Victsm commented on a change in pull request #29855:
URL: https://github.com/apache/spark/pull/29855#discussion_r501241665
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File path:
common/network-common/src/main/java/org/apache/spark/network/server/TransportRequestHandler.java
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@@ -181,6 +182,17 @@ public void onFailure(Throwable e) {
private void processStreamUpload(final UploadStream req) {
assert (req.body() == null);
try {
+ // Retain the original metadata buffer, since it will be used during the
invocation of
+ // this method. Will be released later.
+ req.meta.retain();
+ // Make a copy of the original metadata buffer. In benchmark, we noticed
that
+ // we cannot respond the original metadata buffer back to the client,
otherwise
+ // in cases where multiple concurrent shuffles are present, a wrong
metadata might
+ // be sent back to client. This is related to the eager release of the
metadata buffer,
+ // i.e., we always release the original buffer by the time the
invocation of this
+ // method ends, instead of by the time we respond it to the client. This
is necessary,
+ // otherwise we start seeing memory issues very quickly in benchmarks.
+ ByteBuffer meta = cloneBuffer(req.meta.nioByteBuffer());
Review comment:
Spark does not do this previously, i.e. creating large number of
callbacks.
This occurs in the Spark executor side, not in the shuffle service side
though.
We are in the process of benchmarking this to see if there's any visible
impact.
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