chore(redactors): memory consumption improvements (#1332)

* Document additional go tool profiling flags

* Add a regex cache to avoid compiling regular expressions all the time

* Reduce max buffer capacity

* Prefer bytes to strings

Strings are immutable and hence we need to create a new one
all the time when operation on them

* Some more changes

* More bytes

* Use writer.Write instead of fmt.FPrintf

* Clear regex cache when resetting redactors

* Logs errors when redactors error since they get swallowed

* Add an improvement comment

* Limit the number of goroutines spawned when redacting

* Minor improvement

* Write byte slices one at a time instead of concatenating them first

* Add a test for writeBytes

* Additional tests

CONTRIBUTING.md

@@ -94,6 +94,12 @@ go tool pprof -http=":8000" cpu.prof
 go tool pprof -http=":8001" mem.prof
 ```
 
+**Additional flags for memory profiling**
+- `inuse_space`: Amount of memory allocated and not released yet (default).
+- `inuse_objects`: Amount of objects allocated and not released yet.
+- `alloc_space`: Total amount of memory allocated (regardless of released).
+- `alloc_objects`: Total amount of objects allocated (regardless of released).
+
 More on profiling please visit https://go.dev/doc/diagnostics#profiling
 
 ## Contribution workflow

pkg/collect/redact.go

@@ -5,7 +5,6 @@ import (
 	"bytes"
 	"compress/gzip"
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -17,18 +16,29 @@ import (
 	"k8s.io/klog/v2"
 )
 
+// Max number of concurrent redactors to run
+// Ensure the number is low enough since each of the redactors
+// also spawns goroutines to redact files in tar archives and
+// other goroutines for each redactor spec.
+const MAX_CONCURRENT_REDACTORS = 10
+
 func RedactResult(bundlePath string, input CollectorResult, additionalRedactors []*troubleshootv1beta2.Redact) error {
 	wg := &sync.WaitGroup{}
 
 	// Error channel to capture errors from goroutines
 	errorCh := make(chan error, len(input))
+	limitCh := make(chan struct{}, MAX_CONCURRENT_REDACTORS)
+	defer close(limitCh)
 
 	for k, v := range input {
+		limitCh <- struct{}{}
 
 		wg.Add(1)
 
 		go func(file string, data []byte) {
 			defer wg.Done()
+			defer func() { <-limitCh }() // free up after the function execution has run
+
 			var reader io.Reader
 			if data == nil {
 
@@ -84,7 +94,7 @@ func RedactResult(bundlePath string, input CollectorResult, additionalRedactors
 			// If the file is .tar, .tgz or .tar.gz, it must not be redacted. Instead it is
 			// decompressed and each file inside the tar redacted and compressed back into the archive.
 			if filepath.Ext(file) == ".tar" || filepath.Ext(file) == ".tgz" || strings.HasSuffix(file, ".tar.gz") {
-				tmpDir, err := ioutil.TempDir("", "troubleshoot-subresult-")
+				tmpDir, err := os.MkdirTemp("", "troubleshoot-subresult-")
 				if err != nil {
 					errorCh <- errors.Wrap(err, "failed to create temp dir")
 					return

pkg/collect/result.go

@@ -132,7 +132,7 @@ func (r CollectorResult) SaveResult(bundlePath string, relativePath string, read
 		return errors.Wrap(err, "failed to stat file")
 	}
 
-	klog.V(2).Infof("Added %q (%d MB) to bundle output", relativePath, fileInfo.Size()/(1024*1024))
+	klog.V(2).Infof("Added %q (%d KB) to bundle output", relativePath, fileInfo.Size()/(1024))
 	return nil
 }
 

pkg/constants/constants.go

@@ -83,6 +83,11 @@ const (
 	MESSAGE_TEXT_PADDING                = 4
 	MESSAGE_TEXT_LINES_MARGIN_TO_BOTTOM = 4
 
-	// Bufio Reader Constants
-	MAX_BUFFER_CAPACITY = 1024 * 1024
