Fix SQLite lock errors on /api/stats under concurrent writes.

Retry stats cache commits, serialize refresh, and fall back to read-only compute so the stats API does not return 500 when the database is briefly locked.

Co-authored-by: Cursor <cursoragent@cursor.com>

app.py

@@ -45,7 +45,7 @@ from fee_specs import (
     purge_non_ctp_fee_rates,
 )
 from nav_settings import NAV_TOGGLES, get_nav_items, nav_enabled, save_nav_items
-from stats_engine import STATS_VIEWS, load_stats_cache, refresh_stats_cache
+from stats_engine import STATS_VIEWS, build_all_stats, load_stats_cache, refresh_stats_cache
 from kline_store import ensure_kline_tables
 from kline_stream import kline_hub, sse_format
 from kline_chart import generate_review_kline_chart, fetch_market_klines, MARKET_PERIODS
@@ -230,12 +230,20 @@ def touch_stats_cache():
 
 def get_stats_data() -> dict:
     conn = get_db()
-    capital = float(get_setting("live_capital", "0") or 0)
-    data = load_stats_cache(conn)
-    if not data:
-        data = refresh_stats_cache(conn, capital)
-    conn.close()
-    return data
+    try:
+        capital = float(get_setting("live_capital", "0") or 0)
+        data = load_stats_cache(conn)
+        if data:
+            return data
+        try:
+            return refresh_stats_cache(conn, capital)
+        except sqlite3.OperationalError as exc:
+            if "locked" not in str(exc).lower():
+                raise
+            app.logger.warning("stats cache refresh locked, compute without save: %s", exc)
+            return build_all_stats(conn, capital)
+    finally:
+        conn.close()
 
 
 def init_db():

db_conn.py

@@ -47,3 +47,26 @@ def execute_retry(
     if last_exc:
         raise last_exc
     raise sqlite3.OperationalError("database is locked")
+
+
+def commit_retry(
+    conn: sqlite3.Connection,
+    *,
+    retries: int = 6,
+    base_delay: float = 0.05,
+) -> None:
+    """遇 database is locked 时短暂退避重试 commit。"""
+    last_exc: Exception | None = None
+    for attempt in range(retries):
+        try:
+            conn.commit()
+            return
+        except sqlite3.OperationalError as exc:
+            if "locked" not in str(exc).lower():
+                raise
+            last_exc = exc
+            if attempt < retries - 1:
+                time.sleep(base_delay * (attempt + 1))
+    if last_exc:
+        raise last_exc
+    raise sqlite3.OperationalError("database is locked")

stats_engine.py

@@ -7,11 +7,16 @@
 from __future__ import annotations
 
 import json
+import threading
 from datetime import datetime
 from typing import Any, Optional
 
 from zoneinfo import ZoneInfo
 
+from db_conn import commit_retry, execute_retry
+
+_stats_refresh_lock = threading.Lock()
+
 TZ = ZoneInfo("Asia/Shanghai")
 
 STATS_VIEWS = [
@@ -288,13 +293,14 @@ def build_all_stats(conn, live_capital: float = 0.0) -> dict:
 
 
 def save_stats_cache(conn, data: dict) -> None:
-    conn.execute(
+    execute_retry(
+        conn,
         """INSERT INTO stats_cache (key, data_json, updated_at)
            VALUES ('all', ?, ?)
            ON CONFLICT(key) DO UPDATE SET data_json=excluded.data_json, updated_at=excluded.updated_at""",
         (json.dumps(data, ensure_ascii=False), data["updated_at"]),
     )
-    conn.commit()
+    commit_retry(conn)
 
 
 def load_stats_cache(conn) -> Optional[dict]:
@@ -310,6 +316,7 @@ def load_stats_cache(conn) -> Optional[dict]:
 
 
 def refresh_stats_cache(conn, live_capital: float = 0.0) -> dict:
-    data = build_all_stats(conn, live_capital)
-    save_stats_cache(conn, data)
-    return data
+    with _stats_refresh_lock:
+        data = build_all_stats(conn, live_capital)
+        save_stats_cache(conn, data)
+        return data