[GitHub] [incubator-shardingsphere] evenardo opened a new pull request #2523: try commit a startup boosted mode and default set to false

[GitBox <gi...@apache.org>]

evenardo opened a new pull request #2523: try commit a startup boosted mode and default set to false
URL: https://github.com/apache/incubator-shardingsphere/pull/2523
 
 
   When we used sharding-jdbc for a development environment , if we have many actual tables, like more than 200 total , it's cost more time to start up the sharding-jdbc .  This may cost several times for developers , especially non-elite programmers for debug process.
   
   I try to found out why this happend , then I try to fix or improve some function especially for dev environment.
   
   I used multi threads to get ready for some map data , really, it's cost more connection database , when sharding-jdbc start up . As @terrymanu  said , it may cause database resources exhausted.
   
   Then I make threads in number of [ sqrt(total actual tables) ], assemby a arraylist to split the slice, into parts of alltableNames, to reduce the threads number , in hope to reduce connection to database.
   
   I collected SQLExceptions , re throw them like origin code to upper logic, but can not throw new exceptions like InterruptedException to upper , because it will change the upper function's "throws" . so I droped them.
   
   why I try to commit a unstable function (or it stable but we don't Long-term tested) , and make a switcher to close this function ?
   
   Because , in our small business, or others like us . Our coder are not elited at all , they cost many many time to restart the local environment to debug ,to change propertitys. So sad , in the waiting time, they are very depressed and complaining complaining ... In our case, it's cost more than 4 minutes :(  in one time. And now it's reduce to 40 seconds , that's within temptation and boost morale !
   
   So I hope is , may officer can make a global switcher in a suitable location to let us set this like a dev frendly mode , to let us boosted the startup process , especially  in a develop environment.
   
   Fixes #ISSUSE_ID.
   
   Changes proposed in this pull request:
   
   in class TableMetaDataInitializer
   
       //Here's a switch to open boosted startup mode;
       //before function integrated into base project,
       //you can rebuild org.apache.shardingsphere.core.execute module,
       //change this to true ,then "mvn clean install" to use this function in your local environment.
       private boolean startUpBoostedMode = false;
   
   in function Map<String, TableMetaData> load(final ShardingRule shardingRule):
   
        if (startUpBoostedMode) {
               System.out.println("org.apache.shardingsphere.core.execute.TableMetaDataInitializer:\n" +
                       "    Beta function warn: Startup boosted mode is friendly for dev mode, " +
                       "but it may cause database resources exhausted. \n" +
                       "    Number of sqrt(number of all actual tables) threads created and finished in process. " +
                       "if error occurs, change to stable mode. \n"+
                       "    Or just use this in your local dev environment. ");
           }

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