callgrindoutpid

Callgrindoutpid is a term used in the context of the Valgrind profiling tool Callgrind to refer to the per-process Callgrind output associated with a specific process identifier (PID). When profiling programs that start multiple processes or spawn child processes, Callgrind can generate separate data files for each process, enabling per-process analysis of call graphs and instruction counts.

The standard behavior of Callgrind is to produce an output file containing detailed profiling data. By default, the primary per-process file is named callgrind.out.[pid], where [pid] is the operating system process ID. This naming convention helps distinguish data from different processes in multi-process workloads. The data inside these files includes function call relationships, call counts, and instruction counts, suitable for subsequent viewing with specialized tools.

Users can customize output naming with the appropriate Valgrind option. For example, you can specify a custom filename for the Callgrind output, which may affect how per-process files are named or merged. When running with multiple processes or when tracing child processes, you may observe several callgrind.out.* files, each corresponding to a different process.

Tools commonly used to view and analyze callgrindoutpid data include callgrind_annotate and graphical viewers such as KCachegrind or QCachegrind. These tools render the call graphs and counters, facilitating performance optimization by highlighting hot paths and frequently called functions. Callgrindoutpid thus refers to the per-PID profiling data produced by Callgrind, enabling targeted analysis of individual processes within a multi-process application.