VictoriaMetrics/lib/protoparser/common/lines_reader.go
Roman Khavronenko 0cf55ded34
lib/protoparser: decrease import.maxLineLen from 100MB to 10MB (#5364)
Tests showed that importing a single line with 70MB size takes 5.3GiB
RSS memory for VictoriaMetrics single-node.
In the scenario when user exports and imports data from one VM to another,
it could possibly lead to OOM exception for destination VM.

Importing a single line with 16MB size taks 1.3GiB RSS memory.
Hence, the limit for `import.maxLineLen` was decreased from 100MB to 10MB
to improve reliability of VictoriaMetrics during imports.

Signed-off-by: hagen1778 <roman@victoriametrics.com>
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
2023-11-24 12:53:04 +02:00

101 lines
3 KiB
Go

package common
import (
"bytes"
"errors"
"fmt"
"io"
"strings"
"time"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
)
// The maximum size of a single line returned by ReadLinesBlock.
const maxLineSize = 256 * 1024
// Default size in bytes of a single block returned by ReadLinesBlock.
const defaultBlockSize = 64 * 1024
// ReadLinesBlock reads a block of lines delimited by '\n' from tailBuf and r into dstBuf.
//
// Trailing chars after the last newline are put into tailBuf.
//
// Returns (dstBuf, tailBuf).
//
// It is expected that read timeout on r exceeds 1 second.
func ReadLinesBlock(r io.Reader, dstBuf, tailBuf []byte) ([]byte, []byte, error) {
return ReadLinesBlockExt(r, dstBuf, tailBuf, maxLineSize)
}
// ReadLinesBlockExt reads a block of lines delimited by '\n' from tailBuf and r into dstBuf.
//
// Trailing chars after the last newline are put into tailBuf.
//
// Returns (dstBuf, tailBuf).
//
// maxLineLen limits the maximum length of a single line.
//
// It is expected that read timeout on r exceeds 1 second.
func ReadLinesBlockExt(r io.Reader, dstBuf, tailBuf []byte, maxLineLen int) ([]byte, []byte, error) {
startTime := time.Now()
if cap(dstBuf) < defaultBlockSize {
dstBuf = bytesutil.ResizeNoCopyNoOverallocate(dstBuf, defaultBlockSize)
}
dstBuf = append(dstBuf[:0], tailBuf...)
tailBuf = tailBuf[:0]
again:
n, err := r.Read(dstBuf[len(dstBuf):cap(dstBuf)])
// Check for error only if zero bytes read from r, i.e. no forward progress made.
// Otherwise process the read data.
if n == 0 {
if err == nil {
return dstBuf, tailBuf, fmt.Errorf("no forward progress made")
}
isEOF := isEOFLikeError(err)
if isEOF && len(dstBuf) > 0 {
// Missing newline in the end of stream. This is OK,
// so suppress io.EOF for now. It will be returned during the next
// call to ReadLinesBlock.
// This fixes https://github.com/VictoriaMetrics/VictoriaMetrics/issues/60 .
return dstBuf, tailBuf, nil
}
if !isEOF {
err = fmt.Errorf("cannot read a block of data in %.3fs: %w", time.Since(startTime).Seconds(), err)
} else {
err = io.EOF
}
return dstBuf, tailBuf, err
}
dstBuf = dstBuf[:len(dstBuf)+n]
// Search for the last newline in dstBuf and put the rest into tailBuf.
nn := bytes.LastIndexByte(dstBuf[len(dstBuf)-n:], '\n')
if nn < 0 {
// Didn't find at least a single line.
if len(dstBuf) > maxLineLen {
return dstBuf, tailBuf, fmt.Errorf("too long line: more than %d bytes", maxLineLen)
}
if cap(dstBuf) < 2*len(dstBuf) {
// Increase dsbBuf capacity, so more data could be read into it.
dstBufLen := len(dstBuf)
dstBuf = bytesutil.ResizeWithCopyNoOverallocate(dstBuf, 2*cap(dstBuf))
dstBuf = dstBuf[:dstBufLen]
}
goto again
}
// Found at least a single line. Return it.
nn += len(dstBuf) - n
tailBuf = append(tailBuf[:0], dstBuf[nn+1:]...)
dstBuf = dstBuf[:nn]
return dstBuf, tailBuf, nil
}
func isEOFLikeError(err error) bool {
if errors.Is(err, io.EOF) || errors.Is(err, io.ErrUnexpectedEOF) {
return true
}
s := err.Error()
return strings.Contains(s, "reset by peer")
}