Reduce agent RSS

cmd/agent/main.go

@@ -16,6 +16,8 @@ import (
 
 	"github.com/DataDog/datadog-agent/cmd/agent/command"
 	"github.com/DataDog/datadog-agent/cmd/agent/subcommands"
+
+	"github.com/DataDog/datadog-agent/cmd/internal/rssshrinker"
 	"github.com/DataDog/datadog-agent/cmd/internal/runcmd"
 	"github.com/spf13/cobra"
 )
@@ -37,6 +39,10 @@ func init() {
 }
 
 func main() {
+	if err := rssshrinker.ReleaseMemory(); err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to release memory: %s\n", err)
+	}
+
 	process := strings.TrimSpace(os.Getenv("DD_BUNDLED_AGENT"))
 
 	if process == "" {

cmd/internal/rssshrinker/rssshrinker_linux.go

@@ -0,0 +1,76 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2024-present Datadog, Inc.
+
+//go:build linux
+
+// Package rssshrinker provides functions to reduce the process’ RSS
+package rssshrinker
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+	"syscall"
+	"unsafe"
+)
+
+//revive:disable:var-naming
+
+// MADV_PAGEOUT Reclaim these pages.
+const MADV_PAGEOUT = 21
+
+//revive:enable:var-naming
+
+// ReleaseMemory releases memory by calling madvise with MADV_PAGEOUT on all
+func ReleaseMemory() error {
+	selfMap, err := os.Open("/proc/self/maps")
+	if err != nil {
+		return fmt.Errorf("failed to open /proc/self/maps: %w", err)
+	}
+	defer selfMap.Close()
+
+	scanner := bufio.NewScanner(selfMap)
+	for scanner.Scan() {
+		fields := strings.Fields(scanner.Text())
+
+		if len(fields) != 6 {
+			continue
+		}
+
+		address, perms, _ /* offset */, _ /* device */, _ /* inode */, pathname := fields[0], fields[1], fields[2], fields[3], fields[4], fields[5]
+
+		if strings.HasPrefix(pathname, "[") {
+			continue
+		}
+
+		if len(perms) != 4 || perms[0] != 'r' || perms[1] != '-' {
+			continue
+		}
+
+		beginStr, endStr, found := strings.Cut(address, "-")
+		if !found {
+			continue
+		}
+
+		begin, err := strconv.ParseUint(beginStr, 16, 64)
+		if err != nil {
+			return fmt.Errorf("failed to parse begin address %q: %w", beginStr, err)
+		}
+
+		end, err := strconv.ParseUint(endStr, 16, 64)
+		if err != nil {
+			return fmt.Errorf("failed to parse end address %q: %w", endStr, err)
+		}
+
+		// nolint:govet:unsafeptr
+		if err := syscall.Madvise(unsafe.Slice((*byte)(unsafe.Pointer(uintptr(begin))), end-begin), MADV_PAGEOUT); err != nil {
+			return fmt.Errorf("failed to madvise: %w", err)
+		}
+	}
+
+	return nil
+}

cmd/internal/rssshrinker/rssshrinker_stub.go

@@ -0,0 +1,14 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2024-present Datadog, Inc.
+
+//go:build !linux
+
+// Package rssshrinker provides functions to reduce the process’ RSS
+package rssshrinker
+
+// ReleaseMemory isn’t implemented on this platform
+func ReleaseMemory() error {
+	return nil
+}

cmd/process-agent/main.go

@@ -7,9 +7,11 @@
 package main
 
 import (
+	"fmt"
 	_ "net/http/pprof"
 	"os"
 
+	"github.com/DataDog/datadog-agent/cmd/internal/rssshrinker"
 	"github.com/DataDog/datadog-agent/cmd/internal/runcmd"
 	"github.com/DataDog/datadog-agent/cmd/process-agent/command"
 	"github.com/DataDog/datadog-agent/cmd/process-agent/subcommands"
@@ -18,6 +20,10 @@ import (
 
 // main is the main application entry point
 func main() {
+	if err := rssshrinker.ReleaseMemory(); err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to release memory: %s\n", err)
+	}
+
 	flavor.SetFlavor(flavor.ProcessAgent)
 
 	os.Args = command.FixDeprecatedFlags(os.Args, os.Stdout)

cmd/security-agent/main_nix.go

@@ -9,18 +9,24 @@
 package main
 
 import (
+	"fmt"
 	"os"
 
 	_ "expvar"         // Blank import used because this isn't directly used in this file
 	_ "net/http/pprof" // Blank import used because this isn't directly used in this file
 
+	"github.com/DataDog/datadog-agent/cmd/internal/rssshrinker"
 	"github.com/DataDog/datadog-agent/cmd/internal/runcmd"
 	"github.com/DataDog/datadog-agent/cmd/security-agent/command"
 	"github.com/DataDog/datadog-agent/cmd/security-agent/subcommands"
 	"github.com/DataDog/datadog-agent/pkg/util/flavor"
 )
 
 func main() {
+	if err := rssshrinker.ReleaseMemory(); err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to release memory: %s\n", err)
+	}
+
 	// set the Agent flavor
 	flavor.SetFlavor(flavor.SecurityAgent)
 

cmd/system-probe/main.go

@@ -9,14 +9,20 @@
 package main
 
 import (
+	"fmt"
 	"os"
 
+	"github.com/DataDog/datadog-agent/cmd/internal/rssshrinker"
 	"github.com/DataDog/datadog-agent/cmd/internal/runcmd"
 	"github.com/DataDog/datadog-agent/cmd/system-probe/command"
 	"github.com/DataDog/datadog-agent/cmd/system-probe/subcommands"
 )
 
 func main() {
+	if err := rssshrinker.ReleaseMemory(); err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to release memory: %s\n", err)
+	}
+
 	rootCmd := command.MakeCommand(subcommands.SysprobeSubcommands())
 	command.SetDefaultCommandIfNonePresent(rootCmd)
 	os.Exit(runcmd.Run(rootCmd))

cmd/trace-agent/main.go

@@ -7,14 +7,20 @@
 package main
 
 import (
+	"fmt"
 	"os"
 
+	"github.com/DataDog/datadog-agent/cmd/internal/rssshrinker"
 	"github.com/DataDog/datadog-agent/cmd/internal/runcmd"
 	"github.com/DataDog/datadog-agent/cmd/trace-agent/command"
 	"github.com/DataDog/datadog-agent/pkg/util/flavor"
 )
 
 func main() {
+	if err := rssshrinker.ReleaseMemory(); err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to release memory: %s\n", err)
+	}
+
 	flavor.SetFlavor(flavor.TraceAgent)
 
 	os.Args = command.FixDeprecatedFlags(os.Args, os.Stdout)