From 62acd578e0f0793dc156346ce43b549f803904ed Mon Sep 17 00:00:00 2001
From: toller892 <toller892@users.noreply.github.com>
Date: Tue, 2 Jun 2026 08:30:59 +0800
Subject: [PATCH] fix: reap zombie child processes in container environments

When soft-serve runs as PID 1 in a container without an init supervisor,
orphaned descendant processes (e.g. git pack-objects left behind when a
git parent exits) are reparented to PID 1 and become zombies because the
Go runtime only tracks children spawned via os/exec.

Add a periodic reaper goroutine that calls waitpid(-1, WNOHANG) every
10 seconds to clean up any zombie children. The reaper runs only on
Linux (where the PID 1 container issue manifests) and is a no-op on
other platforms.

Fixes #891
---
 cmd/soft/serve/reap_linux.go | 42 ++++++++++++++++++++++++++++++++++++
 cmd/soft/serve/reap_other.go | 13 +++++++++++
 cmd/soft/serve/serve.go      |  5 +++++
 3 files changed, 60 insertions(+)
 create mode 100644 cmd/soft/serve/reap_linux.go
 create mode 100644 cmd/soft/serve/reap_other.go

diff --git a/cmd/soft/serve/reap_linux.go b/cmd/soft/serve/reap_linux.go
new file mode 100644
index 000000000..f3f9a3a28
--- /dev/null
+++ b/cmd/soft/serve/reap_linux.go
@@ -0,0 +1,42 @@
+//go:build linux
+
+package serve
+
+import (
+	"context"
+	"time"
+
+	"charm.land/log/v2"
+	"golang.org/x/sys/unix"
+)
+
+// reapZombies periodically reaps zombie child processes.
+//
+// When soft-serve runs as PID 1 in a container, orphaned descendant
+// processes (e.g. grandchild git pack-objects left behind when a git
+// parent exits before waiting for them) are reparented to PID 1.
+// Without an init system these processes become zombies because the
+// Go runtime only tracks children spawned via os/exec, not reparented
+// orphans. This goroutine periodically calls waitpid(-1, WNOHANG) to
+// clean them up.
+func reapZombies(ctx context.Context, logger *log.Logger) {
+	go func() {
+		ticker := time.NewTicker(10 * time.Second)
+		defer ticker.Stop()
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-ticker.C:
+				for {
+					var status unix.WaitStatus
+					pid, err := unix.Wait4(-1, &status, unix.WNOHANG, nil)
+					if err != nil || pid <= 0 {
+						break
+					}
+					logger.Debugf("reaped zombie child pid=%d status=%d", pid, status)
+				}
+			}
+		}
+	}()
+}
diff --git a/cmd/soft/serve/reap_other.go b/cmd/soft/serve/reap_other.go
new file mode 100644
index 000000000..4a9aeca13
--- /dev/null
+++ b/cmd/soft/serve/reap_other.go
@@ -0,0 +1,13 @@
+//go:build !linux
+
+package serve
+
+import (
+	"context"
+
+	"charm.land/log/v2"
+)
+
+// reapZombies is a no-op on non-Linux platforms.
+// See reap_linux.go for the Linux implementation.
+func reapZombies(_ context.Context, _ *log.Logger) {}
diff --git a/cmd/soft/serve/serve.go b/cmd/soft/serve/serve.go
index 7472f3d0b..d91b74bd1 100644
--- a/cmd/soft/serve/serve.go
+++ b/cmd/soft/serve/serve.go
@@ -75,6 +75,11 @@ var (
 				return fmt.Errorf("start server: %w", err)
 			}
 
+			// Start zombie child reaper for container environments where
+			// soft-serve may run as PID 1 without an init supervisor.
+			// See https://github.com/charmbracelet/soft-serve/issues/891
+			reapZombies(ctx, s.logger)
+
 			if syncHooks {
 				be := backend.FromContext(ctx)
 				if err := cmd.InitializeHooks(ctx, cfg, be); err != nil {