1. A method for profiling application code, the method comprising: inserting instrumentation within application code; linking the application code to a runtime app profile generator for gathering per thread samples; generating an executable user application from the application code; executing the executable user application; launching the runtime app profile generator in response to execution of the application code; registering with the runtime app profile generator, during execution of the executable user application, each of different threads of the executable user application as each of the different threads is initiated; periodically sampling each of the different threads, without kernel-level support, during execution of the executable user application to obtain periodic samples of each of the different threads; and generating hybrid profiling results using the periodic samples from each of the different threads of the executable user application and accumulated instrumented execution information.