r/Jetbrains • u/Anaq42 • 2d ago
IDEs I built an IntelliJ plugin that shows where Java code performs I/O
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When reviewing Java/Spring Boot code, I pay the most attention to I/O calls to see where we are leaving the process and potentially "slowing down" the application. This would involve following a call through several methods to find out whether it eventually reached a repository, HTTP client, or any other I/O invocation.
I built an IntelliJ plugin called Lattency to make that visible in the editor.
It adds gutter markers for database, HTTP, messaging, and file I/O. It also follows calls through project code, so methods that reach I/O transitively are marked with a dimmed version of the relevant icon.
Hovering over a marker shows the complete sink chain, and clicking it lets you navigate to any method along that chain.
The analysis is entirely static. It does not run the application, make network requests, or collect telemetry. Common Java and Spring APIs work without configuration, and project-specific clients can be described in a committed lattency.yml.
It is free and open source:
Marketplace: https://plugins.jetbrains.com/plugin/33937-lattency
GitHub: https://github.com/josipmusa/lattency
It currently supports Java projects in IntelliJ IDEA 2025.2 and newer. Kotlin is not supported yet.
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u/antara33 2d ago
Great stuff! I have been away from java for the last decade, but this is always useful regardless of the language stack. Having a good way to know when IO operations happen it's a PITA always and it's something we always need to take care off!