Process hierarchy incorrect on Linux about sysinfo HOT 7 CLOSED

Hum, seems weird but I'll check this evening. Thanks!

from sysinfo.

get_process_list() can be easier and more efficient by changing Process::task from HashMap<pid_t, Process> to Vec<pid_t>.

Also the field Process::pid is duplication, the value is already in the HashMap key.

from sysinfo.

A duplication of 4 bytes, so not a big deal. Also, it's way more efficient to search into a HashMap than into a Vec.

from sysinfo.

Also, in your current code, you're not really checking process hierarchy. The tasks are threads, not processes. In addition, in the first step you put None but all the processes ahve at least the process 1 as parent. Try with the following code:

fn check() {
    fn check_process_hierarchy(parent: Option<pid_t>, processes: &HashMap<pid_t,Process>) {
        for (pid, process) in processes {
            assert_eq!(process.pid, *pid);
            if !parent.is_none() {
                assert_eq!(process.parent, parent);
            }
            check_process_hierarchy(Some(*pid), &process.tasks);
        }
    }

    let mut sysinfo = System::new();
    sysinfo.refresh_processes();
    check_process_hierarchy(None, sysinfo.get_process_list());
}

from sysinfo.

it's way more efficient to search into a HashMap than into a Vec.

Yes, so if you want to know the parent of a process, you look up the process in the HashMap of all processes and tasks and get the parent property. If you want to know properties of the tasks, you take their pids from the tasks vector.

all the processes ahve at least the process 1 as parent.

Process 1 (init system, e.g. systemd) and 2 (kthreadd) have no parent. So Option<pid_t> for parent is fine. All other processes and threads have parents.

I expected that list_process would give me only the top processes (1 and 2), but now I understand that it's all processes and that tasks are threads. The fact that tasks have type Process is confusing.

from sysinfo.

The adapted check passes.

from sysinfo.

It's a trick, but since tasks are just like processes, I used the same struct. I should maybe state it more strongly in the docs...

from sysinfo.