How Conditional Breakpoints Work

Conditional breakpoints are a powerful debugging tool, but their performance can be a concern. Debuggers like Visual Studio and raddbg face challenges in executing conditional breakpoints efficiently, with delays of around 2 seconds for simple loop iterations. The implementation typically involves saving the condition as a string and evaluating it each time the breakpoint is hit. This process can be slow, especially for complex expressions, impacting performance significantly. Modern debuggers, such as delve and raddbg, evaluate conditions using various approaches, like parsing expressions with a compiler like clang. To enhance performance, some debuggers are exploring injecting code to check conditions directly into the process, avoiding the need to stop and resume execution repeatedly. Leveraging in-process agents or JIT compilation can lead to substantial performance improvements, as seen with the UDB debugger achieving a ~1000x speedup. While the idea of using JIT for conditional breakpoints is promising, there are still challenges in its full implementation.