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From Andrew Purtell <apurt...@apache.org>
Subject Re: Region servers going down frequently (0.20 alpha)
Date Mon, 29 Jun 2009 17:26:03 GMT
Hi,

I suspect your cluster is too small for what you are trying to do
with it. This is why I first suggested setting up a stable ZK ensemble,
as this would be one of the first components to be affected by out of
tolerance latencies due to swapping. 

How much RAM do these nodes have? How much heap are you allocating to
each JVM? (Have you made changes to the -Xmx settings in the launcher
script?) Do you have host level metrics running? If not, consider
watching this with Ganglia, or, in this case, since the cluster is so
small three terminals running top or atop. After 20, 30 minutes, is
all available RAM full and are the nodes going in to swap?

I have been debating if an all RAM system is best for Hadoop and HBase
installations. Because the latency of the JVM GC cycle will spike out
of tolerance if the heap goes into swap, running without swap keeps
everyone honest. For example, a node running the following services:

   datanode (1 GB heap)
   region server (2 GB heap)
   task tracker (1 GB heap)
   map / reduce tasks (200 MB heap each is the default) x 4

and ~1 GB for kernel and system daemons can run within 8 GB of RAM. 

If your tables are going to be really large (or why else use Bigtable?)
and the workload can benefit from caching, up the RAM and allocate more
heap to the region servers for cache. 

   - Andy



On Mon, Jun 29, 2009 at 8:51 AM, Murali Krishna. P
<muralikpbhat@yahoo.com>wrote:

