Python 基于python操纵zookeeper介绍

授客

发布于 2019-09-10 18:31:46

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发布于 2019-09-10 18:31:46

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测试环境

Win7 64位

Python 3.3.4

kazoo-2.6.1-py2.py3-none-any.whl（windows）

kazoo-2.6.1.tar.gz (linux)

https://pypi.org/project/kazoo/#files

zookeeper-3.4.13.tar.gz

下载地址：

http://zookeeper.apache.org/releases.html#download

https://www.apache.org/dyn/closer.cgi/zookeeper/

https://mirrors.tuna.tsinghua.edu.cn/apache/zookeeper/

代码实践

kazooStudy.py

#!/usr/bin/env python 3.4.0

#-*- encoding:utf-8 -*-

__author__ = 'shouke'

import threading

import time

from kazoo.client import KazooClient

from kazoo.client import KazooState

from kazoo.retry import KazooRetry

def restart_zk_client():

'''重启zookeeper会话'''

global zk_client

global zk_conn_stat

try:

zk_client.restart()

except Exception as e:

print('重启zookeeper客户端异常：%s' % e)

zk_conn_stat = 0 # zookeeper连接状态 1-LOST 2-SUSPENDED 3-CONNECTED/RECONNECTED

def zk_conn_listener(state):

'''zookeeper连接状态监听器'''

global zk_conn_stat

if state == KazooState.LOST:

print('zookeeper connection lost')

zk_conn_stat = 1

# Register somewhere that the session was lost

thread = threading.Thread(target=restart_zk_client)

thread.start()

elif state == KazooState.SUSPENDED:

print('zookeeper connection dicconnected')

zk_conn_stat = 2

# Handle being disconnected from Zookeeper

else:

zk_conn_stat = 3

print('zookeeper connection cconnected/reconnected')

# Handle being connected/reconnected to Zookeeper

# 监视器

# 当节点有变化、节点被删除时，将以多线程的方式调用以参数形式传递给get()、exists()的监视函数，监视函数将会接收到一个WatchedEvent实例

def event_listener(event):

print(event)

if __name__ == '__main__':

try:

# 建立连接

zk_client = KazooClient(hosts='127.0.0.1:2181')

zk_client.add_listener(zk_conn_listener) # 添加监听器，监听连接状态

zk_client.start() # 初始化到zk的连接，可以设置超时时间 zk_client.start(timeout=15) 默认15秒

print('zk_client state：', zk_client.state) # 查看链接状态

# 创建节点

# ensure_path() 递归创建path中不存在的节点，但是不能为节点设置数据，仅ACL.

zk_client.ensure_path('/node1')

# 创建永久节点

# create创建节点的同时，可为节点设置数据，要求path路径必须存在

if not zk_client.exists('/node1/subNode1'):

zk_client.create('/node1/subNode1', b'sub node1')

# 创建临时节点

# 注意：会话丢失、重启会话会导致zookeeper删除重启会话前创建的临时节点

if not zk_client.exists('/node1/subNode2'):

zk_client.create('/node1/subNode2', b'sub node2', ephemeral=True)

# 创建有序临时节点

zk_client.create('/node1/subNode', b'sub nodexxxx', ephemeral=True, sequence=True)

# 读取数据

# 判断节点是否存在

if zk_client.exists('/node1'): # 如果返回值为None则表示不存在给定节点

print('存在节点node1,节点路径/node1')

# 获取节点相关数据

data, stat = zk_client.get('/node1')

if stat:

print("Version: %s, data: %s" % (stat.version, data.decode("utf-8")))

# 获取给定节点的子节点

children = zk_client.get_children('/node1')

print('node1子节点有 %s 子节点，节点名称为: %s' % (len(children), children))

print('/ 子节点', zk_client.get_children('/'))

# 更新节点

# 更新节点数据

zk_client.set("/node1/subNode2", b"some new data")

# 删除节点 recursive参数可选，递归删除节点数据

zk_client.delete("/node1", recursive=True)

# 重试命令

try:

result = zk_client.retry(zk_client.get, "/node1/subNode3")

print(result)

# 自定义重试

# max_tries 出错最大重试次数， ignore_expire False-重试的时候忽略会话过期，否则不忽略

kr = KazooRetry(max_tries=3, ignore_expire=False)

result = kr(zk_client.get, "/node1/subNode3")

except Exception as e:

print('/node1/subNode3 不存在，所以会运行出错')

# 释放客户端占用资源，移除连接

zk_client.stop()

# zk_client.stop() 会导致zk_client连接状态变成 LOST，进而触发线程调用函数 restart_zk_client，

# 该函数未执行完成的情况下，如果马上执行类似get,create等函数，会导致运行出错

while zk_conn_stat != 3:

continue

else:

i = 0

while i < 3000:

if i % 200 == 0:

time.sleep(2)

print('创建新节点')

zk_client.ensure_path('/node1')

zk_client.ensure_path('/node1/subNode2')

zk_client.create('/node1/subNode', b'sub nodexxxx', ephemeral=True, sequence=True)

zk_client.set('/node1/subNode2', b'new data')

i += 1

# 关闭客户端前必须先调用stop,否则会报错

zk_client.stop()

# 关闭客户端

zk_client.close()

except Exception as e:

print('运行出错：%s' % e)

monitor.py

#!/usr/bin/env python

#-*- encoding:utf-8 -*-

__author__ = 'shouke'

import time

from kazoo.client import KazooClient

from kazoo.client import KazooState

zk = KazooClient(hosts='10.118.52.26:2181')

zk.start()

@zk.add_listener

def my_listener(state):

if state == KazooState.LOST:

print('LOST')

# Register somewhere that the session was lost

elif state == KazooState.SUSPENDED:

print('SUSPENDED')

# Handle being disconnected from Zookeeper

else:

pass

print('CONNECTED')

# Handle being connected/reconnected to Zookeeper

# 监视器

# 当节点有变化、节点被删除时，将以多线程的方式调用以参数形式传递给get()、exists()的监视函数，监视函数将会接收到一个WatchedEvent实例

def event_listener(event):

print(event)

children = zk.get_children('/node1',watch=event_listener)

print('node1 has %s children with names %s' % (len(children), children))

# 更高级监视api

# 监视子节点的编号

@zk.ChildrenWatch('/node1')

def watch_children(children):

print("Children are now: %s" % children)

# 监视节点数据变更

@zk.DataWatch("/node1/subNode2") #

def watch_node(data, state):

"""监视节点数据是否变化"""

if state:

print("Version:", state.version, "data:", data)

# 空转

i = 0

while i< 100:

# children = zk.get_children('/node1',watch=event_listener)

# print('node1 has %s children with names %s' % (len(children), children))

time.sleep(1)

zk.stop()

zk.close()

关于kazooClient连接状态说明

LOST

CONNECTED

SUSPENDED

KazooClient客户端实例刚创建时，处于LOST状态，同zookeeper建立连接后，转为CONNECTED 。如果连接出问题、切换到不同的zookeeper集群几点，转为SUSPENDED状态，当你知道暂时不能执行命令，如果zookeeper节点不再是集群的一部分，连接将丢失，也会导致 SUSPENDED状态

客户端再次同zookeeper建立连接，如果会话不存在，客户端连接状态将转为LOST，如果会话没有过期，可用则转为CONNECTED