Fix LinuxEvents destructor to close all fd

[Jens-H]

Here would be how I solved running out of fds.

[lemire]

Thanks for the PR. Can you explain this code?

[Jens-H]

Certainly. It takes the last opened file descriptor (fd) assigned in the for-loop lines 41-51. Then it closes this fd and the next x-1 smaller fd, where x is the number of perf events (stored in num_events) for the LinuxEvents instance. Obviously this is a hack, as the really opened fd are not used, but guessed.

[thomasmueller]

What about keeping the list of file descriptors in a std::vector?

[Jens-H]

What about keeping the list of file descriptors in a std::vector?

Most probably a cleaner and more general solution.

I should add that I am not sure how the start/end method is working with just the last fd. This is why I decided to just do a fix in the destructor and leave everything else as it is.