleanup — defeating its stated purpose of catching "forgotten cleanup" and "unhandled exception" scenarios. Moving the discard to the end of _cleanup() would let the atexit handler pick up partially-cleaned tunnels via sync_stop.

Fix in Cursor Fix in Web

Reviewed by Cursor Bugbot for commit 7784d73. Configure here.


# Stop frpc process (this will cause drain threads to exit via EOF)
if self._process is not None:
try:
Expand Down
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