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Re-use gzip writers in a pool

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Since they allocate sizeable chunks of memory, this can save on garbage-collection.
This commit is contained in:
Bryan Boreham
2018-07-08 16:30:04 +00:00
parent 777360dc9e
commit 70cd79307e
2 changed files with 14 additions and 13 deletions
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3
extras/copyreport/main.go
View File

@@ -2,7 +2,6 @@
package main
import (
"compress/gzip"
"flag"
"log"
@@ -20,7 +19,7 @@ func main() {
if err != nil {
log.Fatal(err)
}
if err = rpt.WriteToFile(flag.Arg(1), gzip.DefaultCompression); err != nil {
if err = rpt.WriteToFile(flag.Arg(1)); err != nil {
log.Fatal(err)
}
}

24
report/marshal.go
View File

@@ -39,11 +39,10 @@ func (StdoutPublisher) Publish(rep Report) error {
// WriteBinary writes a Report as a gzipped msgpack into a bytes.Buffer
func (rep Report) WriteBinary() (*bytes.Buffer, error) {
w := &bytes.Buffer{}
gzwriter, err := gzip.NewWriterLevel(w, gzip.DefaultCompression)
if err != nil {
return nil, err
}
if err = codec.NewEncoder(gzwriter, &codec.MsgpackHandle{}).Encode(&rep); err != nil {
gzwriter := gzipWriterPool.Get().(*gzip.Writer)
gzwriter.Reset(w)
defer gzipWriterPool.Put(gzwriter)
if err := codec.NewEncoder(gzwriter, &codec.MsgpackHandle{}).Encode(&rep); err != nil {
return nil, err
}
gzwriter.Close() // otherwise the content won't get flushed to the output stream
@@ -61,10 +60,14 @@ func (c byteCounter) Read(p []byte) (n int, err error) {
return n, err
}
// buffer pool to reduce garbage-collection
// buffer pools to reduce garbage-collection
var bufferPool = &sync.Pool{
New: func() interface{} { return new(bytes.Buffer) },
}
var gzipWriterPool = &sync.Pool{
// NewWriterLevel() only errors if the compression level is invalid, which can't happen here
New: func() interface{} { w, _ := gzip.NewWriterLevel(nil, gzip.DefaultCompression); return w },
}
// ReadBinary reads bytes into a Report.
//
@@ -169,7 +172,7 @@ func MakeFromFile(path string) (rpt Report, _ error) {
// WriteToFile writes a Report to a file. The encoding is determined
// by the file extension (".msgpack" or ".json", with an optional
// ".gz").
func (rep *Report) WriteToFile(path string, compressionLevel int) error {
func (rep *Report) WriteToFile(path string) error {
f, err := os.Create(path)
if err != nil {
return err
@@ -186,10 +189,9 @@ func (rep *Report) WriteToFile(path string, compressionLevel int) error {
defer bufwriter.Flush()
w = bufwriter
if gzipped {
gzwriter, err := gzip.NewWriterLevel(w, compressionLevel)
if err != nil {
return err
}
gzwriter := gzipWriterPool.Get().(*gzip.Writer)
gzwriter.Reset(w)
defer gzipWriterPool.Put(gzwriter)
defer gzwriter.Close()
w = gzwriter
}