python zookeeper watch 事件

from kazoo.client import KazooClient

from kazoo.client import KazooState 

import time

print time.ctime()

zk = KazooClient(hosts='20.5.101.15:12181',timeout=500,read_only=True)

print zk

print zk.state

zk.start()

if zk.exists('/sds'):

  print '111111111'

else:

  print '222222222'

print zk.get_children('/consumers')

# print zk.get('/aaayyy')

# zk.set("/aaayyy", b"some data")

# print zk.get('/aaayyy')

def my_func(event):

  print "abcdefg"

while True:

  time.sleep(1)

  children=zk.get_children("/consumers",watch=my_func)

  print children 
 

C:\Python27\python.exe C:/Users/tlcb/PycharmProjects/untitled/rizhiyi/t3.py

Thu Jun 21 15:21:44 2018



LOST

222222222

[u'console-consumer-48493', u'console-consumer-63948']

[u'console-consumer-48493', u'console-consumer-63948']

[u'console-consumer-48493', u'console-consumer-63948']

[u'console-consumer-48493', u'console-consumer-63948']

[u'console-consumer-48493', u'console-consumer-63948']

[u'console-consumer-48493', u'console-consumer-63948']

[u'console-consumer-48493', u'console-consumer-63948']

[u'console-consumer-48493', u'console-consumer-63948']

[u'console-consumer-48493', u'console-consumer-63948']

[u'console-consumer-48493', u'console-consumer-63948']

[u'console-consumer-48493', u'console-consumer-63948']

[u'console-consumer-48493', u'console-consumer-63948']

abcdefg

[u'console-consumer-48493']

[u'console-consumer-48493']

[u'console-consumer-48493']

[u'console-consumer-48493'] 

Process finished with exit code 1 
 

测试环境；

[root@elkapp05 bin]# ./kafka-console-consumer.sh --zookeeper 20.5.101.15:12181 --topic shuaige --from-beginning

Using the ConsoleConsumer with old consumer is deprecated and will be removed in a future major release. Consider using the new consumer by passing [bootstrap-server] instead of [zookeeper]. 
 
[root@elkapp05 bin]# ./kafka-console-consumer.sh --zookeeper 20.5.101.15:12181 --topic shuaige --from-beginning

Using the ConsoleConsumer with old consumer is deprecated and will be removed in a future major release. Consider using the new consumer by passing [bootstrap-server] instead of [zookeeper].

111

222222222

fdfdfd

dsadsadasd

888888888

565

fdfd

4324

3242

342

4

2432

5454

54

5

5

^CProcessed a total of 16 messages 

当一个消费者断开后触发事件


Kazoo 可以设置watch 函数在几个节点,可以被触发当节点改变或者当子节点改变



这个对节点或者子节点改变可以是节点或者子节点被删除


Watchers 可以设置两种不同的方式,第一种是Zookeeper 默认支持一次性watch events.

这些watch 函数可以通过kazoo调用,不接收session events

不像本地的Zookeeper watches.  使用这个需要watch 函数被传递到下面方法里:

get()
get_children()
exists()


一个watch 函数传递到get()或者exists 会被调用当数据节点在节点或者子节点本身被删除

它会被传递到一个 WatchedEvent instance.

def my_func(event):
    # check to see what the children are now

# Call my_func when the children change
children = zk.get_children("/my/favorite/node", watch=my_func)

Kazoo 包含一个更高级别的API用于watch 数据和子节点修改

是更容易使用因为它不需要重新设置watch 每次 当事件触发时。

它也传递数据和ZnodeStat 当watch一个节点或者子节点列表 

watch 函数会被调用当每次有改变时

或直到函数返回False

如果 allow_session_lost是设置为True  那么函数不会被调用 当session 是丢失

下面的方法提供这个功能: