Connection loss problem

[juklicek]

Hello, we are using stable (6.4) pecl package of your Zookeeper client and we have a issue.
I have a just this simple code:

<?php
$zk = new \Zookeeper("sc1.clapix.com:2181,sc2.clapix.com:2181,sc3.clapix.com:2181/solr");
$zk->setDebugLevel(\Zookeeper::LOG_LEVEL_DEBUG);
$x = $zk->exists('/aliases.json');

var_dump($zk->get('/aliases.json'));

Everything works well till I stop on one of three ZK instance on our servers.

Then I get this sometime:

2019-08-29 16:27:03,228:25057(0x7f2f104b9700):ZOO_DEBUG@get_next_server_in_reconfig@1310: [OLD] count=0 capacity=0 next=0 hasnext=0
2019-08-29 16:27:03,228:25057(0x7f2f104b9700):ZOO_DEBUG@get_next_server_in_reconfig@1313: [NEW] count=3 capacity=16 next=0 hasnext=1
2019-08-29 16:27:03,228:25057(0x7f2f104b9700):ZOO_DEBUG@get_next_server_in_reconfig@1322: Using next from NEW=193.86.66.217:2181
2019-08-29 16:27:03,228:25057(0x7f2f104b9700):ZOO_DEBUG@zookeeper_connect@2210: [zk] connect()

2019-08-29 16:27:03,228:25057(0x7f2f2ccc0880):ZOO_DEBUG@zoo_awexists@3696: Sending request xid=0x5d67e0b8 for path [/aliases.json] to 193.86.66.217:2181
2019-08-29 16:27:03,229:25057(0x7f2f104b9700):ZOO_ERROR@handle_socket_error_msg@2444: Socket [193.86.66.217:2181] zk retcode=-4, errno=111(Connection refused): server refused to accept the client
2019-08-29 16:27:03,229:25057(0x7f2f104b9700):ZOO_DEBUG@cleanup@1763: Previous connection=[193.86.66.217:2181] delay=0
PHP Fatal error:  Uncaught ZookeeperConnectionException: connection loss in /home/jjuklicek/zktest.php:5
Stack trace:
#0 /home/jjuklicek/zktest.php(5): Zookeeper->exists('/aliases.json')
#1 {main}
  thrown in /home/jjuklicek/zktest.php on line 5

Fatal error: Uncaught ZookeeperConnectionException: connection loss in /home/jjuklicek/zktest.php:5
Stack trace:
#0 /home/jjuklicek/zktest.php(5): Zookeeper->exists('/aliases.json')
#1 {main}
  thrown in /home/jjuklicek/zktest.php on line 5
2019-08-29 16:27:03,229:25057(0x7f2f104b9700):ZOO_DEBUG@get_next_server_in_reconfig@1310: [OLD] count=0 capacity=0 next=0 hasnext=0
2019-08-29 16:27:03,230:25057(0x7f2f104b9700):ZOO_DEBUG@get_next_server_in_reconfig@1313: [NEW] count=3 capacity=16 next=1 hasnext=1
2019-08-29 16:27:03,230:25057(0x7f2f104b9700):ZOO_DEBUG@get_next_server_in_reconfig@1322: Using next from NEW=193.86.66.215:2181
2019-08-29 16:27:03,230:25057(0x7f2f104b9700):ZOO_DEBUG@zookeeper_connect@2210: [zk] connect()

2019-08-29 16:27:03,230:25057(0x7f2f104b9700):ZOO_DEBUG@do_io@458: IO thread terminated
2019-08-29 16:27:03,230:25057(0x7f2f0fcb8700):ZOO_DEBUG@do_completion@481: completion thread terminated
2019-08-29 16:27:03,230:25057(0x7f2f2ccc0880):ZOO_INFO@zookeeper_close@3271: Freeing zookeeper resources for sessionId=0

Do you have some idea what is wrong? Is that right that one of three ZK instance failure should be ok for the client?

Thank you very much!

[Timandes]

Sorry for my late reply.
I need some time to reproduce this scenario in order to find some possibilities to this issue.

The following description is WRONG, please ignore it (Edited by Timandes on 2019-9-19):

FYI, Zookeeper::connect() does not actually connect to one of the servers as you call it.
Lazy connection will be established when real needs meet.

[juklicek]

Hallo and thank you. Yes, we would like to know how it was meant and how we should use it correctly?
We find out, that this happen only when first connection is established. When, we are working with existing connection (\Zookeeper instance) it works fine as expected. But, you know how php basically works - everything is established again with every request, so this is not very helpful for us...

[Timandes]

Try this:

<?php

\Zookeeper::setDebugLevel(\Zookeeper::LOG_LEVEL_DEBUG);

// Create instance and register connection callback
$zk = new \Zookeeper("127.0.0.1:2181,127.0.0.2:2182,127.0.0.3:2183",
    function($type, $state) {
        global $zk;
        if ($state == \Zookeeper::CONNECTED_STATE) {
            // We can do other stuff after connection established
            $x = $zk->exists('/aliases.json');
            var_dump($zk->get('/aliases.json'));

            // Stop loop
            exit;
        }
    });

// Loop and dispatch events
while(true) {
    \Zookeeper::dispatch();
    sleep(1);
}