fix: reap leaders during group shutdown

stelloauth/rootfs/usr/local/bin/addon-supervisor

@@ -211,6 +211,7 @@ class ProcessManager:
         self._sleep = sleep
         self._profile_path = profile_path
         self._children: list[tuple[str, subprocess.Popen]] = []
+        self._reaped_children: set[int] = set()
         self._groups: list[int] = []
         self._dead_groups: set[int] = set()
         self._stopping = False
@@ -255,7 +256,19 @@ class ProcessManager:
     def _startup_stopping(self) -> bool:
         return self._stopping or self._first_exited_child() is not None
 
+    def _reap_exited_children(self) -> None:
+        for _name, process in self._children:
+            if process.pid in self._reaped_children or process.poll() is None:
+                continue
+            try:
+                process.wait(timeout=None)
+            except OSError:
+                logging.error("Child process reap failed")
+            else:
+                self._reaped_children.add(process.pid)
+
     def _live_groups(self) -> list[int]:
+        self._reap_exited_children()
         live_groups = []
         for pgid in self._groups:
             if pgid in self._dead_groups:
@@ -291,10 +304,14 @@ class ProcessManager:
 
     def _reap_all(self) -> None:
         for _name, process in self._children:
+            if process.pid in self._reaped_children:
+                continue
             try:
                 process.wait(timeout=None)
             except OSError:
                 logging.error("Child process reap failed")
+            else:
+                self._reaped_children.add(process.pid)
 
     def _shutdown(self) -> None:
         if not self._children: