On Thu, Sep 10, 2015 at 4:26 PM, Eric Owhadi <eric.owh...@esgyn.com> wrote:
> Not sure I understand. I was not planning to do any patch on an HBase > distro? Only on apache hbase 2.0 and get automatic distro vendor adoption? > Reason is that for trafodion, the trafodion patch would already cover Hbase > 1.0. (and probably 1.1 too since Hortonworks will jump to 1.1 directly if I > understand correctly). > So I was thinking to get a HBase 2.0 fixed, and make sure that it makes it > in the future official distros that will be on hbase 2.0. At that point > Trafodion patch would be removed. I am not sure Trafodion will support > HBase > 1.2, probably it will jump to 2.0 directly? Given that trafodion uses some > low level non "stable" API for transactional support, there can be some > work > involved to support minor versions or patch that could change API ... > > Also fix 2.0 would be simpler to do, as it will not be optional, should > just > be a few line of code deletion, right? > A 1.x fix would be enabled/disabled via hbase-site.xml? Or where you > thinking on a per call basis with a new flag in scan object? > Make sense? > Sorry. Wasn't implying you'd do distro fixes. Didn't mean to confuse. Above sounds good. St.Ack > Eric > > -----Original Message----- > From: saint....@gmail.com [mailto:saint....@gmail.com] On Behalf Of Stack > Sent: Thursday, September 10, 2015 5:49 PM > To: HBase Dev List <dev@hbase.apache.org> > Subject: Re: Question on hbase.client.scanner.timeout.period > > Suggest you do apache hbase first. You have a chance of getting it into 1.2 > if you do it soon. You might get a review too. Vendors generally want patch > upstream first before backporting. If up in apache hbase, they might pull > it > back in a patch release if it doesn't break anything and it makes user or > partner life smoother. > > Just a suggestion, > St.Ack > > > On Thu, Sep 10, 2015 at 3:14 PM, Eric Owhadi <eric.owh...@esgyn.com> > wrote: > > > Not yes, I am waiting our QA validation on the patched trafodion and > > see if we are not finding side effects to then work on an hbase 2.0 > > patch and create the umbrella jira as you suggested. > > Except if you think I should rush on 2.0 to make sure it makes it to > > any future official Hbase distro shipping with 2.0? > > > > Eric > > > > > > -----Original Message----- > > From: saint....@gmail.com [mailto:saint....@gmail.com] On Behalf Of > > Stack > > Sent: Thursday, September 10, 2015 4:23 PM > > To: HBase Dev List <dev@hbase.apache.org> > > Subject: Re: Question on hbase.client.scanner.timeout.period > > > > You have a patch for apache hbase Eric? Is there an apache hbase issue > > to add this in? > > St.Ack > > > > On Thu, Sep 10, 2015 at 10:21 AM, Eric Owhadi <eric.owh...@esgyn.com> > > wrote: > > > > > Thanks for pointing me to HBase-13333, it is indeed supposed to > > > address the very same problem. With the drawback of requiring client > > > side involvement, of asynchronous nature. I still have not > > > discovered any reason why just doing it the way I proposed would > > > lead to any negative side effect. Must admit I feel uncomfortable > > > since the patch is just about removing code that usually is added with > a > > > purpose :-). > > > We have not yet run full QA, but at least 100% of trafodion > > > regression test pass. > > > As for when the patch will make it to trafodion, given that I did it > > > only for a CDH build of Trafodion with HBase 1.0 support, I still > > > cannot check it in (trafodion is still on .98 and builds OK for > > > Cloudera,Hortonworks,Mapr and Apache). Trafodion would first need to > > > have full support for HBase 1.0 for all Hadoop distro we support, > > > then I will need to redo the patch that is distro specific, and make > > > sure the build process deals with this... It is my plan to do so... > > > Hoping that I do not discover any issue with other distro (like > > > private attributes or functions that I cannot circumvent... but that > > > would just mean that the patch would not be available for a specific > > > distro) > > > Eric > > > > > > > > > -----Original Message----- > > > From: Jerry He [mailto:jerry...