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From yun peng <pengyunm...@gmail.com>
Subject Re: Is Put() operation a synchronous call on server side?
Date Thu, 06 Dec 2012 18:32:48 GMT
Hi, Dong and Harsh, thanks for your detailed explanations. Based on Dong's
answers, I summarise the call path a little bit.
I think there are some scheduling overheads in ExecutorService.submit().

Dong, I didn't find any code related to protobuf, and my codebase is on
HBase0.94.2. Maybe I have not use the most up-to-date version. By the way,
I have an other and somewhat related question, but I will post in a
seperate thread.

On Thu, Dec 6, 2012 at 9:06 AM, Harsh J <harsh@cloudera.com> wrote:

> 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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