FYI, below I quoted the customers' response after I explained the NULLException
is caused by the row lock. So my question is if this is allowed situation for
multiple threads/process to compete for the lock, the one who did not get
should be considered normal and not throwing NullPointerException?
Thanks
Tian-Ying
Quote from customer below:
"Well yes, not only multiple threads, but multiple processes!
That’s why we need a lock.
Although I do see some practical problems, and am trying to NOT do the same
lock from multiple threads within the same process, but it is needed to
coordinate locks across processes"
________________________________________
From: ramkrishna vasudevan [ramkrishna.s.vasude...@gmail.com]
Sent: Thursday, May 16, 2013 10:16 AM
To: user@hbase.apache.org
Subject: Re: NullPointerException while loading large amount of new rows into
HBase, exception is thrown when trying to obtain lock for RowKey
Which version of HBase?
Regards
Ram
On Thu, May 16, 2013 at 10:42 PM, Tianying Chang <tich...@ebaysf.com> wrote:
> Hi,
>
> When our customers(using TSDB) loads large amount of data into HBase, we
> saw many NullPointerException in the RS logs as below. I checked the source
> code, it seems when trying to obtain the lock for a rowKey, if the entry
> for that row already exists and the "waitfoBlock" is false (therefore it
> won't retry, but just return a NULL value). I can see in
> doMiniBatchMutation(), the waitForBlock is set to be false. (most other
> places "waitForBlock" is always set to true).
>
> This exception is thrown from function lockRow(), which has been
> deprecated. I am not sure why it is deprecated, and what is used to replace
> it. Is this normal? which implies the HBase should not throw this
> misleading error message to log. Or should the client call some other API?
>
> Thanks
> Tian-Ying
>
> 2013-05-14 12:45:30,911 DEBUG
> org.apache.hadoop.hbase.regionserver.HRegionServer: Row lock
> -3430274391270203797 explicitly acquired by client
> 2013-05-14 12:45:30,911 WARN org.apache.hadoop.ipc.HBaseServer:
> (responseTooSlow): {"processingtimems":29783,"call":"lockRow([B@339a6a5c,
> [B@5ebcd87b), rpc version=1, client version=29,
> methodsFingerPrint=0","client":"10.53.106.37:58892
> ","starttimems":1368560701128,"queuetimems":847,"class":"HRegionServer","responsesize":0,"method":"lockRow"}
> 2013-05-14 12:46:00,911 ERROR
> org.apache.hadoop.hbase.regionserver.HRegionServer: Error obtaining row
> lock (fsOk: true)
> java.lang.NullPointerException
> at
> java.util.concurrent.ConcurrentHashMap.put(ConcurrentHashMap.java:881)
> at
> org.apache.hadoop.hbase.regionserver.HRegionServer.addRowLock(HRegionServer.java:2346)
> at
> org.apache.hadoop.hbase.regionserver.HRegionServer.lockRow(HRegionServer.java:2332)
> at sun.reflect.GeneratedMethodAccessor156.invoke(Unknown
> Source)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> at java.lang.reflect.Method.invoke(Method.java:597)
> at
> org.apache.hadoop.hbase.ipc.WritableRpcEngine$Server.call(WritableRpcEngine.java:384)
> at
> org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:1336)
> 2013-05-14 12:46:02,514 WARN org.apache.hadoop.ipc.HBaseServer: IPC Server
> Responder, call get([B@2166c821,
> {"timeRange":[0,9223372036854775807],"totalColumns":1,"cacheBlocks":true,"families":{"id":["tagv"]},"maxVersions":1,"row":"
> slcsn-s00314.slc.ebay.com"}), rpc version=1, client version=29,
> methodsFingerPrint=0 from 10.53.106.37:58892: output error
> 2013-05-14 12:46:02,514 WARN org.apache.hadoop.ipc.HBaseServer: IPC Server
> handler 3 on 60020 caught: java.io.IOException: Connection reset by peer
> at sun.nio.ch.FileDispatcher.write0(Native Method)
> at
> sun.nio.ch.SocketDispatcher.write(SocketDispatcher.java:29)
>
