manpage for close is clear on its multithread use for a given file descriptor. However it's not stated really clear in case of duplicated file descriptors.

If i have a file descriptor duplicated (both point to the same resource), is that thread safe to perform close of each respective fd in different threads? There is a refcount used to release a resource at the last close, but is that access thread safe?

manpage for close is clear on its multithread use for a given file descriptor. However it's not stated really clear in case of duplicated file descriptors.

If i have a file descriptor duplicated (both point to the same resource), is that thread safe to perform close of each respective fd in different threads? There is a refcount used to release a resource at the last close, but is that access thread safe?

• c
• linux
• posix

• 1 As it says in the manpage, behavior varies across operating systems for ongoing file operations (such as write) using the same file descriptor in the same process at the time the file descriptor is being closed by the process, but other than that, you do not need to worry about it. – Ian Abbott Commented Feb 3 at 10:43

1 Answer 1

if i have a file descriptor duplicated (both point to the same resource), is that thread safe to perform close of each respective fd in different threads?

yes

There is a refcount used to release a resource at the last close, but is that access thread safe?

yes