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From Harsh J <ha...@cloudera.com>
Subject Re: Is Put() operation a synchronous call on server side?
Date Thu, 06 Dec 2012 14:06:05 GMT
Hi Yun,

Yes, a single Put call is safely synchronous in nature. A Put is
placed on the WAL, added to the MemStore, and then returned back as a
success to the client if all went well.

A Put does not directly go to disk, and gets flushed from the MemStore
based on regular flushing patterns or based on manual invocations of
flush called on its region or its table.

The path to follow is quite simple - A Put goes from a Client (HTable)
to a RegionServer (HRegionServer). You've already read the Client
areas, so if you read HRegionServer#put(…) method(s), which is the
server-end of it, you'll see the Server-RPC end of it.

On Thu, Dec 6, 2012 at 6:32 PM, yun peng <pengyunmomo@gmail.com> wrote:
> Hi, since on client side HBase can immediately send Put() by turning off
> setAutoFlush(), I am wondering if Put() in HBase server side is executed in
> synchronous way? Be a bit more specific, given a Put() that already arrives
> at HRegion, will it wait (or be blocking) until all put-related operations
> are done, such as write to WAL and write to memstore, or even flush to disk
> (though may not on every time). Or it just triggers put-related operations
> and immediately returns....
> Besides, in research of this problem, I found it not very easy to find the
> code that perform RPC in HBase, for example, how does client-side
> HTable.put() invoke the server-side HRegion.put().... Can anyone points to
> me the related code path on this regards? Thanks...
> regards,
> Yun

Harsh J

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