場景說明

假設有一個mysql表被水平切分，分散到多個host中，每個host擁有n個切分表。

如果需要并發去訪問這些表，快速得到查詢結果， 應該怎么做呢？

這里提供一種方案，利用python3的asyncio異步io庫及aiomysql異步庫去實現這個需求。

代碼演示

import loggingimport randomimport asynciofrom aiomysql import create_pool# 假設mysql表分散在8個host, 每個host有16張子表TBLES = {  "192.168.1.01": "table_000-015",# 000-015表示該ip下的表明從table_000一直連續到table_015  "192.168.1.02": "table_016-031",    "192.168.1.03": "table_032-047",      "192.168.1.04": "table_048-063",      "192.168.1.05": "table_064-079",       "192.168.1.06": "table_080-095",       "192.168.1.07": "table_096-0111",        "192.168.1.08": "table_112-0127",}USER = "xxx"PASSWD = "xxxx"# wrapper函數，用于捕捉異常def query_wrapper(func):  async def wrapper(*args, **kwargs):    try:      await func(*args, **kwargs)    except Exception as e:      print(e)  return wrapper      # 實際的sql訪問處理函數，通過aiomysql實現異步非阻塞請求@      query_wrapperasync def query_do_something(ip, db, table):  async with create_pool(host=ip, db=db, user=USER, password=PASSWD) as pool:    async with pool.get() as conn:      async with conn.cursor() as cur:        sql = ("select xxx from {} where xxxx")        await cur.execute(sql.format(table))        res = await cur.fetchall()     # then do something...# 生成sql訪問隊列, 隊列的每個元素包含要對某個表進行訪問的函數及參數def gen_tasks():  tasks = []  for ip, tbls in TBLES.items():    cols = re.split('_|-', tbls)    tblpre = "_".join(cols[:-2])    min_num = int(cols[-2])    max_num = int(cols[-1])         for num in range(min_num, max_num+1):      tasks.append(        (query_do_something, ip, 'your_dbname', '{}_{}'.format(tblpre, num))      )   random.shuffle(tasks)     return tasks# 按批量運行sql訪問請求隊列def run_tasks(tasks, batch_len):  try:      for idx in range(0, len(tasks), batch_len):      batch_tasks = tasks[idx:idx+batch_len]      logging.info("current batch, start_idx:%s len:%s" % (idx, len(batch_tasks)))             for i in range(0, len(batch_tasks)):        l = batch_tasks[i]        batch_tasks[i] = asyncio.ensure_future(          l[0](*l[1:])        )      loop.run_until_complete(asyncio.gather(*batch_tasks))        except Exception as e:    logging.warn(e)# main方法, 通過asyncio實現函數異步調用def main():  loop = asyncio.get_event_loop()   tasks = gen_tasks()  batch_len = len(TBLES.keys()) * 5  # all up to you  run_tasks(tasks, batch_len)   loop.close()

以上就是本次相關內容的全部實例代碼，大家可以本地測試以下，感謝你對武林站長站的支持。