How to Configure Parallel Execution in TestNG vs. Custom Excel Allocator

Optimizing test execution speed is essential for keeping build pipelines lean. Depending on how your framework is structured, you can achieve full parallel execution either natively using TestNG ** or dynamically using a **Custom Excel Allocator . Here is a step-by-step guide on configuring both approaches, along with a comparison to help you choose the right strategy. Strategy 1: Native TestNG Parallelization (Recommended for Code-Native Suites) TestNG natively supports parallel execution at the methods, classes, tests, or instances level using its XML configuration or Maven parameters. 1. Update testng_regression.xml Modify the tag to set the execution mode and thread pool size: <suite name= "Regression" parallel= "methods" thread-count= "10" > 2. Configure pom.xml for Dynamic Overrides Allow developers and CI pipelines to override execution settings without altering XML files by adding these lines inside the block of the maven-surefire-plugin: <parallel> ${parallel} </parallel> <threadCount> ${threadCount} </threadCount> 3. Execution Commands Default Run: mvn clean test -P runTestNGTests Override Thread Count Dynamically: mvn clean test -P runTestNGTests -DthreadCount = 15 Full Parallel Execution (Match CPU Core Count): mvn clean test -P runTestNGTests -Dparallel = methods -DthreadCount = 24 Strategy 2: Custom Allocator & Run Manager (For Excel-Driven Suites) If your framework relies on an Excel-driven Run Manager to parse keyword flows and data sheets dynamically, parallelism is managed via a custom ExecutorService fixed thread pool. Execution Command mvn clean test -P runAllocator How it works: The allocator reads active test rows (Execute=Yes), dynamically assigns thread pools based on target thread properties, and dispatches concurrent runs. Comparison: Allocator (Run Manager) vs. Native TestNG Feature Allocator (Run Manager) TestNG Native Entry Point allocator.Allocator.main() via Maven Exec Plugin maven-surefire-plugin executing testng.xml Test Selection Re