+	// This is the initial size of the buffer allocated.
+	// Under the hood, an array of size N is allocated in memory
+	BUF_INIT_SIZE = 4096 // 4KB
+
+	// This is the muximum size the buffer can grow to
+	// Its not what the buffer will be allocated to initially
+	SCANNER_MAX_SIZE = 10 * 1024 * 1024 // 10MB
 )

pkg/redact/literal.go

@@ -2,23 +2,26 @@ package redact
 
 import (
 	"bufio"
+	"bytes"
 	"fmt"
 	"io"
-	"strings"
+
+	"github.com/replicatedhq/troubleshoot/pkg/constants"
+	"k8s.io/klog/v2"
 )
 
 type literalRedactor struct {
-	matchString string
-	filePath    string
-	redactName  string
-	isDefault   bool
+	match      []byte
+	filePath   string
+	redactName string
+	isDefault  bool
 }
 
-func literalString(matchString, path, name string) Redactor {
+func literalString(match []byte, path, name string) Redactor {
 	return literalRedactor{
-		matchString: matchString,
-		filePath:    path,
-		redactName:  name,
+		match:      match,
+		filePath:   path,
+		redactName: name,
 	}
 }
 
@@ -28,32 +31,37 @@ func (r literalRedactor) Redact(input io.Reader, path string) io.Reader {
 	go func() {
 		var err error
 		defer func() {
-			if err == io.EOF {
+			if err == nil || err == io.EOF {
 				writer.Close()
 			} else {
+				if err == bufio.ErrTooLong {
+					s := fmt.Sprintf("Error redacting %q. A line in the file exceeded %d MB max length", path, constants.SCANNER_MAX_SIZE/1024/1024)
+					klog.V(2).Info(s)
+				} else {
+					klog.V(2).Info(fmt.Sprintf("Error redacting %q: %v", path, err))
+				}
 				writer.CloseWithError(err)
 			}
 		}()
 
-		reader := bufio.NewReader(input)
+		buf := make([]byte, constants.BUF_INIT_SIZE)
+		scanner := bufio.NewScanner(input)
+		scanner.Buffer(buf, constants.SCANNER_MAX_SIZE)
+
 		lineNum := 0
-		for {
+		for scanner.Scan() {
 			lineNum++
-			var line string
-			line, err = readLine(reader)
-			if err != nil {
-				return
-			}
+			line := scanner.Bytes()
 
-			clean := strings.ReplaceAll(line, r.matchString, MASK_TEXT)
+			clean := bytes.ReplaceAll(line, r.match, maskTextBytes)
 
-			// io.WriteString would be nicer, but scanner strips new lines
-			fmt.Fprintf(writer, "%s\n", clean)
+			// Append newline since scanner strips it
+			err = writeBytes(writer, clean, NEW_LINE)
 			if err != nil {
 				return
 			}
 
-			if clean != line {
+			if !bytes.Equal(clean, line) {
 				addRedaction(Redaction{
 					RedactorName:      r.redactName,
 					CharactersRemoved: len(line) - len(clean),
@@ -63,6 +71,9 @@ func (r literalRedactor) Redact(input io.Reader, path string) io.Reader {
 				})
 			}
 		}
+		if scanErr := scanner.Err(); scanErr != nil {
+			err = scanErr
+		}
 	}()
 	return out
 }

pkg/redact/multi_line.go

@@ -2,10 +2,9 @@ package redact
 
 import (
 	"bufio"
-	"fmt"
+	"bytes"
 	"io"
 	"regexp"
-	"strings"
 )
 
 type MultiLineRedactor struct {
@@ -20,19 +19,19 @@ type MultiLineRedactor struct {
 
 func NewMultiLineRedactor(re1 LineRedactor, re2 string, maskText, path, name string, isDefault bool) (*MultiLineRedactor, error) {
 	var scanCompiled *regexp.Regexp
-	compiled1, err := regexp.Compile(re1.regex)
+	compiled1, err := compileRegex(re1.regex)
 	if err != nil {
 		return nil, err
 	}
 
 	if re1.scan != "" {
-		scanCompiled, err = regexp.Compile(re1.scan)
+		scanCompiled, err = compileRegex(re1.scan)
 		if err != nil {
 			return nil, err
 		}
 	}
 
-	compiled2, err := regexp.Compile(re2)
+	compiled2, err := compileRegex(re2)
 	if err != nil {
 		return nil, err
 	}
@@ -48,14 +47,18 @@ func (r *MultiLineRedactor) Redact(input io.Reader, path string) io.Reader {
