Can we just take a quick pause… John you wrote the following: "We have been running into an RPC deadlock issue on HBase and from investigation, we believe the root of the issue is in us doing cross region increments from a coprocessor. After some further searching and reading over this <http://mail-archives.apache.org/mod_mbox/hbase-user/201212.mbox/%3CCA+RK=_BP8k1Z-gQ+38RiipKgzi+=5cn3ekzdjz_z-2qt8xo...@mail.gmail.com%3E> we think that we can solve this by doing the increments locally on the region. "
Which goes back to some thing Andrew wrote concerning an RPC deadlock. Can either you or Andrew explain in detail what is meant by the RPC deadlock? This goes back to rethink how to implement coprocessors. On Oct 9, 2013, at 11:03 PM, John Weatherford <[email protected]> wrote: > Thank you ted. I might have to rethink my key design to accomodate this. With > this design and using the totals in keys as you suggested, I would have to > scan the entire "California" group to find the totals. Thank you very much > for your help. > > -John > > On Wed 09 Oct 2013 08:43:12 PM PDT, Ted Yu wrote: >> John: >> Suppose 'California-**12346' is the start key of region 1 and 'California-** >> 95424' is the start key of region 2. You can choose >> 'California-**12346#total' >> to be the row key where increment is done for region 1 and >> 'California-**95424#total' >> to be the row key where increment is done for region 2. >> >> w.r.t. verification of whether given row key is indeed inside the hosting >> region, see the following: >> >> void checkRow(final byte [] row, String op) throws IOException { >> >> if (!rowIsInRange(getRegionInfo(), row)) { >> >> throw new WrongRegionException("Requested row out of range for " + >> >> op + " on HRegion " + this + ", startKey='" + >> >> Cheers >> >> >> On Wed, Oct 9, 2013 at 8:26 PM, John Weatherford < >> [email protected]> wrote: >> >>> First, Thank you everyone for the quick response. >>> >>> Ted: >>> The custom split policy could be an interesting solution. Regarding the >>> other option you sent, if I pull the end row key, I could construct an end >>> key, but if I suffix the row key with the end key of the region, would that >>> actually solve my problem? In the contrived case, wouldn't the suffixed key >>> now be "California-total-California-**12346" and the other region's >>> counter would be "California-total-California-**95424" and both of these >>> keys would actually end up on the second region since the sorting of the >>> keys would impose that "California-t*" comes after "California-[1-9]". >>> >>> Part of the question is that I don't understand if calling >>> incrementColumnValue() on the region will always execute on the region >>> called, regardles of rowkey. If so, what happens when those regions are >>> merged? >>> >>> Thanks again for the help! >>> >>> >>> On Wed 09 Oct 2013 07:43:34 PM PDT, Ted Yu wrote: >>> >>>> bq. 'California-total' row in each region >>>> >>>> Of course such row key needs to be suffixed with either start or end key >>>> of >>>> the corresponding region. >>>> >>>> >>>> On Wed, Oct 9, 2013 at 7:39 PM, Ted Yu <[email protected]> wrote: >>>> >>>> John: >>>>> Looks like you need a 'California-total' row in each region. >>>>> >>>>> Custom Split Policy can help you achieve that, see 9.7.4.1 in: >>>>> http://hbase.apache.org/book.**html#d0e6541<http://hbase.apache.org/book.html#d0e6541> >>>>> >>>>> Cheers >>>>> >>>>> >>>>> On Wed, Oct 9, 2013 at 7:28 PM, Vladimir Rodionov < >>>>> [email protected] >>>>> >>>>>> wrote: >>>>>> >>>>> >>>>> Contrived Example >>>>>>>> >>>>>>> >>>>>> Insert rowkey "California-12345" triggers a coprocessor to call >>>>>>>> incrementColumnValue() with a rowkey of "California-total" all on >>>>>>>> >>>>>>> Region 1. >>>>>> >>>>>> This would likely be on an insert on the same region. But as the table >>>>>>>> grows, this secondary insert could end up on another region. If it is >>>>>>>> confined, then suppose we later insert "California-95424" which still >>>>>>>> triggers a call to incrementColumnValue() with a rowkey of >>>>>>>> "California-total" all on Region 2. >>>>>>>> >>>>>>> >>>>>> Are we now left with two rowkeys of "California-total"? One on each >>>>>>>> region server? If so, what happens if these two regions are compacted >>>>>>>> into one? >>>>>>>> >>>>>>> >>>>>> Best regards, >>>>>>>> >>>>>>> >>>>>> Nope, Your "California-total" will migrate to Region 2 after region >>>>>> split >>>>>> is complete. >>>>>> >>>>>> Vladimir Rodionov >>>>>> Principal Platform Engineer >>>>>> Carrier IQ, www.carrieriq.com >>>>>> e-mail: [email protected] >>>>>> >>>>>> ______________________________**__________ >>>>>> >>>>>> Confidentiality Notice: The information contained in this message, >>>>>> including any attachments hereto, may be confidential and is intended >>>>>> to be >>>>>> read only by the individual or entity to whom this message is >>>>>> addressed. If >>>>>> the reader of this message is not the intended recipient or an agent or >>>>>> designee of the intended recipient, please note that any review, use, >>>>>> disclosure or distribution of this message or its attachments, in any >>>>>> form, >>>>>> is strictly prohibited. If you have received this message in error, >>>>>> please >>>>>> immediately notify the sender and/or [email protected] and >>>>>> delete or destroy any copy of this message and its attachments. >>>>>> >>>>>> >>>>> >>>>> >>>> >> >
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