Linux – An efficient way to get the number of file handles opened by a process in Go?

I have a monitoring agent called scollector that uses more CPU on our load balancer. Perf says CPUs are mostly due to __d_lookup. One of the things I monitor is the number of open file handles – I do this with the following code:

    fds, e := ioutil. ReadDir("/proc/" + pid + "/fd")
    if e != nil {
        w.Remove(pid)
        continue
    }
    ...
    Add(md, "linux.proc.num_fds", len(fds), tags, metadata. Gauge, metadata. Files, descLinuxProcFd)

When I trace a process, I see that it calls lstat on every file in the /fd directory (which would be a lot for our event load balancer (at least 500,000 fds) – so I’m assuming this is the source of the process’s high dentry cache cpu usage.

Does anyone have any suggestions for a better way to do this?

ioutil. The problem with Readdir is that it executes file. Readdir, which indicates that it performs lstat on each file.

It seems that Readdirnames does not do this, only returns the name. Since you only need to count, that’s enough.