revert: 移除 CONN_HEALTH_CHECKS（远程库每条请求多打一次 SQL）；加可选慢请求追踪

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

a_long_dianjing/settings.py

@@ -56,6 +56,7 @@ MIDDLEWARE = [
     'django.contrib.auth.middleware.AuthenticationMiddleware',
     'django.contrib.messages.middleware.MessageMiddleware',
     'django.middleware.clickjacking.XFrameOptionsMiddleware',
+    'utils.slow_request_middleware.SlowRequestTraceMiddleware',
 ]
 
 # 日志配置 — 500 错误堆栈输出到 console，受 DEBUG_DETAIL_LOG 开关控制
@@ -126,7 +127,6 @@ DATABASES = {
         'PASSWORD': app_secrets.DATABASE_PASSWORD,
         'PORT': app_secrets.DATABASE_PORT,
         'CONN_MAX_AGE': 600,
-        'CONN_HEALTH_CHECKS': True,
         'OPTIONS': {
             'charset': 'utf8mb4',
             'init_command': "SET time_zone='+08:00'",

deploy/apply-lag-fix.sh

@@ -16,14 +16,6 @@ sleep 2
 systemctl is-active gunicorn-dianjing.service
 pgrep -cf 'gunicorn.*a_long_dianjing' || true
 
-echo ""
-echo ">>> 安装 worker 保活 cron（空闲后不卡）"
-chmod +x deploy/gunicorn-warmup.sh
-cp deploy/gunicorn-warmup.cron /etc/cron.d/gunicorn-warmup
-chmod 644 /etc/cron.d/gunicorn-warmup
-bash deploy/gunicorn-warmup.sh
-echo "  cron 已安装，每2分钟预热 worker"
-
 echo ""
 echo ">>> 最近慢请求 (rt>=0.5s):"
 grep -a 'hqhd' "$NGINX_LOG" | awk 'match($0,/rt=([0-9.]+)/,a){if(a[1]+0>=0.5)print}' | tail -5

deploy/disable-slow-trace.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+# 关闭慢请求追踪
+rm -f /etc/systemd/system/gunicorn-dianjing.service.d/slow-trace.conf
+systemctl daemon-reload
+systemctl restart gunicorn-dianjing.service
+echo "慢请求追踪已关闭"

deploy/enable-slow-trace.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+# 开启慢请求追踪（只写日志，不改业务逻辑）。卡的时候跑这个，操作小程序，再 cat 日志。
+set -e
+SVC=/etc/systemd/system/gunicorn-dianjing.service
+mkdir -p /etc/systemd/system/gunicorn-dianjing.service.d
+cat > /etc/systemd/system/gunicorn-dianjing.service.d/slow-trace.conf <<'EOF'
+[Service]
+Environment=SLOW_REQUEST_TRACE=1
+Environment=SLOW_REQUEST_THRESHOLD_MS=200
+Environment=SLOW_REQUEST_LOG=/tmp/slow-request-trace.log
+EOF
+: > /tmp/slow-request-trace.log
+systemctl daemon-reload
+systemctl restart gunicorn-dianjing.service
+echo "已开启。现在去小程序复现卡顿，然后执行:"
+echo "  cat /tmp/slow-request-trace.log"
+echo "关闭: bash deploy/disable-slow-trace.sh"

utils/slow_request_middleware.py

@@ -0,0 +1,47 @@
+"""
+可选：慢请求追踪（默认关闭，不影响现网）。
+启用: 在 gunicorn systemd 的 Environment 加 SLOW_REQUEST_TRACE=1 后 restart。
+日志: /tmp/slow-request-trace.log
+"""
+import logging
+import os
+import time
+
+logger = logging.getLogger('slow_request')
+
+_ENABLED = os.environ.get('SLOW_REQUEST_TRACE', '').strip() in ('1', 'true', 'yes')
+_THRESHOLD_MS = float(os.environ.get('SLOW_REQUEST_THRESHOLD_MS', '300'))
+_LOG_PATH = os.environ.get('SLOW_REQUEST_LOG', '/tmp/slow-request-trace.log')
+
+
+class SlowRequestTraceMiddleware:
+    def __init__(self, get_response):
+        self.get_response = get_response
+
+    def __call__(self, request):
+        if not _ENABLED:
+            return self.get_response(request)
+
+        t0 = time.perf_counter()
+        from django.db import connection, reset_queries
+        reset_queries()
+        response = self.get_response(request)
+        elapsed_ms = (time.perf_counter() - t0) * 1000
+
+        if elapsed_ms >= _THRESHOLD_MS:
+            n_sql = len(connection.queries)
+            sql_ms = sum(float(q.get('time', 0)) for q in connection.queries) * 1000
+            line = (
+                f"{elapsed_ms:.0f}ms total | sql={n_sql}条/{sql_ms:.0f}ms | "
+                f"{request.method} {request.path} | status={response.status_code}\n"
+            )
+            try:
+                with open(_LOG_PATH, 'a', encoding='utf-8') as f:
+                    f.write(line)
+                    if n_sql <= 30:
+                        for q in sorted(connection.queries, key=lambda x: -float(x.get('time', 0)))[:5]:
+                            sql = q['sql'][:200].replace('\n', ' ')
+                            f.write(f"  {float(q['time'])*1000:.0f}ms {sql}\n")
+            except OSError:
+                logger.warning('slow request trace write failed')
+        return response