@gmail.com] > > > Sent: Saturday, September 5, 2015 1:47 PM > > > To: dev <dev@hbase.apache.org> > > > Subject: Re: Question on hbase.client.scanner.timeout.period > > > > > > You can take a look at HBASE-13333: Renew Scanner Lease without > > > advancing the RegionScanner, which may be helpful in this kind of > > > case Your proposal sounds like a good alternative approach as well. > > > We should add that JIRA to the blog link Stack mentioned. > > > > > > Jerry > > > > > > On Sat, Sep 5, 2015 at 9:07 AM, Stack <st...@duboce.net> wrote: > > > > > > > On Fri, Sep 4, 2015 at 5:06 PM, Eric Owhadi > > > > <eric.owh...@esgyn.com> > > > wrote: > > > > > > > > > OK so to answer the "is it easy to insert the patched scanner > > > > > for trafodion", the answer is no. > > > > > > > > > > > > > I suspected this. > > > > > > > > > > > > > > > > > Was easier on .98, but on 1.0 it was quite a challenge. All > > > > > about dealing with private attributes instead of protected that > > > > > are not visible to the PatchClentScanner class that extends > > > > > ClientScanner. > > > > > Currently running the regression tests to see if there is no > > > > > side > > > > effect... > > > > > Was able to demonstrate with breakpoint on next() waiting more > > > > > than > > > > > 1 mn (the default lease timeout value) that with the patch > > > > > things gracefully reset and all is good, no row skipped or > > > > > duplicated, while without, I get the Scanner time out exception. > > > > > Patch can be turn on or off with a new > > > > key > > > > > in hbase-site.xml... > > > > > I will feel better when this will be deprecated :-). > > > > > > > > > > > > > Smile. > > > > > > > > Excellent. You have a patch for us then Eric? Sounds like the > > > > interjection of your new Scanner would be for pre-2.0. For 2.0 we > > > > should just turn on this behavior as the default. > > > > > > > > Thanks, > > > > St.Ack > > > > > > > > > > > > > > > > > Eric Owhadi > > > > > > > > > > -----Original Message----- > > > > > From: saint....@gmail.com [mailto:saint....@gmail.com] On Behalf > > > > > Of > > > > Stack > > > > > Sent: Friday, August 28, 2015 6:35 PM > > > > > To: HBase Dev List <dev@hbase.apache.org> > > > > > Subject: Re: Question on hbase.client.scanner.timeout.period > > > > > > > > > > On Fri, Aug 28, 2015 at 11:31 AM, Eric Owhadi > > > > > <eric.owh...@esgyn.com> > > > > > wrote: > > > > > > > > > > > That sounds good, but given trafodion needs to work on current > > > > > > and future released version of HBase, unpatched, I will first > > > > > > implement a ClientScannerTrafodion (to be deprecated), > > > > > > inheriting from ClientScanner that will just overload the > > > > > > loadCache(),and make sure that the code that is picking up the > > > > > > right scanner based on scan object is bypassed to force > > > > > > getting the ClientScannerTrafodion when appropriate. > > > > > > Not very elegant, but need to take into consideration > > > > > > trafodion deployment requirements. > > > > > > Then, if we do not discover any side effect during our QA > > > > > > related to this code I will port the fix on HBase to deprecate > > > > > > the custom scanner (probably first on HBase 2.0, then will let > > > > > > the community decide if this fix is worth it for back > > > > > > porting...). It will be a first for me, but that's great, I'll > > > > > > take your offer to help ;-)... > > > > > > > > > > > > > > > > Sweet. Suggest opening an umbrellas issue in hbase to implement > > > > > this feature. Reference HBASE-2161 (it is closed now). Link > > > > > trafodion issue to it. A subtask could have implementation in > > > > > hbase 2.0, another could be backport. > > > > > > > > > > Is is easy to insert your T*ClientScanner? > > > > > St.Ack > > > > > > > > > > > > > > > > > > > > > Regards, > > > > > > Eric > > > > > > > > > > > > -----Original Message----- > > > > > > From: saint....@gmail.com [mailto:saint....@gmail.com] On > > > > > > Behalf Of Stack > > > > > > Sent: Thursday, August 27, 2015 3:55 PM > > > > > > To: HBase Dev List <dev@hbase.apache.org> > > > > > > Subject: Re: Question on hbase.client.scanner.timeout.period > > > > > > > > > > > > On Thu, Aug 27, 2015 at 1:39 PM, Eric Owhadi > > > > > > <eric.owh...