赵凡导师并发知识第一次分享观后感
主要是渗透了解 asyncio 相关概念
提及部分描述：1.线程（阻塞，非阻塞）
2.线程之间通信（线程之间的传递（import queue））
3.进程之间通信（进程之间通信from multiprocessing import Process,Queue 用进程Queue）单独详解
）
举例图：
场景描述：
数据库的要操作的表的信息为：
当多个请求都到数据库操作接口程序的时候，针对同一个name的count进行增加或者减少，就要保证操作的同一个时刻只有一个可以去获取count的值并进行update操作，所以我是在这一步增加了锁，因为使用aiohttp写的，所以想要在这里也用了aiorwlock，但是在我测试的过程中发现了，当一个协程获取锁还没释放锁的时候，另外一个协程也获取到锁，下面我是具体的代码
核心程序：
class CntHandler(object): def __init__(self, db, loop): self.db = db self.loop = loop self.company_lock = {} def response(self, request, msg): peer = request.transport.get_extra_info('peername') logging.info("request url[%s] from[%s]: %s", request.raw_path, peer, msg) origin = request.headers.get("Origin") if origin is not None: headers = {"Access-Control-Allow-Origin": origin, "Access-Control-Allow-Credentials": "true"} resp = web.Response(text=util.dictToJson(msg), content_type='application/json', headers=headers) else: resp = web.Response(text=util.dictToJson(msg), content_type='application/json') return resp async def cnt_set(self, request): """ 用于设置company表中的count值 :param request: :return: """ post = await request.post() logging.info('post %s', post) company_name = post.get("company") cnt = post.get("cnt") sql = "update shield.company set count=%s where name=%s" args_values = [cnt, company_name] rwlock = self.company_lock.get(company_name, "") if not rwlock: rwlock = aiorwlock.RWLock(loop=self.loop) self.company_lock[company_name] = rwlock async with rwlock.writer: msg = dict() po_sql = "select * from shield.company where name=%s" po = await self.db.get(po_sql, company_name) if not po: # 找不到企业 logging.error("not found company name [%s]", company_name) msg["code"] = 404 msg["code"] = "not found company" return self.response(request, msg) res = await self.db.execute(sql, args_values) if not isinstance(res, int): logging.error("sql update is err:", res) msg["code"] = 403 msg["reason"] = "set fail" return self.response(request, msg) logging.info("company [%s] set cnt [%s] is success", company_name, cnt) msg["code"] = 200 msg["reason"] = "ok" return self.response(request, msg) async def cnt_inc(self, request): """ 用于增加company表中的count值 :param request: :return: """ post = await request.post() logging.info('post %s', post) company_name = post.get("company") cnt = int(post.get("cnt", 0)) rwlock = self.company_lock.get(company_name, "") if not rwlock: rwlock = aiorwlock.RWLock(loop=self.loop) self.company_lock[company_name] = rwlock async with rwlock.writer: uuid_s = uuid.uuid1().hex logging.debug("[%s]---[%s]", uuid_s, id(rwlock)) msg = dict() sql = "select * from shield.company where name=%s" po = await self.db.get(sql, company_name) if not po: # 找不到企业 logging.error("not found company name [%s]", company_name) msg["code"] = 404 msg["code"] = "not found company" return self.response(request, msg) old_cnt = po.get("count") po_cnt = int(po.get("count")) res = po_cnt + cnt update_sql = "update shield.company set count=%s where name=%s" args_values = [res, company_name] update_res = await self.db.execute(update_sql, args_values) if not isinstance(update_res, int): # 数据库update失败 logging.error("sql update is err:", update_res) msg["code"] = 403 msg["reason"] = "inc fail" return self.response(request, msg) logging.info("uuid [%s] lock [%s] company [%s] inc cnt [%s] old cnt [%s] true will is [%s] success", uuid_s,id(rwlock), company_name, cnt, old_cnt, res) msg["code"] = 200 msg["reason"] = "ok" return self.response(request, msg) async def cnt_dec(self, request): """ 用于减少company表中count的值 :param request: :return: """ post = await request.post() logging.info('post %s', post) company_name = post.get("company") cnt = int(post.get("cnt", 0)) rwlock = self.company_lock.get(company_name, "") if not rwlock: rwlock = aiorwlock.RWLock(loop=self.loop) self.company_lock[company_name] = rwlock async with rwlock.writer: uuid_s = uuid.uuid1().hex logging.debug("[%s]---[%s]", uuid_s, id(rwlock)) msg = dict() sql = "select * from shield.company where name=%s" po = await self.db.get(sql, company_name) if not po: # 找不到企业 logging.error("not found company name [%s]", company_name) msg["code"] = 404 msg["code"] = "not found company" return self.response(request, msg) po_cnt = int(po.get("count")) old_cnt = po.get("count") if po_cnt == 0: logging.error("company [%s] cnt is 0", company_name) msg["code"] = 400 msg["reason"] = "cnt is 0" return self.response(request, msg) if po_cnt < cnt: # 数据库余额不足 logging.error("company [%s] count is not enough", company_name) msg["code"] = 405 msg["reason"] = "count is not enough" return self.response(request, msg) res = po_cnt - cnt update_sql = "update shield.company set count=%s where name=%s" args_values = [res, company_name] update_res = await self.db.execute(update_sql, args_values) if not isinstance(update_res, int): # 执行update 失败 logging.error("sql update is err:", update_res) msg["code"] = 403 msg["reason"] = "inc fail" return self.response(request, msg) logging.info("uuid [%s] lock [%s] company [%s] dec cnt [%s] old cnt [%s] true will is [%s] success",uuid_s,id(rwlock), company_name, cnt, old_cnt, res) msg["code"] = 200 msg["reason"] = "ok" return self.response(request, msg)
上面代码出问题的代码是在增加和减少的时候：
async with rwlock.writer:
