本篇文章給大家?guī)淼膬?nèi)容是關(guān)于如何實(shí)現(xiàn)python3實(shí)現(xiàn)并發(fā)訪問水平切分表，有一定的參考價(jià)值，有需要的朋友可以參考一下，希望對你有所幫助。

場景說明

假設(shè)有一個(gè)mysql表被水平切分，分散到多個(gè)host中，每個(gè)host擁有n個(gè)切分表。

如果需要并發(fā)去訪問這些表，快速得到查詢結(jié)果， 應(yīng)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(shí)現(xiàn)這個(gè)需求。

代碼演示

import logging

import random

import asynciofrom aiomysql

import create_pool

# 假設(shè)mysql表分散在8個(gè)host, 每個(gè)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(xù)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(shù)，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(shí)際的sql訪問處理函數(shù)，通過aiomysql實(shí)現(xiàn)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(duì)列, 隊(duì)列的每個(gè)元素包含要對某個(gè)表進(jìn)行訪問的函數(shù)及參數(shù)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(yùn)行sql訪問請求隊(duì)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(shí)現(xiàn)函數(shù)異步調(diào)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()

總結(jié)

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