I got this error today.
INFO 11:16:08,067 Enqueuing flush of Memtable-LocationInfo@8820986(41/51 serialized/live bytes, 1 ops)
 INFO 11:16:08,068 Writing Memtable-LocationInfo@8820986(41/51 serialized/live bytes, 1 ops)
ERROR 11:16:08,077 Exception in thread Thread[COMMIT-LOG-ALLOCATOR,5,main]
java.io.IOError: java.io.IOException: Map failed
at org.apache.cassandra.db.commitlog.CommitLogSegment.<init>(CommitLogSegment.java:127)
at org.apache.cassandra.db.commitlog.CommitLogAllocator$3.run(CommitLogAllocator.java:203)
at org.apache.cassandra.db.commitlog.CommitLogAllocator$1.runMayThrow(CommitLogAllocator.java:95)
at org.apache.cassandra.utils.WrappedRunnable.run(WrappedRunnable.java:30)
at java.lang.Thread.run(Thread.java:679)
Caused by: java.io.IOException: Map failed
at sun.nio.ch.FileChannelImpl.map(FileChannelImpl.java:803)
at org.apache.cassandra.db.commitlog.CommitLogSegment.<init>(CommitLogSegment.java:119)
... 4 more
Caused by: java.lang.OutOfMemoryError: Map failed
at sun.nio.ch.FileChannelImpl.map0(Native Method)
at sun.nio.ch.FileChannelImpl.map(FileChannelImpl.java:800)
... 5 more
ERROR 11:16:08,082 Exception in thread Thread[StorageServiceShutdownHook,5,main]
java.lang.NullPointerException
at org.apache.cassandra.gms.Gossiper.stop(Gossiper.java:1132)
at org.apache.cassandra.service.StorageService$2.runMayThrow(StorageService.java:489)
at org.apache.cassandra.utils.WrappedRunnable.run(WrappedRunnable.java:30)
at java.lang.Thread.run(Thread.java:679)


Are the two issues related?

On Mon, May 27, 2013 at 1:50 PM, Kais Ahmed <kais@neteck-fr.com> wrote:
Hi chiddu,

You have to configure your operating system to use the Oracle JRE instead of OpenJDK.

http://www.datastax.com/docs/1.0/install/install_jre



2013/5/27 S Chidambaran <chiddu@gmail.com>
I get these errors frequently as Cassandra starts up. I'm using the official Java distribution from Ubuntu.


WARN 08:11:48,145 MemoryMeter uninitialized (jamm not specified as java agent); assuming liveRatio of 10.0.  Usually this means cassandra-env.sh disabled jamm because you are using a buggy JRE; upgrade to the Sun JRE instead



java version "1.6.0_27"
OpenJDK Runtime Environment (IcedTea6 1.12.5) (6b27-1.12.5-0ubuntu0.12.04.1)
OpenJDK Server VM (build 20.0-b12, mixed mode)


Any idea on how to fix this?

Regards
Chiddu