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https://issues.apache.org/jira/browse/IGNITE-12543?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17061585#comment-17061585
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Aleksey Plekhanov commented on IGNITE-12543:
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[~Pavlukhin] when we marshal {{List<Object>}} on thin client side there is no
size overhead. Overhead appears on the server-side when we unmarshal (with keep
binary) byte array to {{List<BinaryObject>}} and marshal it again. Each binary
object after unmarshalling refers to the same full byte array (with offset and
length), then this byte array is copied for each object by
{{doWriteBinaryObject}} method during second marshaling. If we will avoid
double marshaling, the object will be stored in the form thin client marshal it
(without size grow) and then transferred back to the thin client in the same
form. So, yes, number of bytes transferred over the wire will be adequate after
fixing IGNITE-12625
> When put List<List<SomeObject>>, the data was increased much larger.
> --------------------------------------------------------------------
>
> Key: IGNITE-12543
> URL: https://issues.apache.org/jira/browse/IGNITE-12543
> Project: Ignite
> Issue Type: Bug
> Components: thin client
> Affects Versions: 2.6
> Reporter: LEE PYUNG BEOM
> Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> I use Ignite 2.6 version of Java Thin Client.
>
> When I put data in the form List<List<SomeObject>>,
> The size of the original 200KB data was increased to 50MB when inquired by
> Ignite servers.
> On the Heap Dump, the list element was repeatedly accumulated, increasing the
> data size.
>
> When I checked org.apacheignite.internal.binary.BinaryWriterExImpl.java
> doWriteBinaryObject() method,
> {code:java}
> // org.apacheignite.internal.binary.BinaryWriterExImpl.java
> public void doWriteBinaryObject(@Nullable BinaryObjectImpl po) {
> if (po == null)
> out.writeByte(GridBinaryMarshaller.NULL);
> else {
> byte[] poArr = po.array();
> out.unsafeEnsure(1 + 4 + poArr.length +4);
> out.unsafeWriteByte(GridBinaryMarshaller.BINARY_OBJ);
> out.unsafeWriteInt(poArr.length);
> out.writeByteArray(poArr);
> out.unsafeWriteInt(po.start());
> }
> }
> {code}
>
> The current Ignite implementation for storing data in the form
> List<List<Some_Objectject>> is:
> In the Marshalling stage, for example, data the size of List(5
> members)<List(10 members)<Some_Object(size:200 KB)> is:
> As many as 10*5 of the list's elements are duplicated.
> If the above data contains five objects of 200KB size, ten by one,
> 50 iterations are stored and 200K*10**5 = 100MB of data is used for cache and
> transfer.
> As a result of this increase in data size, it is confirmed that the failure
> of OOM, GC, etc. is caused by occupying Heap memory.
> Unnecessarily redundant data is used for cache storage and network transport.
> When looking up cache data, only some of the data at the top is read based on
> file location information from the entire data, so that normal data is
> retrieved.
> The way we're implemented today is safe from basic behavior, but we're
> wasting memory and network unnecessarily using inefficient algorithms
> This can have very serious consequences. Please check.
>
>
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