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/exp5.go

@@ -0,0 +1,55 @@
+//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 0 }
+	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 0
+}
+func threads(pid int) int {
+	e, _ := os.ReadDir(fmt.Sprintf("/proc/%d/task", pid)); return len(e)
+}
+
+func main() {
+	fmt.Println("=== 实验 5：17 个 Go 子进程插件的真实常驻开销（PSS 计入共享页去重）===")
+	var cmds []*exec.Cmd
+	for i := 0; i < 17; i++ {
+		c := exec.Command("./plugbin")
+		c.Stdin, _ = os.Open(os.DevNull)
+		if err := c.Start(); err != nil { fmt.Println("start:", err); return }
+		cmds = append(cmds, c)
+	}
+	time.Sleep(1500 * time.Millisecond)
+
+	totalPss, totalThreads := 0, 0
+	for _, c := range cmds {
+		totalPss += pssKB(c.Process.Pid)
+		totalThreads += threads(c.Process.Pid)
+	}
+	fmt.Printf("17 进程合计: PSS = %.1f MB, 线程 = %d\n", float64(totalPss)/1024, totalThreads)
+	fmt.Printf("单进程均摊: PSS = %.2f MB, 线程 = %.1f\n",
+		float64(totalPss)/1024/17, float64(totalThreads)/17)
+	fmt.Printf("\n对照 homed 当前（单进程装 17 个 .so）:\n")
+	// 找 homed
+	out, _ := exec.Command("pgrep", "-x", "homed").Output()
+	if p := strings.TrimSpace(string(out)); p != "" {
+		pid, _ := strconv.Atoi(strings.Fields(p)[0])
+		fmt.Printf("  homed PSS = %.1f MB, 线程 = %d\n", float64(pssKB(pid))/1024, threads(pid))
+	}
+	for _, c := range cmds { c.Process.Kill(); c.Wait() }
+}