docs: Improve Examples

[cseewald]

I am currently incorporating DB-Scheduler into a project I am working on (10000 onetimetasks processed per hour in an Oracle database). Thanks for your awesome work!!

I decided to contribute something very modest back.

Changes

• Removed ExampleHelpers.java: method sleep was unused, method registerShutdownHook is replaced by registerShutdownHook in SchedulerBuilder
• Add missing main method in RecurringTaskMain.java

Reminders

• [-] Added/ran automated tests
• [-] Update README and/or examples
• Ran mvn spotless:apply

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cc @kagkarlsson

[kagkarlsson]

Excellent! Thank you for contributing! 🙏

[kagkarlsson]

Btw this PR might be of interest to you as well. It will introduce explicit LIMIT in the fetch-query for all databases.

#371

[kagkarlsson]

Thank you for cleaning up the examples! 🙏

[cseewald]

Btw this PR might be of interest to you as well. It will introduce explicit LIMIT in the fetch-query for all databases.

#371

Yes, I will probably update when it it is part of a release: To make sure the existing db-scheduler version actually works with many 1000 rows in the task table I did a test with huge task data and many 1000 rows within a highly memory constraint JVM. The java.sql.Statement#setMaxRows already seems to do a good enough job to only fetch the limited number of rows from the db. But I guess the explicit LIMIT clause helps with query performance.

[kagkarlsson]

🎉 This issue has been resolved in v13.0.0 (Release Notes)