Function update_pid1_stats 

pub async fn update_pid1_stats(
    pid: i32,
    locked_machine_stats: Arc<RwLock<MachineStats>>,
) -> Result<()>

Async wrapper than can update PID1 stats when passed a locked struct

Split into two spans (blocking procfs read vs. write-lock acquisition) so a slow run can be attributed to actual work vs. contention on the MachineStats lock shared with every other collector.