@esgyn.com> > > > > > > wrote: > > > > > > > > > > > > > Oops, my bad, the related JIRA was : > > > > > > > https://issues.apache.org/jira/browse/HBASE-2161 > > > > > > > > > > > > > > I am suggesting that the special code client side in > > > > > > > loadCache() of ClientScanner that is trapping the > > > > > > > UnknownScannerException, then on purpose check if it is > > > > > > > coming from a lease timeout (and not by a region move) to > > > > > > > decide that it would throw a ScannerTimeoutException instead > > > > > > > of letting the code go and just reset the scanner and start > > > > > > > from last successful retrieve (the way it works for an > > > > > > > unknowScannerException due to a region moving). > > > > > > > By just removing the special handling that tries to > > > > > > > differentiate from unkownScannerException due to lease > > > > > > > timeout, we should have a resolution to JIRA 2161- And to > > > > > > > our trafodion issue. > > > > > > > > > > > > > > We are still protecting against dead client that would cause > > > > > > > resource leak at region server, since we keep the lease > > > > > > > timeout mechanism. > > > > > > > > > > > > > > Not sure if I have overlooked something, as usually, code is > > > > > > > here for a reason :-)... > > > > > > > > > > > > > > > > > > > > Your proposal sounds good to me. > > > > > > > > > > > > Scanner works the way it does because it has always work this > > > > > > way > > > > > (smile). > > > > > > A while back, one of the lads suggested we do like dynamodb > > > > > > and have scanner have no state on the serverside, the scan > > > > > > next would just supply all necessary context. It was argued > > > > > > against because serverside setup is so costly. Your suggestion > > > > > > is similar only we do it only if Scanner has timed out. > > > > > > > > > > > > Suggest we keep the current semantic in 1.x at least. We could > > > > > > flip to your behavior in 2.x. Meantime, you'd have to ask for > > > > > > it when you set up your Scan object by setting a flag. > > > > > > > > > > > > Would that work? If you want to have a go at it, I could help > > > > > > out on the issue. > > > > > > > > > > > > St.Ack > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Regards, > > > > > > > Eric > > > > > > > > > > > > > > > > > > > > > > > > > > > > -----Original Message----- > > > > > > > From: saint....@gmail.com [mailto:saint....@gmail.com] On > > > > > > > Behalf Of Stack > > > > > > > Sent: Thursday, August 27, 2015 3:23 PM > > > > > > > To: HBase Dev List <dev@hbase.apache.org> > > > > > > > Subject: Re: Question on hbase.client.scanner.timeout.period > > > > > > > > > > > > > > On Tue, Aug 25, 2015 at 8:03 AM, Eric Owhadi > > > > > > > <eric.owh...@esgyn.com> > > > > > > > wrote: > > > > > > > > > > > > > > > Hello St.Ack, > > > > > > > > Thanks for your pointer, but I had already investigated > > > > > > > > JIRA > > > > > > > > https://issues.apache.org/jira/browse/HBASE-13090 > > > > > > > > Unfortunately, this heartbeat will protect against rpc > > > > > > > > timeout, not server side lease timeout that we are > > > > > > > > experiencing right now. > > > > > > > > I have not seen an active JIRA fixing our issue. > > > > > > > > Only https://issues.apache.org/jira/browse/HBASE6121 is > > > > > > > > complaining about the exact same issue, but was never > > > > > > > > resolved. > > > > > > > > > > > > > > > > > > > > > > > Which issue? > > > > > > > https://issues.apache.org/jira/browse/HBASE-6121 > > > > > > > seems unrelated. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > The heartbeat JIRA in 13090 protect for situation where > > > > > > > > server scanner takes so long to retrieve the highly > > > > > > > > filtered information, that it exceeds the RPC timeout > > > > > > > > (hbase.rpc.timeout). > > > > > > > > > > > > > > > > > > > > > > > > > > > > > The timeout we are experiencing is the > > > > > > > > hbase.client.scanner.timeout.period, > > > > > > > > also deprecatedly known as hbase.regionserver.lease.period > > > > > > > > The mechanism is different: here, region server scanners > > > > > > > > wants to protect themselves against dead clients that > > > > > > > > would not perform "close", and allow releasing server side > > > > > > > > scanner resources. To do that, a lease mechanism is > > > > > > > > implemented, and if between 2 > > > > > > > > next() call, more than hbase.regionserver.lease.period > > > > > > > > occurs, the server side scanner will have been forced > > > > > > > > closed by this lease timeout safety mechanism. On late > > > > > > > > next() call, client will receive a DNRIOE of type > > > > > > > > unknownScannerException, and the client will assess that > > > > > > > > it is coming most likely from the lease timeout (and not > > > > > > > > from a region move), therefore throwing an exception > > > > > > > > instead of reset scanner (for the region move scenario). > > > > > > > > > > > > > > > > Hbase 1.1 does not address, as far as I have researched, > > > > > > > > the hbase.client.scanner.timeout.period issue we are facing. