Created https://issues.apache.org/jira/browse/HBASE-6364 for this issue.
Thanks, --Suraj On Tue, Jul 10, 2012 at 9:46 AM, Suraj Varma <svarma...@gmail.com> wrote: > I will create a JIRA ticket ... > > The only side-effect I could think of is ... if a RS is having a GC of > a few seconds, any _new_ client trying to connect would get connect > failures. So ... the _initial_ connection to the RS is what would > suffer from a super-low setting of the ipc.socket.timeout. This was my > read of the code. > > So - was hoping to get a confirmation if this is the only side effect. > Again - this is on the client side - I wouldn't risk doing this on the > cluster side ... > --Suraj > > On Mon, Jul 9, 2012 at 9:44 AM, N Keywal <nkey...@gmail.com> wrote: >> Hi, >> >> What you're describing -the 35 minutes recovery time- seems to match >> the code. And it's a bug (still there on trunk). Could you please >> create a jira for it? If you have the logs it even better. >> >> Lowering the ipc.socket.timeout seems to be an acceptable partial >> workaround. Setting it to 10s seems ok to me. Lower than this... I >> don't know. >> >> N. >> >> >> On Mon, Jul 9, 2012 at 6:16 PM, Suraj Varma <svarma...@gmail.com> wrote: >>> Hello: >>> I'd like to get advice on the below strategy of decreasing the >>> "ipc.socket.timeout" configuration on the HBase Client side ... has >>> anyone tried this? Has anyone had any issues with configuring this >>> lower than the default 20s? >>> >>> Thanks, >>> --Suraj >>> >>> On Mon, Jul 2, 2012 at 5:51 PM, Suraj Varma <svarma...@gmail.com> wrote: >>>> By "power down" below, I mean powering down the host with the RS that >>>> holds the .META. table. (So - essentially, the host IP is unreachable >>>> and the RS/DN is gone.) >>>> >>>> Just wanted to clarify my below steps ... >>>> --S >>>> >>>> On Mon, Jul 2, 2012 at 5:36 PM, Suraj Varma <svarma...@gmail.com> wrote: >>>>> Hello: >>>>> We've been doing some failure scenario tests by powering down a .META. >>>>> holding region server host and while the HBase cluster itself recovers >>>>> and reassigns the META region and other regions (after we tweaked down >>>>> the default timeouts), our client apps using HBaseClient take a long >>>>> time to recover. >>>>> >>>>> hbase-0.90.6 / cdh3u4 / JDK 1.6.0_23 >>>>> >>>>> Process: >>>>> 1) Apply load via client app on HBase cluster for several minutes >>>>> 2) Power down the region server holding the .META. server >>>>> 3) Measure how long it takes for cluster to reassign META table and >>>>> for client threads to re-lookup and re-orient to the lesser cluster >>>>> (minus the RS and DN on that host). >>>>> >>>>> What we see: >>>>> 1) Client threads spike up to maxThread size ... and take over 35 mins >>>>> to recover (i.e. for the thread count to go back to normal) - no calls >>>>> are being serviced - they are all just backed up on a synchronized >>>>> method ... >>>>> >>>>> 2) Essentially, all the client app threads queue up behind the >>>>> HBaseClient.setupIOStreams method in oahh.ipc.HBaseClient >>>>> (http://grepcode.com/file/repo1.maven.org/maven2/org.apache.hbase/hbase/0.90.2/org/apache/hadoop/hbase/ipc/HBaseClient.java#312). >>>>> http://tinyurl.com/7js53dj >>>>> >>>>> After taking several thread dumps we found that the thread within this >>>>> synchronized method was blocked on >>>>> NetUtils.connect(this.socket, remoteId.getAddress(), >>>>> getSocketTimeout(conf)); >>>>> >>>>> Essentially, the thread which got the lock would try to connect to the >>>>> dead RS (till socket times out), retrying, and then the next thread >>>>> gets in and so forth. >>>>> >>>>> Solution tested: >>>>> ------------------- >>>>> So - the ipc.HBaseClient code shows ipc.socket.timeout default is 20s. >>>>> We dropped this down to a low number (1000 ms, 100 ms, etc) and the >>>>> recovery was much faster (in a couple of minutes). >>>>> >>>>> So - we're thinking of setting the HBase client side hbase-site.xml >>>>> with an ipc.socket.timeout of 100ms. Looking at the code, it appears >>>>> that this is only ever used during the initial "HConnection" setup via >>>>> the NetUtils.connect and should only ever be used when connectivity to >>>>> a region server is lost and needs to be re-established. i.e it does >>>>> not affect the normal "RPC" actiivity as this is just the connect >>>>> timeout. >>>>> >>>>> Am I reading the code right? Any thoughts on how whether this is too >>>>> low for comfort? (Our internal tests did not show any errors during >>>>> normal operation related to timeouts etc ... but, I just wanted to run >>>>> this by the experts.). >>>>> >>>>> Note that this above timeout tweak is only on the HBase client side. >>>>> Thanks, >>>>> --Suraj
