In computer science, performance analysis is the gathering of a program's performance characteristics by measuring events happening in a computer system while running the program. The output is a stream of the recorded events (called trace), or some summary information of events recorded (a profile). Statistical profilers Profilers may operate by sampling or instrumenting. A sampling profiler probes the target program's program counter at regular intervals using operating system interrupts. Sampling profiles are typically less accurate and specific, but allow the target program to run at near full speed. An instrumenting profilers equips the target program with additional instructions to collect the required information. This may cause changes in the performance of the program, leading to inaccurate results and heisenbugs. Instrumenting can potentially be very specific but slows down the target program as more specific information is collected.