try a different memory tracking approach

proto_package.go

@@ -220,7 +220,7 @@ func (p *ProtoPackage) build(ctx context.Context) (time.Duration, error) {
 		log.Errorf("error getting PGID: %v", err)
 	}
 
-	var peakMem int
+	var peakMem int64
 	done := make(chan bool)
 	go pollMemoryUsage(pgid, 1*time.Second, done, &peakMem)
 

utils.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"bufio"
 	"context"
 	"errors"
 	"fmt"
@@ -768,111 +767,123 @@ func downloadSRCINFO(pkg, tag string) (*srcinfo.Srcinfo, error) {
 	return nSrcInfo, nil
 }
 
-// getProcessMemory reads both RSS and Swap memory from /proc/<pid>/status
-func getProcessMemory(pid int) (int, int, error) {
-	statusPath := fmt.Sprintf("/proc/%d/status", pid)
-	file, err := os.Open(statusPath)
-	if err != nil {
-		return 0, 0, err
-	}
-	defer func(file *os.File) {
-		_ = file.Close()
-	}(file)
+func getDescendantPIDs(rootPID int) ([]int, error) {
+	pidToPpid := map[int]int{}
+	var descendants []int
 
-	var rss, swap int
-	scanner := bufio.NewScanner(file)
-	for scanner.Scan() {
-		line := scanner.Text()
-		fields := strings.Fields(line)
-		if len(fields) < 2 {
-			continue
-		}
-
-		switch fields[0] {
-		case "VmRSS:":
-			rss, err = strconv.Atoi(fields[1])
-			if err != nil {
-				return 0, 0, fmt.Errorf("failed to parse rss: %v", err)
-			}
-		case "VmSwap:":
-			swap, err = strconv.Atoi(fields[1])
-			if err != nil {
-				return 0, 0, fmt.Errorf("failed to parse swap: %v", err)
-			}
-		}
-	}
-	return rss, swap, nil
-}
-
-func getChildProcesses(pid int) ([]int, error) {
-	var children []int
-	taskPath := fmt.Sprintf("/proc/%d/task", pid)
-
-	taskDirs, err := os.ReadDir(taskPath)
+	procEntries, err := os.ReadDir("/proc")
 	if err != nil {
 		return nil, err
 	}
 
-	for _, task := range taskDirs {
-		childFile := fmt.Sprintf("/proc/%d/task/%s/children", pid, task.Name())
-		file, err := os.Open(childFile)
+	for _, entry := range procEntries {
+		if !entry.IsDir() || entry.Name()[0] < '0' || entry.Name()[0] > '9' {
+			continue
+		}
+		pidStr := entry.Name()
+		pid, err := strconv.Atoi(pidStr)
 		if err != nil {
 			continue
 		}
 
-		scanner := bufio.NewScanner(file)
-		for scanner.Scan() {
-			childPIDs := strings.Fields(scanner.Text())
-			for _, childStr := range childPIDs {
-				childPID, err := strconv.Atoi(childStr)
-				if err == nil {
-					children = append(children, childPID)
-					subChildren, _ := getChildProcesses(childPID)
-					children = append(children, subChildren...)
+		statusPath := filepath.Join("/proc", pidStr, "status")
+		data, err := os.ReadFile(statusPath)
+		if err != nil {
+			continue
+		}
+
+		for _, line := range strings.Split(string(data), "\n") {
+			if strings.HasPrefix(line, "PPid:") {
+				fields := strings.Fields(line)
+				if len(fields) == 2 {
+					ppid, _ := strconv.Atoi(fields[1])
+					pidToPpid[pid] = ppid
 				}
 			}
 		}
-		_ = file.Close()
 	}
-	return children, nil
+
+	var walk func(int)
+	walk = func(current int) {
+		for pid, ppid := range pidToPpid {
+			if ppid == current {
+				descendants = append(descendants, pid)
+				walk(pid)
+			}
+		}
+	}
+	walk(rootPID)
+	return descendants, nil
 }
 
-func getProcessTreeMemory(rootPID int) (int, int, error) {
-	pids := []int{rootPID}
+type MemStats struct {
+	RSS  int64
+	Swap int64
+}
 
-	childPIDs, err := getChildProcesses(rootPID)
-	if err == nil {
-		pids = append(pids, childPIDs...)
+func getMemoryStats(pid int) (MemStats, error) {
+	statusPath := fmt.Sprintf("/proc/%d/status", pid)
+	data, err := os.ReadFile(statusPath)
+	if err != nil {
+		return MemStats{}, err
 	}
 
-	totalRSS, totalSwap := 0, 0
-	for _, pid := range pids {
-		rss, swap, err := getProcessMemory(pid)
-		if err == nil {
-			totalRSS += rss
-			totalSwap += swap
+	stats := MemStats{}
+	for _, line := range strings.Split(string(data), "\n") {
+		if strings.HasPrefix(line, "VmRSS:") {
+			fields := strings.Fields(line)
+			if len(fields) >= 2 {
+				kb, _ := strconv.ParseInt(fields[1], 10, 64)
+				stats.RSS = kb * 1024
+			}
+		}
+		if strings.HasPrefix(line, "VmSwap:") {
+			fields := strings.Fields(line)
+			if len(fields) >= 2 {
+				kb, _ := strconv.ParseInt(fields[1], 10, 64)
+				stats.Swap = kb * 1024
+			}
 		}
 	}
 
-	return totalRSS, totalSwap, nil
+	return stats, nil
 }
 
-func pollMemoryUsage(pgid int, interval time.Duration, done chan bool, peakMem *int) {
+func pollMemoryUsage(pid int, interval time.Duration, done chan bool, peakMem *int64) {
 	for {
 		select {
 		case <-done:
 			return
 		default:
-			rss, swap, err := getProcessTreeMemory(pgid)
-			if err == nil {
-				totalMemory := rss + swap
+			totalRSS := int64(0)
+			totalSwap := int64(0)
 
-				if totalMemory > *peakMem {
-					peakMem = &totalMemory
-				}
+			rootStats, err := getMemoryStats(pid)
+			if err == nil {
+				totalRSS += rootStats.RSS
+				totalSwap += rootStats.Swap
 			} else {
-				log.Warningf("failed to get process tree memory: %v", err)
+				log.Errorf("failed to get memory stats for root process: %v", err)
 			}
+
+			descendants, err := getDescendantPIDs(pid)
+			if err != nil {
+				log.Errorf("failed to get descendants: %v", err)
+			}
+
+			for _, dpid := range descendants {
+				stats, err := getMemoryStats(dpid)
+				if err == nil {
+					totalRSS += stats.RSS
+					totalSwap += stats.Swap
+				}
+			}
+
+			totalMemory := totalRSS + totalSwap
+			if totalMemory > *peakMem {
+				peakMem = &totalMemory
+			}
+
 			time.Sleep(interval)
 		}
 	}