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From stack <st...@duboce.net>
Subject Re: HBaseAdmin and ConcurrentModificationException
Date Fri, 15 Jan 2010 23:33:50 GMT
Don't make changes to the Configuration in your JVM after its been shared
amongst threads?  Configuration is not thread safe.  It'd be tough making it
thread-safe.  It comes from hadoop-common.
St.Ack

On Fri, Jan 15, 2010 at 11:14 AM, Ted Yu <yuzhihong@gmail.com> wrote:

> Here is the stack:
> INFO   | jvm 1    | 2010/01/14 16:03:11 |
> java.util.ConcurrentModificationException
> INFO   | jvm 1    | 2010/01/14 16:03:11 |       at
> java.util.AbstractList$Itr.checkForComodification(Unknown Source)
> INFO   | jvm 1    | 2010/01/14 16:03:11 |       at
> java.util.AbstractList$Itr.next(Unknown Source)
> INFO   | jvm 1    | 2010/01/14 16:03:11 |       at
> org.apache.hadoop.conf.Configuration.loadResources(Configuration.java:1028)
> INFO   | jvm 1    | 2010/01/14 16:03:11 |       at
> org.apache.hadoop.conf.Configuration.getProps(Configuration.java:979)
> INFO   | jvm 1    | 2010/01/14 16:03:11 |       at
> org.apache.hadoop.conf.Configuration.get(Configuration.java:435)
> INFO   | jvm 1    | 2010/01/14 16:03:11 |       at
> org.apache.hadoop.hbase.client.HConnectionManager
> $TableServers.<init>(HConnectionManager.java:257)
> INFO   | jvm 1    | 2010/01/14 16:03:11 |       at
>
> org.apache.hadoop.hbase.client.HConnectionManager.getConnection(HConnectionManager.java:99)
> INFO   | jvm 1    | 2010/01/14 16:03:11 |       at
> org.apache.hadoop.hbase.client.HBaseAdmin.<init>(HBaseAdmin.java:68)
>
> This line in HConnectionManager caused the exception:
>      String serverClassName =
>        conf.get(REGION_SERVER_CLASS, DEFAULT_REGION_SERVER_CLASS);
>
> Strangely, reading config file threw ConcurrentModificationException:
> "Z:\kindsight\hbase\software\conf\hbase-default.xml"(117,11):
> <name>hbase.regionserver.class</name>
>
> Please advise.
>
> On Fri, Jan 15, 2010 at 10:28 AM, stack <stack@duboce.net> wrote:
>
> > You have multiple instances of HBaseAdmin floating around?   If so, why?
> >  Please paste full stack trace.  That'd help.
> > Yours,
> > St.Ack
> >
> > On Fri, Jan 15, 2010 at 10:22 AM, Ted Yu <yuzhihong@gmail.com> wrote:
> >
> > > Hi,
> > > We use hbase-0.20.1
> > > I have seen this randomly fail with a ConcurrentModificationException:
> > >      HBaseAdmin admin = new HBaseAdmin(hbaseConf);
> > >
> > > Has anybody else seen this behavior ?
> > >
> > > Thanks
> > >
> >
>

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