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Improve image pull performance from http 1.1 container registries

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Private registries that does not support http 2.0 such as Azure Container Registry streams back content in a max of 16KB chunks (max TLS record size). The small chunks introduce an overhead when copying the layers to the content store sine each chunk incurs the overhead of  grpc message that has to be sent to the content store.

This change reduces this overhead by buffering the chunks into 1MB chunks and only then writes a message to the content store.

Below is a per comparsion between the 2 approaches using a couple of large images that are being pulled from the docker hub (http 2.0) and a private Azure CR (http 1.1) in seconds.

image                                                   | Buffered copy | master
-------                                                 |---------------|----------
docker.io/pytorch/pytorch:latest                        |  55.63        | 58.33
docker.io/nvidia/cuda:latest                            |  72.05        | 75.98
containerdpulltest.azurecr.io/pytorch/pytorch:latest    | 61.45         | 77.1
containerdpulltest.azurecr.io/nvidia/cuda:latest        | 77.13         | 85.47

Signed-off-by: Amr Mahdi <amramahdi@gmail.com>
This commit is contained in:
Amr Mahdi 2020-10-26 04:46:48 +00:00
parent 656b487d33
commit 289130b8a7
1 changed files with 26 additions and 3 deletions
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29
content/helpers.go
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@ -230,8 +230,31 @@ func seekReader(r io.Reader, offset, size int64) (io.Reader, error) {
} }
func copyWithBuffer(dst io.Writer, src io.Reader) (written int64, err error) { func copyWithBuffer(dst io.Writer, src io.Reader) (written int64, err error) {
buf := bufPool.Get().(*[]byte) bufRef := bufPool.Get().(*[]byte)
written, err = io.CopyBuffer(dst, src, *buf) defer bufPool.Put(bufRef)
bufPool.Put(buf) buf := *bufRef
for {
nr, er := io.ReadAtLeast(src, buf, len(buf))
if nr > 0 {
nw, ew := dst.Write(buf[0:nr])
if nw > 0 {
written += int64(nw)
}
if ew != nil {
err = ew
break
}
if nr != nw {
err = io.ErrShortWrite
break
}
}
if er != nil {
if er != io.EOF && er != io.ErrUnexpectedEOF {
err = er
}
break
}
}
return return
} }