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_hbase_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 > > >
