[jira] [Commented] (FLINK-5756) When there are many values under the same key in ListState, RocksDBStateBackend performances poor

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-5756?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15962314#comment-15962314 ] 

ASF GitHub Bot commented on FLINK-5756:
---------------------------------------

GitHub user rmetzger opened a pull request:

    https://github.com/apache/flink/pull/3704

    [FLINK-5756] Replace RocksDB dependency with FRocksDB

    @StefanRRichter has created a custom RocksDB release that fixes FLINK-5756.

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/rmetzger/flink flink5756

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/flink/pull/3704.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #3704
    
----
commit b05c595a37ea5b3a08ef4a11d9259eb7aabee005
Author: Robert Metzger <rm...@apache.org>
Date:   2017-04-09T20:05:08Z

    [FLINK-5756] Replace RocksDB dependency with FRocksDB

----


> When there are many values under the same key in ListState, RocksDBStateBackend performances poor
> -------------------------------------------------------------------------------------------------
>
>                 Key: FLINK-5756
>                 URL: https://issues.apache.org/jira/browse/FLINK-5756
>             Project: Flink
>          Issue Type: Improvement
>          Components: State Backends, Checkpointing
>    Affects Versions: 1.2.0
>         Environment: CentOS 7.2
>            Reporter: Syinchwun Leo
>
> When using RocksDB as the StateBackend, if there are many values under the same key in ListState, the windowState.get() operator performances very poor. I also the the RocksDB using version 4.11.2, the performance is also very poor. The problem is likely to related to RocksDB itself's get() operator after using merge(). The problem may influences the window operation's performance when the size is very large using ListState. I try to merge 50000 values under the same key in RocksDB, It costs 120 seconds to execute get() operation.
> ///////////////////////////////////////////////////////////////////////////////
> The flink's code is as follows:    
> {code}
> class SEventSource extends RichSourceFunction [SEvent] {
>   private var count = 0L
>   private val alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWZYX0987654321"
>   override def run(sourceContext: SourceContext[SEvent]): Unit = {
>     while (true) {
>       for (i <- 0 until 5000) {
>         sourceContext.collect(SEvent(1, "hello-"+count, alphabet,1))
>         count += 1L
>       }
>       Thread.sleep(1000)
>     }
>   }
> }
> env.addSource(new SEventSource)
>       .assignTimestampsAndWatermarks(new AssignerWithPeriodicWatermarks[SEvent] {
>         override def getCurrentWatermark: Watermark = {
>           new Watermark(System.currentTimeMillis())
>         }
>         override def extractTimestamp(t: SEvent, l: Long): Long = {
>           System.currentTimeMillis()
>         }
>       })
>       .keyBy(0)
>       .window(SlidingEventTimeWindows.of(Time.seconds(20), Time.seconds(2)))
>       .apply(new WindowStatistic)
>       .map(x => (System.currentTimeMillis(), x))
>       .print()
> {code}
> ////////////////////////////////////
> The RocksDB Test code:    
> {code}
> val stringAppendOperator = new StringAppendOperator
>     val options = new Options()
>     options.setCompactionStyle(CompactionStyle.LEVEL)
>       .setCompressionType(CompressionType.SNAPPY_COMPRESSION)
>       .setLevelCompactionDynamicLevelBytes(true)
>       .setIncreaseParallelism(4)
>       .setUseFsync(true)
>       .setMaxOpenFiles(-1)
>       .setCreateIfMissing(true)
>       .setMergeOperator(stringAppendOperator)
>     val write_options = new WriteOptions
>     write_options.setSync(false)
>     val rocksDB = RocksDB.open(options, "/******/Data/")
>     val key = "key"
>     val value = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ7890654321"
>     val beginmerge = System.currentTimeMillis()
>     for(i <- 0 to 50000) {
>       rocksDB.merge(key.getBytes(), ("s"+ i + value).getBytes())
>       //rocksDB.put(key.getBytes, value.getBytes)
>     }
>     println("finish")
>     val begin = System.currentTimeMillis()
>     rocksDB.get(key.getBytes)
>     val end = System.currentTimeMillis()
>     println("merge cost:" + (begin - beginmerge))
>     println("Time consuming:" + (end - begin))
>   }
> }
> {code}



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