refactor(tasks, redis_lock): improve Redis connection and lock handling

- Increased max_connections for Redis pool from 10 to 100.
- Extended socket_timeout from 5 to 10 seconds.
- Added retry mechanism with exponential backoff for Redis operations in `RedisFairLock`.

api/app/tasks.py

@@ -61,9 +61,9 @@ def _get_or_create_redis_pool() -> redis.ConnectionPool | None:
                 db=settings.REDIS_DB_CELERY_BACKEND,
                 password=settings.REDIS_PASSWORD,
                 decode_responses=True,
-                max_connections=10,
+                max_connections=100,
                 socket_connect_timeout=5,
-                socket_timeout=5,
+                socket_timeout=10,
                 retry_on_timeout=True,
                 health_check_interval=30,
             )
@@ -1207,7 +1207,7 @@ def write_message_task(
                     f"- elapsed_time={elapsed_time:.2f}s, task_id={self.request.id}")
 
         try:
-            _r = get_sync_redis_client()
+            _r = redis_client
             if _r is not None:
                 from datetime import timezone as _tz
                 _now_utc = datetime.now(_tz.utc).isoformat()

api/app/utils/redis_lock.py

@@ -1,8 +1,14 @@
+import logging
 import threading
 import time
 import uuid
 
 import redis
+from redis.exceptions import (
+    ConnectionError,
+    TimeoutError,
+    RedisError,
+)
 
 UNLOCK_SCRIPT = """
 if redis.call("get", KEYS[1]) == ARGV[1] then
@@ -68,6 +74,12 @@ def _ensure_str(val):
 class RedisFairLock:
     # ZOMBIE CLEAN BUFFER
     CLEANUP_BUFFER = 30
+    # Redis 操作失败时的最大重试次数
+    MAX_RETRIES = 3
+    # 重试间隔基数（秒），实际间隔 = base * 2^attempt（指数退避）
+    RETRY_BACKOFF_BASE = 0.1
+
+    _logger = logging.getLogger(__name__)
 
     def __init__(
             self,
@@ -90,18 +102,43 @@ class RedisFairLock:
         self._renew_thread = None
         self._stop_renew = threading.Event()
 
+    def _exec_with_retry(self, func, *args, raise_on_fail=True, **kwargs):
+        """
+        带指数退避重试的 Redis 操作执行器。
+
+        对 ConnectionError / TimeoutError 自动重试，其他异常直接抛出。
+        """
+        last_err = None
+        for attempt in range(self.MAX_RETRIES):
+            try:
+                return func(*args, **kwargs)
+            except (ConnectionError, TimeoutError) as e:
+                last_err = e
+                wait = self.RETRY_BACKOFF_BASE * (2 ** attempt)
+                self._logger.warning(
+                    f"[RedisFairLock] Redis error on attempt {attempt + 1}/{self.MAX_RETRIES} "
+                    f"for key={self.key}: {e}, retrying in {wait:.2f}s"
+                )
+                time.sleep(wait)
+            except RedisError:
+                raise
+        if raise_on_fail:
+            raise last_err
+        return None
+
     def acquire(self):
         start = time.time()
 
         while True:
-            ok = self.redis.eval(
+            ok = self._exec_with_retry(
+                self.redis.eval,
                 ACQUIRE_SCRIPT,
                 2,
                 self.queue_key,
                 self.key,
                 self.value,
                 str(self.expire),
-                str(self.timeout + self.CLEANUP_BUFFER)
+                str(self.timeout + self.CLEANUP_BUFFER),
             )
 
             if ok == 1:
@@ -111,7 +148,10 @@ class RedisFairLock:
                 return True
 
             if time.time() - start > self.timeout:
-                self.redis.zrem(self.queue_key,  self.value)
+                self._exec_with_retry(
+                    self.redis.zrem, self.queue_key, self.value,
+                    raise_on_fail=False,
+                )
                 return False
 
             time.sleep(self.retry_interval)
@@ -122,12 +162,14 @@ class RedisFairLock:
             if self._stop_renew.is_set():
                 break
 
-            success = self.redis.eval(
+            success = self._exec_with_retry(
+                self.redis.eval,
                 RENEW_SCRIPT,
                 1,
                 self.key,
                 self.value,
-                str(self.expire)
+                str(self.expire),
+                raise_on_fail=False,
             )
             if not success:
                 break
@@ -149,7 +191,10 @@ class RedisFairLock:
         if self.auto_renewal:
             self._stop_renewal()
 
-        self.redis.eval(UNLOCK_SCRIPT, 1, self.key, self.value)
+        self._exec_with_retry(
+            self.redis.eval, UNLOCK_SCRIPT, 1, self.key, self.value,
+            raise_on_fail=False,
+        )
 
         self._locked = False
 
@@ -161,4 +206,3 @@ class RedisFairLock:
 
     def __exit__(self, exc_type, exc_val, exc_tb):
         self.release()
-