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PORedis WATCH MULTI EXEC by one client
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  1. PORedis WATCH MULTI EXEC by one client
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    copied!<p>I am using NodeJS + Express + Redis on RedisOnGo + node_redis as a client. I expect a lot of concurrency, so trying to test WATCH. This example won't contain Express, just necessary stuff.</p> <pre><code>var redis = require("redis") var rc = redis.createClient(config.redis.port, config.redis.host) rc.auth(config.redis.hash, function(err) { if (err) { throw err } }) rc.on('ready', function () { rc.set("inc",0) for(var i=1;i&lt;=10;i++){ rc.watch("inc") rc.get("inc",function(err,data){ var multi = rc.multi() data++ // I do know I can use rc.incr(), this is just for example multi.set("inc",data) multi.exec(function(err,replies){ console.log(replies) }) }) } }) </code></pre> <p><strong>Expecting result</strong>: getting N errors in exec callbacks and finally getting "inc" variable = 10-N.</p> <p><strong>Unexpected result</strong>: getting 0 errors in exec callbacks but finally getting "inc" variable = 1.</p> <p>Watch doesn't work with my code.</p> <p>I have found this thread <a href="https://stackoverflow.com/questions/11832637/redis-and-watch-multi-allows-concurrent-users">redis and watch + multi allows concurrent users</a>. They say it is because of the only redis client.</p> <p>Then I found this thread <a href="https://stackoverflow.com/questions/11009880/should-i-create-a-new-redis-client-for-each-connection">Should I create a new Redis client for each connection?</a>. They say that generating a new client for each transaction "is definitely not recommended". I am lost.</p> <p>Please also note, that I have to authenticate to Redis server. Thanks in advance!</p> <p><strong>EDITION 1:</strong></p> <p>I was able to make it work using local Redis instance (so I do not use client.auth) by creating a new client connection before each WATCH-MULTI-EXEC iteration. Not sure if it is good though, but results now are 100% accurate.</p> <p><strong>EDITION 2</strong> Made it work if I create a new client connection before each WATCH-MULTI-EXEC iteration and then do client.auth and wait for client.on.</p> <p>The question still exists, is it OK that I create new client connections for each iteration?</p>
 

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