[crac] RFR: CRaC: Fix fds opened for logging

[Radim Vansa]

On Tue, 19 Sep 2023 14:30:15 GMT, Jan Kratochvil <jkratochvil at openjdk.org> wrote:

> CRaC: Fix fds opened for logging

A fix for a bug should be generally accompanied with a test.

I have doubts about the fix being in `is_fd_ignored`: while the function name is confusingly generic, it is used for exclusion of file descriptors inherited from parent process. The check for currently open FDs lives in `VM_Crac::check_fds`.

I think that a preferable solution would be to close those file descriptors used in logging (and reopen after restore), rather than keep them open and leave handling to CR engine. In my opinion close/reopen seems more aligned with the philosophy of coordinated checkpoint.

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PR Comment: https://git.openjdk.org/crac/pull/113#issuecomment-1725781903