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https://issues.apache.org/jira/browse/FLINK-26585?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Hangxiang Yu reassigned FLINK-26585:
------------------------------------
Assignee: Matthias Schwalbe
> State Processor API: Loading a state set buffers the whole state set in
> memory before starting to process
> ---------------------------------------------------------------------------------------------------------
>
> Key: FLINK-26585
> URL: https://issues.apache.org/jira/browse/FLINK-26585
> Project: Flink
> Issue Type: Improvement
> Components: API / State Processor
> Affects Versions: 1.13.0, 1.14.0, 1.15.0
> Reporter: Matthias Schwalbe
> Assignee: Matthias Schwalbe
> Priority: Major
> Attachments: MultiStateKeyIteratorNoStreams.java
>
>
> * When loading a state, MultiStateKeyIterator load and bufferes the whole
> state in memory before it event processes a single data point
> ** This is absolutely no problem for small state (hence the unit tests work
> fine)
> ** MultiStateKeyIterator ctor sets up a java Stream that iterates all state
> descriptors and flattens all datapoints contained within
> ** The java.util.stream.Stream#flatMap function causes the buffering of the
> whole data set when enumerated later on
> ** See call stack [1]
> *** I our case this is 150e6 data points (> 1GiB just for the pointers to
> the data, let alone the data itself ~30GiB)
> ** I’m not aware of some instrumentation of Stream in order to avoid the
> problem, hence
> ** I coded an alternative implementation of MultiStateKeyIterator that
> avoids using java Stream,
> ** I can contribute our implementation (MultiStateKeyIteratorNoStreams)
> [1]
> Streams call stack:
> hasNext:77, RocksStateKeysIterator
> (org.apache.flink.contrib.streaming.state.iterator)
> next:82, RocksStateKeysIterator
> (org.apache.flink.contrib.streaming.state.iterator)
> forEachRemaining:116, Iterator (java.util)
> forEachRemaining:1801, Spliterators$IteratorSpliterator (java.util)
> forEach:580, ReferencePipeline$Head (java.util.stream)
> accept:270, ReferencePipeline$7$1 (java.util.stream)
> # <R> Stream<R> flatMap(final Function<? super P_OUT, ? extends
> Stream<? extends R>> var1)
> accept:373, ReferencePipeline$11$1 (java.util.stream)
> # Stream<P_OUT> peek(final Consumer<? super P_OUT> var1)
> accept:193, ReferencePipeline$3$1 (java.util.stream)
> # <R> Stream<R> map(final Function<? super P_OUT, ? extends R>
> var1)
> tryAdvance:1359, ArrayList$ArrayListSpliterator (java.util)
> lambda$initPartialTraversalState$0:294,
> StreamSpliterators$WrappingSpliterator (java.util.stream)
> getAsBoolean:-1, 1528195520
> (java.util.stream.StreamSpliterators$WrappingSpliterator$$Lambda$57)
> fillBuffer:206, StreamSpliterators$AbstractWrappingSpliterator
> (java.util.stream)
> doAdvance:161, StreamSpliterators$AbstractWrappingSpliterator
> (java.util.stream)
> tryAdvance:300, StreamSpliterators$WrappingSpliterator (java.util.stream)
> hasNext:681, Spliterators$1Adapter (java.util)
> hasNext:83, MultiStateKeyIterator (org.apache.flink.state.api.input)
> hasNext:162, KeyedStateReaderOperator$NamespaceDecorator
> (org.apache.flink.state.api.input.operator)
> reachedEnd:215, KeyedStateInputFormat (org.apache.flink.state.api.input)
> invoke:191, DataSourceTask (org.apache.flink.runtime.operators)
> doRun:776, Task (org.apache.flink.runtime.taskmanager)
> run:563, Task (org.apache.flink.runtime.taskmanager)
> run:748, Thread (java.lang)
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