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From Stack <st...@duboce.net>
Subject Re: Strange problem while scanning HBase table with PIG
Date Sun, 11 Dec 2011 22:41:27 GMT
On Sat, Dec 10, 2011 at 9:51 AM, Luis A. Sarmento
<luis-a-sarmento@telecom.pt> wrote:
> Now, this *only happens for one mapper* --> mapper_0
> No matter how I change my scanning parameters - different begin / end timestamp; more
data vs less data; change caching ,etc.. - , it is always ends up like this: mapper 0 fails,
even when 500 hundreds other succeed.

Could this mapper have a massive record in it or be full of deletes,
so many deletes, it takes > 60 seconds to traverse them.

You have a lease expired going on.  This happens because either client
is taking > 60 second before it goes back to the server (server-side,
the scan lease has expired) or we're down in the depths of the server
traversing data looking for something to return and this is going on
longer than 60 seconds.

Scan the mapper_0 range and see what comes back.

Could change the client cache size too.  Perhaps you are getting lots
of rows on each invocation, so many rows, its taking you a while to
process the all?  This section of book has some notes that might be of
use: http://hbase.apache.org/book.html#perf.reading

Add logging?  See if its server-side or client-side problem?


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