fixup: use sub-process pid check

Author: not-matthias

src/executor/shared/fifo.rs

@@ -241,6 +241,7 @@ impl RunnerFifo {
 
             let is_alive = health_check().await?;
             if !is_alive {
+                info!("Process terminated, stopping the command handler");
                 break;
             }
         }

src/executor/wall_time/perf/mod.rs

@@ -254,18 +254,27 @@ impl PerfRunner {
         let mut symbols_by_pid = HashMap::<pid_t, ProcessSymbols>::new();
         let mut unwind_data_by_pid = HashMap::<pid_t, Vec<UnwindData>>::new();
 
+        // The runner spawns a `bash` process, which will execute perf and the benchmark. To check if it
+        // terminated, we have to check if all the sub-processes terminated.
+        // We can't check for the `bash` process, because it will terminate after the FIFO handler has
+        // finished (because we're using a single-threaded runtime).
+        let mut sys = sysinfo::System::new();
         let health_check = async || {
-            let res = unsafe { libc::kill(pid, 0) };
-            if res == 0 {
-                return Ok(true);
-            }
+            sys.refresh_processes(sysinfo::ProcessesToUpdate::All, true);
+            let process = sys.process(sysinfo::Pid::from_u32(pid as u32));
+
+            match process {
+                None => Ok(false),
+                Some(_proc) => {
+                    let has_children = sys.processes().values().any(|p| {
+                        p.parent()
+                            .map(|parent_pid| parent_pid.as_u32() == pid as u32)
+                            .unwrap_or(false)
+                    });
 
-            let err = std::io::Error::last_os_error();
-            if err.raw_os_error() == Some(libc::ESRCH) {
-                return Ok(false);
+                    Ok(has_children)
+                }
             }
-
-            Ok(true)
         };
 
         let on_cmd = async |cmd: &FifoCommand| {