Yes. On the maxRetries, though ... I saw the code (http://grepcode.com/file/repo1.maven.org/maven2/org.apache.hbase/hbase/0.90.2/org/apache/hadoop/hbase/ipc/HBaseClient.java#677) show this.maxRetries = conf.getInt("hbase.ipc.client.connect.max.retries", 0);
So - looks like by default, the maxRetries is set to 0? So ... there is effectively no retry (i.e. it is fail-fast) --Suraj On Tue, Jul 10, 2012 at 10:12 AM, N Keywal <nkey...@gmail.com> wrote: > Thanks for the jira. > The client can be connected to multiple RS, depending on the rows is > working on. So yes it's initial, but it's a dynamic initial :-). > This said there is a retry on error... > > On Tue, Jul 10, 2012 at 6:46 PM, 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
