A native image is an operating system-specific executable file. You can build such an image for basically every application running on a Java virtual machine. This approach promises faster start-up times and lower resource consumption. This makes it appealing for serverless computing, auto-scaling platforms and command-line tools.<\/p>\n\n\n\n
I gained some impressions of this GraalVM technology while developing a standalone command line tool for formatting PL\/SQL and SQL code. In this blog post, I share some personal experiences and thoughts.<\/p>\n\n\n\n
My starting point is an executable JAR.\u00a0 I can run it from the command line via It’s quite obvious that this Java application loads a lot of classes and resources dynamically. The GraalVM’s native image builder can identify such objects with the tracing agent<\/a>. Using the agent is simple. You start the Java application with an additional parameter. The idea is to run the application long enough to detect all dynamically loaded classes and resources. Technically, the trace agent intercepts the calls involved in that dynamic loading process. It’s a best-effort approach. It cannot guarantee completeness.<\/p>\n\n\n\n The next command shows how I run the formatter with the tracing agent for a small PL\/SQL project:<\/p>\n\n\n\njava -jar tvdformat.jar<\/code>. The main class com.trivadis.plsql.formatter.TvdFormat<\/code> calls a JavaScript format.js<\/code> and passes all command line parameters to the JavaScript. Behind the scenes, Oracle’s parser and formatter which are part of SQLcl and SQL Developer do the heavy lifting.<\/p>\n\n\n\n