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解决django.db.utils.OperationalError: (1213, 'Deadlock found when trying to get lock; try restarting transaction') 死锁问题

发布时间 2023-07-07 16:52:12作者: 就学45分钟

原因：因为设置了SESSION_SAVE_EVERY_REQUEST=Ture,导致每个接口没有修改的状态下也更改session的过期时间。

  1. 查看代码发现SessionMiddleware源码,遇到UpdateError异常直接抛出。

    try:
    request.session.save()
except UpdateError:
    raise SuspiciousOperation(
        "The request's session was deleted before the "
        "request completed. The user may have logged "
        "out in a concurrent request, for example."
    )

  2. 创建一个新的中间件类，继承自SessionMiddleware

    import time
from django.db import transaction
from django.contrib.sessions.backends.base import UpdateError
from django.contrib.sessions.middleware import SessionMiddleware


class CustomSessionMiddleware(SessionMiddleware):
    # 继承SessionMiddleware 遇到异常重试3次

    def process_response(self, request, response):
        try:
            return super().process_response(request, response)
        except Exception as e:
            print('errors: {}'.format(e))
            max_retries = 3
            retries = 0
            success = False
            while retries < max_retries and not success:
                try:
                    with transaction.atomic():
                        request.session.save()
                    success = True
                except UpdateError:
                    print('试图获得锁时发现死锁;尝试重新启动事务!')
                    retries += 1
                    time.sleep(1)

            if not success:
                # 处理超过最大重试次数的情况
                if request.method == "POST":
                    print(request.body, '================>')
                else:
                    print(request.GET, '================>')
                print('OperationalError 异常已经重试最大次数')
        return response

  3. 在Django的配置文件（settings.py）中将默认的SessionMiddleware替换为自定义的中间件。

    MIDDLEWARE = [
    # 'django.contrib.sessions.middleware.SessionMiddleware',
    # 重写SessionMiddleware
    'middleware.session.CustomSessionMiddleware',
]