docs(plugin-arch): 归档插件架构迁移评估 + plan 第11节整改计划

- docs/zh/架构迁移评估.md: C ABI→子进程+共享内存完整迁移论证(1621行)
- docs/zh/experiments/: 18项可复跑可行性实验(架构评估的所有数字来源)
- plan.md §11: 11.1~11.9 插件架构缺陷修复清单(唯一权威编号)
- main 保持干净,本批次为 update 特性分支的整改起点

docs/zh/experiments/plugin-arch/02-feasibility/exp5b.go

@@ -0,0 +1,68 @@
+//go:build ignore
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+	"time"
+)
+
+func pssKB(pid int) int {
+	b, err := os.ReadFile(fmt.Sprintf("/proc/%d/smaps_rollup", pid))
+	if err != nil { return -1 }
+	for _, l := range strings.Split(string(b), "\n") {
+		if strings.HasPrefix(l, "Pss:") { f := strings.Fields(l); n,_ := strconv.Atoi(f[1]); return n }
+	}
+	return -1
+}
+func rssKB(pid int) int {
+	b, err := os.ReadFile(fmt.Sprintf("/proc/%d/status", pid))
+	if err != nil { return -1 }
+	for _, l := range strings.Split(string(b), "\n") {
+		if strings.HasPrefix(l, "VmRSS:") { f := strings.Fields(l); n,_ := strconv.Atoi(f[1]); return n }
+	}
+	return -1
+}
+func threads(pid int) int { e,_ := os.ReadDir(fmt.Sprintf("/proc/%d/task", pid)); return len(e) }
+
+func main() {
+	fmt.Println("=== 实验 5b：17 个 Go 子进程常驻开销（保持 stdin 管道存活）===")
+	var cmds []*exec.Cmd
+	var pipes []interface{ Close() error }
+	for i := 0; i < 17; i++ {
+		c := exec.Command("./plugbin")
+		w, _ := c.StdinPipe()   // 保持打开 → 不 EOF
+		pipes = append(pipes, w)
+		c.Stdout = nil
+		if err := c.Start(); err != nil { fmt.Println(err); return }
+		cmds = append(cmds, c)
+	}
+	time.Sleep(2 * time.Second)
+
+	tp, tr, tt, alive := 0, 0, 0, 0
+	for _, c := range cmds {
+		pid := c.Process.Pid
+		if _, err := os.Stat(fmt.Sprintf("/proc/%d", pid)); err != nil { continue }
+		alive++
+		if v := pssKB(pid); v > 0 { tp += v }
+		if v := rssKB(pid); v > 0 { tr += v }
+		tt += threads(pid)
+	}
+	fmt.Printf("存活进程 %d/17\n", alive)
+	fmt.Printf("合计: PSS=%.1f MB  RSS=%.1f MB  线程=%d\n",
+		float64(tp)/1024, float64(tr)/1024, tt)
+	if alive > 0 {
+		fmt.Printf("均摊: PSS=%.2f MB  RSS=%.2f MB  线程=%.1f\n",
+			float64(tp)/1024/float64(alive), float64(tr)/1024/float64(alive), float64(tt)/float64(alive))
+	}
+	out, _ := exec.Command("pgrep", "-x", "homed").Output()
+	if p := strings.TrimSpace(string(out)); p != "" {
+		pid, _ := strconv.Atoi(strings.Fields(p)[0])
+		fmt.Printf("\n对照 homed（单进程 + 17 个 .so）: RSS=%.1f MB 线程=%d\n",
+			float64(rssKB(pid))/1024, threads(pid))
+	}
+	for _, c := range cmds { c.Process.Kill(); c.Wait() }
+}