I use DTrace fairly often to look at the boundaries between whatever interpreted language my app's written in and the kernel.
For example, at $job recently found that some of our Python code was doing 25k open64 calls but only 5k close calls during a scheduled job - this led us to find/fix a bug that would have been a disaster later.
For example, at $job recently found that some of our Python code was doing 25k open64 calls but only 5k close calls during a scheduled job - this led us to find/fix a bug that would have been a disaster later.