MySQL连接中断问题分析与解决方案

pymysql.err.OperationalError: (2013, 'Lost connection to MySQL server during query')

-- 查看当前超时设置
SHOW VARIABLES LIKE 'wait_timeout';
SHOW VARIABLES LIKE 'interactive_timeout';

-- 修改超时时间（单位：秒）
SET GLOBAL wait_timeout = 28800;
SET GLOBAL interactive_timeout = 28800;

[mysqld]
wait_timeout = 28800
interactive_timeout = 28800

-- 检查索引情况
EXPLAIN SELECT * FROM user WHERE id = 11;

-- 添加索引（如果缺失）
ALTER TABLE user ADD INDEX idx_id (id);

from sqlalchemy import create_engine
from sqlalchemy.pool import QueuePool

engine = create_engine(
    'mysql+pymysql://user:password@host:3306/db',
    pool_size=10,          # 连接池大小
    max_overflow=5,        # 超出pool_size时允许的临时连接
    pool_recycle=3600,     # 1小时后回收连接，避免被MySQL关闭
    pool_pre_ping=True,    # 执行前检查连接是否有效
    pool_timeout=30        # 获取连接的超时时间（秒）
)

from sqlalchemy.exc import OperationalError
import time

def execute_with_retry(session, query, max_retries=3, retry_delay=1):
    for attempt in range(max_retries):
        try:
            result = session.execute(query)
            return result
        except OperationalError as e:
            if attempt == max_retries - 1:
                raise  # 重试次数用尽，抛出异常
            time.sleep(retry_delay)
            continue

# prometheus.yml 配置示例
scrape_configs:
  - job_name: 'mysql'
    static_configs:
      - targets: ['mysql-exporter:9104']

-- 优化表结构
OPTIMIZE TABLE user;

-- 定期清理无用连接
KILL IDLE CONNECTION <process_id>;

from flask import Flask, jsonify
import sqlalchemy

app = Flask(__name__)

@app.route('/health')
def health_check():
    try:
        with engine.connect() as conn:
            conn.execute("SELECT 1")
        return jsonify({"status": "healthy"})
    except sqlalchemy.exc.OperationalError:
        return jsonify({"status": "unhealthy"}), 500