Overturn common sense-dead loop structure code, also has the opportunity to execute the logic outside the loop

Disruption to common sense-the code of the endless loop structure also has the opportunity to execute the logic outside the loop & lt ;? Php & nbsp; class & nbsp; ZookeeperDemo & nbsp; extends & nbsp; Zookeeper & nbsp ;{& nbsp; & nbsp; public knowledge-dead loop structure code, it also has the opportunity to execute non-circular logic
 
Class ZookeeperDemo extends Zookeeper {
 
Public function watcher ($ I, $ type, $ key ){
Echo "Insider Watcher \ n ";
 
// Watcher gets consumed so we need to set a new one
$ This-> get ('/test', array ($ this, 'Watcher '));
}
 
}
 
$ Zoo = new ZookeeperDemo ('2017. 0.0.1: 100 ');
$ Zoo-> get ('/test', array ($ zoo, 'Watcher '));
 
While (true ){
Echo '.';
Sleep (2 );
}


Run the script now.

$ Php zookeeperdemo1.php
A vertex is generated every 2 seconds. Switch to the ZooKeeper client and update the "/test" value.

[Zk: 127.0.0.1: 2181 (CONNECTED) 20] set/test foo
This will silently trigger the "Insider Watcher" message in the PHP script.


How can this happen? Why can I execute the watcher method after entering the while structure. Please read the official discussion.


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Distributed applications?
ZooKeeper is a distributed, open-source distributed application coordination service that contains a simple primitive set and is an important component of Hadoop and Hbase. Currently, Java and C interfaces are provided.

It is understandable that you say it is a common sense of disruption.
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Watcher gets consumed so we need to set a new one
You should be more aware of this than I do.

Php Zookeeper is always listening for php behavior
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Isn't it normal that the subthread continues to execute tasks in an endless loop of the main thread?
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There is a pcntl in php that can fork multiple processes for execution.