JPA Generate Schema – Scripting was requested, but no target was specified

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Hi all,

I’ve been making some experiments with the Play Framework (version 2.4.2) and JPA integration (with Hibernate – version 4.3.10). I was trying to make Hibernate generate the SQL Schema based on the JPA annotations I had in my entity classes and stumbled upon the error you see on the title, with the following stack trace:

[ProvisionException: Unable to provision, see the following errors: 1) Error injecting constructor, javax.persistence.PersistenceException: Scripting was requested, but no target was specified at play.db.jpa.DefaultJPAApi$JPAApiProvider.<init>(DefaultJPAApi.java:35) at play.db.jpa.DefaultJPAApi$JPAApiProvider.class(DefaultJPAApi.java:30) while locating play.db.jpa.DefaultJPAApi$JPAApiProvider while locating play.db.jpa.JPAApi

I found that there are some JPA properties to make the provider (in my case, Hibernate) generate the scripts for you (standard properties, no need to use hibernate.hbm2ddl.auto in the persistence.xml file). I’ve found that link through this great answer on stackoverflow.

One of the properties is this:

<property name=“javax.persistence.schema-generation.scripts.action” value=“none / drop / drop-and-create / create “/>

Which when I added to my persistence.xml with any of the values – drop/drop-and-create/create  gave me the said error because I didn’t specify where to create the scripts. That’s what the following properties are for:

  • javax.persistence.schema-generation.scripts.create-target
  • javax.persistence.schema-generation.scripts.drop-target

You have to tell the JPA provider where to create the scripts, hence the error “scripting requested, but no target specified“.

The solution

Add the following properties:

  • <property name=“javax.persistence.schema-generation.scripts.action” value=“drop-and-create”/>
  • <property name=“javax.persistence.schema-generation.scripts.drop-target” value=“conf/db/drop-schema.sql”/>
  • <property name=“javax.persistence.schema-generation.scripts.create-target” value=“conf/db/create-schema.sql”/>

You then get the scripts generated to conf/db/. Hope that helps someone 🙂

Happy coding!

MySQL very high CPU usage (and other processes)

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Hi everyone

TL;DR (or Summary) – Leap second added on 30 June 2015 caused MySQL (and other processes to have very high CPU usage)

This is just a quick post on an issue that I faced today (01/07/2015). I arrived at work and found a warning from our monitoring tool that we had high cpu usage beginning at 01.00 AM. On top we saw several processes using a very high amount of CPU, namely:

  • mysql
  • jenkins
  • tomcat
  • ruby (god)
  • ksoftirqd (several of these)

On Tomcat we can have legitimate high cpu usage, but jenkins was not building anything and mysql (version 5.5.31) was not used in anything important. We ran through the logs and analytics to check if we were having an abnormally high visitor access and found nothing, nada, zero. We logged into mysql and issued the SHOW PROCESSLIST command and nothing was happening.

ksoftird was particularly weird, because it is “is a per-cpu kernel thread that runs when the machine is under heavy soft-interrupt load” which didn’t make any sense to us.

What the…. ? (X-Files theme song playing in the background)

After a certain time and more attempts (like trying to use jstack on tomcat to see if it showed anything unusual) we decided to restart mysql, tomcat, jenkins and god, but it all went back again to high cpu usage. We even restarted the server without better luck.

We then read this stack overflow question more carefully and noticed the “leap second issue”, and someone said “hey I remember seeing something about a leap second not to long ago”… I went and check wikipedia, and sure a leap second was added on June 30th 2015.

We tried the following:

$ /etc/init.d/ntpd stop
$ date -s "`date`"
$ /etc/init.d/ntpd start

Some people said that restarting ntp was not required, but… we did it anyway 🙂 And, it worked. Magically everything went back to normal. Apparently we weren’t the only ones affected. I think the next time I see a leap second announcement I’m going to put it on my calendar and warning to a day before 🙂

Mozilla’s blog also documents the issue.

I know this issue is documented, but I wanted to have one more post contributing to people finding this stuff on the internet, could save someone a couple of hours next time.

Happy coding and stay safe of leap seconds!

P.S – Reddit comments over here, Hacker News comments over here

 

I’m going on an adventure

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Me, going on an adventure

Me, going on an adventure

I’ve been developing mostly back-end code for most of my career (Java essentially), I dealt with Java the language, the JVM, Eclipse, Java Enterprise, Databases (Oracle, MySQL, SQL Server), XML, XML Schema, etc… and I did some front-end hacking while developing some of the widgets of the XEO Framework.

I decided that I needed to do something different. I’ve always been fascinated with the front-end world (not necessarily thinking I should have done that all along, I very much like to do back-end code). I’d been reading on all the changes happening in front-end land, such as the MV* frameworks like Angular and Ember, the “recent” appearing of React (and React Native), all the fuss about node.js (io.js), all the tools like bower, gulp, grunt, bootstrap, responsive, rendering performance… a whole new world.

I’ve been fortunate enough to find a new challenge on Memeoirs where I’ve been given the task of managing front-end tasks (including our Ember.JS + EmberCLI application).

What I can say is that it’s been a very humbling experience: In a Java environment I know my way around everything, I know where to search, I’m very productive with Java. On the other hand, working mostly on Javascript for the better part of my day (and using tools like the ember-cli, or having to create my own build process using Broccoli for instance) reminds me that I’m in an incredibly huge field where there is so much stuff that you can do and learn. I’ll still have to learn CSS properly (I hope), responsive design, mockups, even my own text editor changed!

I expect an incredible amount of new things to learn, a lot of walls to bang my head against, but I think It’ll do me very good to have stepped out of my comfort zone and try new things. I believe this knowledge will be very helpful on my future (whatever that may be, because as Steve Jobs said, you can’t connect the dots while looking forward).

Happy coding!