 			writer.CloseWithError(err)
 		}()
 
-		substStr := getReplacementPattern(r.re2, r.maskText)
+		substStr := []byte(getReplacementPattern(r.re2, r.maskText))
 
 		reader := bufio.NewReader(input)
 		line1, line2, err := getNextTwoLines(reader, nil)
 		if err != nil {
 			// this will print 2 blank lines for empty input...
-			fmt.Fprintf(writer, "%s\n", line1)
-			fmt.Fprintf(writer, "%s\n", line2)
+			// Append newlines since scanner strips them
+			err = writeBytes(writer, line1, NEW_LINE, line2, NEW_LINE)
+			if err != nil {
+				return
+			}
+
 			return
 		}
 
@@ -66,33 +69,41 @@ func (r *MultiLineRedactor) Redact(input io.Reader, path string) io.Reader {
 
 			// is scan is not nil, then check if line1 matches scan by lowercasing it
 			if r.scan != nil {
-				lowerLine1 := strings.ToLower(line1)
-				if !r.scan.MatchString(lowerLine1) {
-					fmt.Fprintf(writer, "%s\n", line1)
-					line1, line2, err = getNextTwoLines(reader, &line2)
+				lowerLine1 := bytes.ToLower(line1)
+				if !r.scan.Match(lowerLine1) {
+					// Append newline since scanner strips it
+					err = writeBytes(writer, line1, NEW_LINE)
+					if err != nil {
+						return
+					}
+					line1, line2, err = getNextTwoLines(reader, line2)
 					flushLastLine = true
 					continue
 				}
 			}
 
 			// If line1 matches re1, then transform line2 using re2
-			if !r.re1.MatchString(line1) {
-				fmt.Fprintf(writer, "%s\n", line1)
-				line1, line2, err = getNextTwoLines(reader, &line2)
+			if !r.re1.Match(line1) {
+				// Append newline since scanner strips it
+				err = writeBytes(writer, line1, NEW_LINE)
+				if err != nil {
+					return
+				}
+				line1, line2, err = getNextTwoLines(reader, line2)
 				flushLastLine = true
 				continue
 			}
 			flushLastLine = false
-			clean := r.re2.ReplaceAllString(line2, substStr)
+			clean := r.re2.ReplaceAll(line2, substStr)
 
-			// io.WriteString would be nicer, but reader strips new lines
-			fmt.Fprintf(writer, "%s\n%s\n", line1, clean)
+			// Append newlines since scanner strips them
+			err = writeBytes(writer, line1, NEW_LINE, clean, NEW_LINE)
 			if err != nil {
 				return
 			}
 
 			// if clean is not equal to line2, a redaction was performed
-			if clean != line2 {
+			if !bytes.Equal(clean, line2) {
 				addRedaction(Redaction{
 					RedactorName:      r.redactName,
 					CharactersRemoved: len(line2) - len(clean),
@@ -106,15 +117,18 @@ func (r *MultiLineRedactor) Redact(input io.Reader, path string) io.Reader {
 		}
 
 		if flushLastLine {
-			fmt.Fprintf(writer, "%s\n", line1)
+			// Append newline since scanner strip it
+			err = writeBytes(writer, line1, NEW_LINE)
+			if err != nil {
+				return
+			}
 		}
 	}()
 	return out
 }
 
-func getNextTwoLines(reader *bufio.Reader, curLine2 *string) (line1 string, line2 string, err error) {
-	line1 = ""
-	line2 = ""
+func getNextTwoLines(reader *bufio.Reader, curLine2 []byte) (line1 []byte, line2 []byte, err error) {
+	line2 = []byte{}
 
 	if curLine2 == nil {
 		line1, err = readLine(reader)
@@ -126,11 +140,23 @@ func getNextTwoLines(reader *bufio.Reader, curLine2 *string) (line1 string, line
 		return
 	}
 
-	line1 = *curLine2
+	line1 = curLine2
 	line2, err = readLine(reader)
 	if err != nil {
 		return
 	}
 
 	return
 }
+
+// writeBytes writes all byte slices to the writer
+// in the order they are passed in the variadic argument
+func writeBytes(w io.Writer, bs ...[]byte) error {
+	for _, b := range bs {
+		_, err := w.Write(b)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}