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Can you not have the high-level query that is being fed by a > > > > > > > scan do HBASE-13333? That is, tickle, the ongoing scan on > > > > > > > occasion just to say that I'm still alive? > > > > > > > > > > > > > > Otherwise, what would you suggest? A scan that does not > timeout? > > > > > > > Or the client being able to set a timeout in the Scan passed > > > > > > > to the > > > > > server? > > > > > > > > > > > > > > Sorry for late reply, > > > > > > > St.Ack > > > > > > > > > > > > > > > > > > > > > > > > > > > > > And yes, we will move to Hbase 1.1, and 1.0 as Cloudera > > > > > > > > and Hortonworks are having version mismatch on the next > > > > > > > > official builds trafodion will support. > > > > > > > > > > > > > > > > So my question is still open? > > > > > > > > > > > > > > > > Best regards, > > > > > > > > Eric Owhadi > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -----Original Message----- > > > > > > > > From: saint....@gmail.com [mailto:saint....@gmail.com] On > > > > > > > > Behalf Of Stack > > > > > > > > Sent: Monday, August 24, 2015 11:07 PM > > > > > > > > To: HBase Dev List > > > > > > > > Subject: Re: Question on > > > > > > > > hbase.client.scanner.timeout.period > > > > > > > > > > > > > > > > On Mon, Aug 24, 2015 at 4:48 PM, Eric Owhadi > > > > > > > > <eric.owh...@esgyn.com> > > > > > > > > wrote: > > > > > > > > > > > > > > > > > Hello everyone, > > > > > > > > > We have been facing a situation on trafodion, where we > > > > > > > > > are hitting the hbase.client.scanner.timeout.period > > > > > > > > > scenario: > > > > > > > > > basically, when doing queries that require spilling to > > > > > > > > > disk because of high complexity of what is involved, the > > > > > > > > > underlying hbase scanner serving one of the operation > > > > > > > > > involved in the complex query cannot call the next() > > > > > > > > > withing the timeout specify... too busy taking care of > > > > > > > > > other business. > > > > > > > > > This is legit scenario, and I was wondering why in the > > > > > > > > > code, special care is done to make sure that client > > > > > > > > > side, if a DNRIOE of type unknownScannerException shows > > > > > > > > > up, and the hbase.client.scanner.timeout.period time > > > > > > > > > elapsed, we make sure to throw a > > > > > > > > > scannerTimeoutException, instead of just let it go and > reset > > > > > > > > > scanner. > > > > > > > > > > > > > > > > > > Scanners were redone in hbase 1.1. Can Trafodion come up > > > > > > > > > onto hbase > > > > > > > 1.1? > > > > > > > > See > > > > > > > > https://blogs.apache.org/hbase/entry/scan_improvements_in_ > > > > > > > > hb > > > > > > > > as > > > > > > > > e_1 > > > > > > > > for summary. > > > > > > > > St.Ack > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I imagine that the lease time out implementation on > > > > > > > > > region server side is supposed to protect from resource > > > > > > > > > leak of scanner object server side. But I am not sure > > > > > > > > > why we would make it so that client side throw this > > > > > > > > > timeout exception, when in fact what just happened was > > > > > > > > > that client was too busy to call next() on > > > > time. > > > > > > > > > > > > > > > > > > I am sure there is a reason, but cannot figure it out :-). > > > > > > > > > > > > > > > > > > BTW, I found this JIRA, talking about exact same thing: > > > > > > > > > https://issues.apache.org/jira/browse/HBASE61-21 but > > > > > > > > > with no > > > > > > > resolution. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Any help understanding the reason of the timeout thrwown > > > > > > > > > client side instead of an automatic reset would be much > > > > > > > > > appreciated, Best regards, Eric Owhadi > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
