lib/protoparser: use all the available CPU cores for processing ingested data from a single /api/v1/import stream

Previously a single data ingestion stream to /api/v1/import could load only a single CPU core.

docs/Single-server-VictoriaMetrics.md

@@ -822,9 +822,6 @@ For example, `/api/v1/import?extra_label=foo=bar` would add `"foo":"bar"` label
 
 Note that it could be required to flush response cache after importing historical data. See [these docs](#backfilling) for detail.
 
-Each request to `/api/v1/import` can load up to a single vCPU core on VictoriaMetrics. Import speed can be improved by splitting the original file into smaller parts
-and importing them concurrently. Note that the original file must be split on newlines.
-
 
 ### Relabeling
 

lib/protoparser/vmimport/streamparser.go

@@ -1,6 +1,7 @@
 package vmimport
 
 import (
+	"bufio"
 	"fmt"
 	"io"
 	"net/http"
@@ -9,17 +10,20 @@ import (
 
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/common"
 	"github.com/VictoriaMetrics/metrics"
 )
 
-var maxLineLen = flagutil.NewBytes("import.maxLineLen", 100*1024*1024, "The maximum length in bytes of a single line accepted by /api/v1/import")
+var maxLineLen = flagutil.NewBytes("import.maxLineLen", 100*1024*1024, "The maximum length in bytes of a single line accepted by /api/v1/import; "+
+	"the line length can be limited with `max_rows_per_line` query arg passed to /api/v1/export")
 
 // ParseStream parses /api/v1/import lines from req and calls callback for the parsed rows.
 //
 // The callback can be called multiple times for streamed data from req.
 //
 // callback shouldn't hold rows after returning.
+// callback is called from multiple concurrent goroutines.
 func ParseStream(req *http.Request, callback func(rows []Row) error) error {
 	r := req.Body
 	if req.Header.Get("Content-Encoding") == "gzip" {
@@ -30,13 +34,45 @@ func ParseStream(req *http.Request, callback func(rows []Row) error) error {
 		defer common.PutGzipReader(zr)
 		r = zr
 	}
+	// By default req.Body uses 4Kb buffer. This size is too small for typical request to /api/v1/import,
+	// so use slightly bigger buffer in order to reduce read syscall overhead.
+	br := bufio.NewReaderSize(r, 1024*1024)
+
+	// Start gomaxprocs workers for processing the parsed data in parallel.
+	gomaxprocs := runtime.GOMAXPROCS(-1)
+	workCh := make(chan *unmarshalWork, 8*gomaxprocs)
+	var wg sync.WaitGroup
+	defer func() {
+		close(workCh)
+		wg.Wait()
+	}()
+	wg.Add(gomaxprocs)
+	for i := 0; i < gomaxprocs; i++ {
+		go func() {
+			defer wg.Done()
+			for uw := range workCh {
+				uw.rows.Unmarshal(bytesutil.ToUnsafeString(uw.reqBuf))
+				rows := uw.rows.Rows
+				for i := range rows {
+					row := &rows[i]
+					rowsRead.Add(len(row.Timestamps))
+				}
+				if err := callback(rows); err != nil {
+					logger.Errorf("error when processing imported data: %s", err)
+					putUnmarshalWork(uw)
+					continue
+				}
+				putUnmarshalWork(uw)
+			}
+		}()
+	}
 
 	ctx := getStreamContext()
 	defer putStreamContext(ctx)
-	for ctx.Read(r) {
-		if err := callback(ctx.Rows.Rows); err != nil {
-			return err
-		}
+	for ctx.Read(br) {
+		uw := getUnmarshalWork()
+		uw.reqBuf = append(uw.reqBuf[:0], ctx.reqBuf...)
+		workCh <- uw
 	}
 	return ctx.Error()
 }
@@ -54,8 +90,6 @@ func (ctx *streamContext) Read(r io.Reader) bool {
 		}
 		return false
 	}
-	ctx.Rows.Unmarshal(bytesutil.ToUnsafeString(ctx.reqBuf))
-	rowsRead.Add(len(ctx.Rows.Rows))
 	return true
 }
 
@@ -66,7 +100,6 @@ var (
 )
 
 type streamContext struct {
-	Rows    Rows
 	reqBuf  []byte
 	tailBuf []byte
 	err     error
@@ -80,7 +113,6 @@ func (ctx *streamContext) Error() error {
 }
 
 func (ctx *streamContext) reset() {
-	ctx.Rows.Reset()
 	ctx.reqBuf = ctx.reqBuf[:0]
 	ctx.tailBuf = ctx.tailBuf[:0]
 	ctx.err = nil
@@ -109,3 +141,28 @@ func putStreamContext(ctx *streamContext) {
 
 var streamContextPool sync.Pool
 var streamContextPoolCh = make(chan *streamContext, runtime.GOMAXPROCS(-1))
+
+type unmarshalWork struct {
+	rows   Rows
+	reqBuf []byte
+}
+
+func (uw *unmarshalWork) reset() {
+	uw.rows.Reset()
+	uw.reqBuf = uw.reqBuf[:0]
+}
+
+func getUnmarshalWork() *unmarshalWork {
+	v := unmarshalWorkPool.Get()
+	if v == nil {
+		return &unmarshalWork{}
+	}
+	return v.(*unmarshalWork)
+}
+
+func putUnmarshalWork(uw *unmarshalWork) {
+	uw.reset()
+	unmarshalWorkPool.Put(uw)
+}
+
+var unmarshalWorkPool sync.Pool