> Hi,
>  Just want to send the latest update...With 3 ZK peers, it was much more
> stable. The entire setup ran fine for more than 4 hours. But got the same
> problem after that and one of the region server was shutdown. Looks like
> zookeeper expire event and the RS restart is failing..
>
> Master log:
> 2009-06-29 08:18:31,100 INFO org.apache.hadoop.hbase.master.ServerManager:
> 3 region servers, 0 dead, average load 2.0
> 2009-06-29 08:18:34,544 INFO org.apache.hadoop.hbase.master.ServerManager:
> RSHOST,60020,1246272222149 znode expir
> ed
> 2009-06-29 08:18:34,797 INFO
> org.apache.hadoop.hbase.master.RegionServerOperation: process shutdown of
> server scrub02.image.search.re4.yahoo.
> com,60020,1246272222149: logSplit: false, rootRescanned: false,
> numberOfMetaRegions: 1, onlineMetaRegions.size(): 1
>
> RS log:
> 2009-06-29 08:19:15,731 WARN org.apache.hadoop.hbase.util.Sleeper: We slept
> 60203ms, ten times longer than scheduled: 3000
> 2009-06-29 08:19:15,955 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer: Got ZooKeeper event,
> state: Disconnected, type: None, path:
> null
> 2009-06-29 08:19:16,029 WARN
> org.apache.hadoop.hbase.regionserver.HRegionServer: Processing message
> (Retry: 0)
> org.apache.hadoop.hbase.Leases$LeaseStillHeldException
>
>
> May be the machine goes busy and the zookeeper has issues with that, but it
> is surprising why the region server is not able to recover. Any clue?
>
> Thanks,
> Murali Krishna
>
>
>
>
> ________________________________
> From: Andrew Purtell <apurtell@apache.org>
> To: hbase-user@hadoop.apache.org
> Sent: Monday, 29 June, 2009 12:14:57 PM
> Subject: Re: Region servers going down frequently (0.20 alpha)
>
> Hi,
>
> Configuring 'myid' files are part of the Zookeeper set up process.
> Are you aware of the instructions for how to set up Zookeeper here:
>
>  http://hadoop.apache.org/zookeeper/docs/current/zookeeperAdmin.html
>
> ?
>
> From:
>
>
> http://hadoop.apache.org/zookeeper/docs/current/zookeeperAdmin.html#sc_zkMulitServerSetup
>
> "For reliable ZooKeeper service, you should deploy ZooKeeper in a cluster
> known as an ensemble. [...] Here are the steps to setting a server that will
> be part of an ensemble. These steps should be performed on every host in the
> ensemble: ..."
>
>    - Andy
>
>
>
>
> ________________________________
> From: Murali Krishna. P <muralikpbhat@yahoo.com>
> To: hbase-user@hadoop.apache.org
> Sent: Sunday, June 28, 2009 10:12:02 PM
> Subject: Re: Region servers going down frequently (0.20 alpha)
>
> Hi Andrew,
> Thanks for looking into this.
> I tried adding 3 nodes to the zoo.cfg but it threw an erros saying 'myid'
> file is missing. Now even if i go back to my old config, it still throws the
> error :(
>
> Thanks,
> Murali Krishna
>
>
>
>
> ________________________________
> From: Andrew Purtell <apurtell@apache.org>
> To: hbase-user@hadoop.apache.org
> Sent: Sunday, 28 June, 2009 10:47:12 PM
> Subject: Re: Region servers going down frequently (0.20 alpha)
>
> Hello,
>
> As a first step, deploy Zookeeper quorum peers on all of your nodes and
> list all peers in the zoo.cfg files of your Zookeeper install and HBase:
>
>  server.1=node1:2888:3888
>  server.2=node2:2888:3888
>  server.3=node3:2888:3888
>
> Are you running mapreduce tasks as well as otherwise what you have
> described
> below?
>
> Do you see any messages in the master or region server logs along the lines
> of "we slept for NNNNNNms, wanted NNNNms"? How much RAM do these nodes
> have?
> Do you have host level metrics running? If not, consider watching this with
> Ganglia, or, in this case, since the cluster is so small three terminals
> running top or atop. After 20, 30 minutes, is all available RAM full and
> are
> the nodes going in to swap?
>
>   - Andy
>
>
>
>
> ________________________________
> From: Murali Krishna. P <muralikpbhat@yahoo.com>
> To: hbase-user@hadoop.apache.org
> Sent: Sunday, June 28, 2009 8:23:27 AM
> Subject: Region servers going down frequently (0.20 alpha)
>
> Hi,
>  I am repeatedly running into this issue where all the region servers tries
> to restart but fails to come up. All the region servers seems to be having
> same kind of exception which causes this state.
>
> My cluster is as follows:
> node1 : Master, NN, DN, RS, TT, XX
> node2: Zookeeper, JT, DN, RS, TT, XX
> node3: DN, RS, TT, XX
>
> where  XX is my own hbase client with around 150 threads writing to a
> common table.
>
> The setup works fine for some time and then goes down (after 20, 30 mins).
> Here is the sequence in the region server logs..
>
>    * RS gets a zookeeper event : Got ZooKeeper event, state: Disconnected,
> type: None, path:
> null
>    * RS retries 'processing image', gets LeaseStillHeldE: 2009-06-28
> 02:14:17,013 WARN org.apache.hadoop.hbase.regionserver.HRegionServer:
> Processing message (Retry: 1)
> org.apache.hadoop.hbase.Leases$LeaseStillHeldException
>    * After 10 retries, gets another zoookeeper event : Got ZooKeeper event,
> state: Expired, type: None, path: null
> 2009-06-28 02:14:17,751 ERROR
> org..apache.hadoop.hbase.regionserver.HRegionServer: ZooKeeper session
> expired
> 2009-06-28 02:14:17,751 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer: Restarting Region Server
>    * Decides to restart region server, but logs of error like this:
> 2009-06-28 02:14:17,997 INFO org.apache.hadoop.ipc.HBaseServer: IPC Server
> handler 280 on 60020, call exists([B@75880048,
> row=724b330295375ad0ba68fa85325381, maxVersions=1,
> timeRange=[0,9223372036854775807), families=ALL) from 69.147.127.248:48945:
> error: java.io.IOException: Ser
> ver not running, aborting
>    * Above might be happening because client 'XX' still trying to write?
> Finally it closes the region server and tries to restart. But gets the
> following exception:2009-06-28 02:14:26,462 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer: Starting shutdown
> thread.
> 2009-06-28 02:14:26,462 INFO
> org.apache.hadoop.hbase..regionserver.HRegionServer: Runs every 10000000ms
> 2009-06-28 02:14:26,462 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer: Shutdown thread complete
> 2009-06-28 02:14:27,032 ERROR
> org.apache.hadoop.hbase.regionserver.HRegionServer: Failed init
> java.lang.NullPointerException
>        at
> org.apache.hadoop.hbase.regionserver.HRegionServer.init(HRegionServer.java:713)
>        at
> org.apache.hadoop.hbase.regionserver.HRegionServer.run(HRegionServer..java:431)
>        at java.lang.Thread.run(Thread.java:619)
> 2009-06-28 02:14:27,110 FATAL
> org.apache.hadoop.hbase.regionserver.HRegionServer: Unhandled exception.
> Aborting...
> java.io.IOException: Region server startup failed
>        at
> org.apache.hadoop.hbase.regionserver.HRegionServer.convertThrowableToIOE(HRegionServer.java:832)
>        at
> org.apache.hadoop.hbase.regionserver.HRegionServer.init(HRegionServer.java:751)
>        at
> org..apache.hadoop.hbase.regionserver.HRegionServer.run(HRegionServer.java:431)
>        at java.lang.Thread.run(Thread.java:619)
> Caused by: java.lang.NullPointerException
>        at
> org.apache.hadoop.hbase.regionserver.HRegionServer.init(HRegionServer.java:713)
>        ... 2 more
> 2009-06-28 02:14:27,122 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer: Dump of metrics:
> request=0.0, regions=9, stores=10, storefil
> es=20, storefileIndexSize=0, memcacheSize=52, usedHeap=170, maxHeap=1995,
> blockCacheSize=49971560, blockCacheFree=28440, blockCacheCount=765,
> blockCacheHitRatio=94
> 2009-06-28 02:14:27,131 INFO org.apache.hadoop.ipc.HBaseServer: Stopping
> server on 60020
> 2009-06-28 02:14:27,131 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer: Stopping infoServer
> 2009-06-28 02:14:27,131 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer: On abort, closed hlog
> 2009-06-28 02:14:27,136 INFO
> org.apache.hadoop.hbase...regionserver.HRegionServer: aborting server at:
> 0.0.0.0:60020
>
> There region server dies after that. All the 3 region servers die like this
> and I have to start the region server manually. But aftert 10-15 minutes, it
> runs into the same stage again. Please help me in finding what is the root
> cause of this?
>
> Thanks,
> Murali Krishna
> /
>



      
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