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Bug Fix: fix get_instance deadlock and non-atomic ownership acquisition

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If ProxyServer() raises during singleton construction, _instance was left
as _INITIALIZING permanently, causing all subsequent get_instance() callers
to spin in an infinite gevent.sleep() loop. Wrap construction in try/except
and reset _instance to None on failure so callers can retry.

Also replace the non-atomic setnx() + expire() pair in try_acquire_ownership()
with a single atomic SET NX EX call, consistent with the approach already used
in extend_ownership() and eliminating the race window where a crash between the
two calls could leave a key with no TTL (permanent ownership lock).
This commit is contained in:
SergeantPanda 2026-03-03 11:06:52 -06:00
parent 7fed49a334
commit 6d7130d71e
1 changed files with 13 additions and 13 deletions
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26
apps/proxy/ts_proxy/server.py
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@ -43,13 +43,17 @@ class ProxyServer:
return inst
if inst is None:
cls._instance = cls._INITIALIZING
from .server import ProxyServer
from .stream_manager import StreamManager
from .stream_buffer import StreamBuffer
from .client_manager import ClientManager
real_instance = ProxyServer()
cls._instance = real_instance
return real_instance
try:
from .server import ProxyServer
from .stream_manager import StreamManager
from .stream_buffer import StreamBuffer
from .client_manager import ClientManager
real_instance = ProxyServer()
cls._instance = real_instance
return real_instance
except Exception:
cls._instance = None # Reset so next call can retry
raise
# Another greenlet is initializing — wait for completion
while True:
inst = cls._instance
@ -391,20 +395,16 @@ class ProxyServer:
# Create a lock key with proper namespace
lock_key = RedisKeys.channel_owner(channel_id)
# Use Redis SETNX for atomic locking with error handling
# Use atomic SET NX EX for locking with error handling
acquired = self._execute_redis_command(
lambda: self.redis_client.setnx(lock_key, self.worker_id)
lambda: self.redis_client.set(lock_key, self.worker_id, nx=True, ex=ttl)
)
if acquired is None: # Redis command failed
logger.warning(f"Redis command failed during ownership acquisition - assuming ownership")
return True
# If acquired, set expiry to prevent orphaned locks
if acquired:
self._execute_redis_command(
lambda: self.redis_client.expire(lock_key, ttl)
)
logger.info(f"Worker {self.worker_id} acquired ownership of channel {channel_id}")
return True