Profile and monitor in real time
The heap profile report file <program>.hp is generated as the program executes, so it's perfectly fine to take a snapshot of the file at any time and visualize it with hp2ps, even if the program is still busy executing. Because very basic heap profiling (-hT) is possible without having compiled with profiling support, it is possible to produce running heap profiles with a very small overhead.
Increasing the sample interval -i to something relatively big, such as a couple of seconds, it is very feasible to extract heap profiles from long-running programs even in production environments.
A quick-and-dirty trick that isn't for the light-hearted is the -S Runtime System option. This option prints garbage collector statistics ...
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