An analysis and visualization depicts how an application is leveraging processor cores of a distributed computing system, such as a computer cluster, in time. The analysis and visualization enables a developer to readily identify the degree of concurrency exploited by an application at runtime and the amount of overhead used by libraries or middleware. Information regarding processes or threads running on the nodes over time is received, analyzed, and presented to indicate portions of computer cluster that are used by the application, idle, other processes, and libraries in the system. The analysis and visualization can help a developer understand or confirm contention for or under-utilization of system resources for the application and libraries.