TestNG vs. Custom Excel Allocator: Two Approaches to Parallel Test Execution

A technical guide published on DEV Community outlines two strategies for achieving parallel test execution in automated testing frameworks. The first approach uses TestNG's native parallelization, configured via XML and Maven parameters, allowing CI pipelines to override thread counts dynamically without modifying source files. The second strategy employs a Custom Excel Allocator that uses Java's ExecutorService fixed thread pool to dispatch concurrent test runs based on active rows parsed from Excel sheets. Native TestNG is recommended for lightweight, code-first suites, while the Excel Allocator suits data-driven frameworks requiring fine-grained control over test instances and multi-sheet scheduling. The guide includes a side-by-side comparison of both methods across entry points, thread management, and command execution to help teams select the right approach.