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https://issues.apache.org/jira/browse/HBASE-13071?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14330005#comment-14330005
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stack commented on HBASE-13071:
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[~eshcar] Design doc looks straightforward... no continental shifts going on
here. One question for you is if you are 'up' on all that has gone on in this
space previous? If not, let me dig it up for you (In particular, an experiment
that added faux streaming via a hacked up new port on the server that allowed
client via a new channel get a KV/Cell at a time with nice improvements in
throughput....)
On 'hbase.client.scanner.async.prefetch=true', let me suggest that default is
that this feature is on, not off, by default. Why would you want current
behavior if this is available. In fact, IMO, don't bother offering this config
presuming the throughput is better after this change as I expect it wil be.
> Hbase Streaming Scan Feature
> ----------------------------
>
> Key: HBASE-13071
> URL: https://issues.apache.org/jira/browse/HBASE-13071
> Project: HBase
> Issue Type: New Feature
> Reporter: Eshcar Hillel
> Attachments: HBaseStreamingScanDesign.pdf
>
>
> A scan operation iterates over all rows of a table or a subrange of the
> table. The synchronous nature in which the data is served at the client side
> hinders the speed the application traverses the data: it increases the
> overall processing time, and may cause a great variance in the times the
> application waits for the next piece of data.
> The scanner next() method at the client side invokes an RPC to the
> regionserver and then stores the results in a cache. The application can
> specify how many rows will be transmitted per RPC; by default this is set to
> 100 rows.
> The cache can be considered as a producer-consumer queue, where the hbase
> client pushes the data to the queue and the application consumes it.
> Currently this queue is synchronous, i.e., blocking. More specifically, when
> the application consumed all the data from the cache --- so the cache is
> empty --- the hbase client retrieves additional data from the server and
> re-fills the cache with new data. During this time the application is blocked.
> Under the assumption that the application processing time can be balanced by
> the time it takes to retrieve the data, an asynchronous approach can reduce
> the time the application is waiting for data.
> We attach a design document.
> We also have a patch that is based on a private branch, and some evaluation
> results of this code.
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