Hi Matt,
You StringOne is clearly not null else it would have thrown an
exception in the if. You should not be calling equals on String unless you are
sure that it is not null; use == instead for nullity checks. This means that
one of 'kvbuffer' or 'b' (byte[] argument) to be null.
Mind telling us the hadoop version you are using?
Any chance that there are two or more threads in your mapper class?
Regards,
Anand
On 04-Jul-2012, at 2:46 AM, Berry, Matt wrote:
> While emitting a record from my mapper, I am receiving a
> NullPointerException. The stack trace seems to indicate there is a problem
> serializing the Key. The key contains a few strings and a few longs. It is a
> string that it is having trouble serializing. I've checked the contents of
> the string post-mortem and it looks like a valid string (at least, other
> strings like it work just fine). Could this be a problem not with the string
> itself but the destination of the arraycopy()?
>
> The Key.write(DataOutput out) function:
>
> @Override
> public void write(DataOutput out) throws IOException {
> if(StringOne.equals(null) | StringTwo.equals(null)) {
> System.out.println("This is not hit");
> }
> out.writeUTF(StringOne); //Line 125
> out.writeUTF(StringTwo);
> out.writeLong(LongOne);
> out.writeLong(LongTwo);
> }
>
>
> The Stack Trace:
>
> java.lang.NullPointerException
> at java.lang.System.arraycopy(Native Method)
> at
> org.apache.hadoop.mapred.MapTask$MapOutputBuffer$Buffer.write(MapTask.java:1108)
> at java.io.DataOutputStream.write(DataOutputStream.java:90)
> at java.io.DataOutputStream.writeUTF(DataOutputStream.java:384)
> at java.io.DataOutputStream.writeUTF(DataOutputStream.java:306)
> at xxxxxx.xxxxxxxxxxxx.xxxx.xxxxx.xxxxxKey.write(xxxxxKey.java:125)
> at
> org.apache.hadoop.io.serializer.WritableSerialization$WritableSerializer.serialize(WritableSerialization.java:90)
> at
> org.apache.hadoop.io.serializer.WritableSerialization$WritableSerializer.serialize(WritableSerialization.java:77)
> at
> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:892)
> at
> org.apache.hadoop.mapred.MapTask$NewOutputCollector.write(MapTask.java:541)
> at
> org.apache.hadoop.mapreduce.TaskInputOutputContext.write(TaskInputOutputContext.java:80)
> at
> xxxxxx.xxxxxxxxxxx.xxxx.xxxxxxxx.xxx.xxxxxxxxxxxxxxxxxxxxxxx.map(xxxxxxxxxxxxxxxxxMapper.java:82)
> at
> xxxxxx.xxxxxxxxxxx.xxxx.xxxxxxxx.xxx.xxxxxxxxxxxxxxxxxxxxxxx.map(xxxxxxxxxxxxxxxxxMapper.java:63)
> at
> xxxxxx.xxxxxxxxxxx.xxxx.xxxxxxx.xxxxxxxxxxxxxxxxxxxxxxxxxxxx.xxxxxxxxxx(xxxxxxxxxxxxxxxxxxxxxxxxxxxx.java:131)
> at
> xxxxxx.xxxxxxxxxxx.xxxx.xxxxx.xxxxxxxxxxxxxx.xxxxxxxxxxxxxxx(xxxxxxxxxxxxxx.java:282)
> at
> xxxxxx.xxxxxxxxxxx.xxxx.xxxxx.xxxxxxxxxxxxxx.access$000(xxxxxxxxxxxxxx.java:42)
> at
> xxxxxx.xxxxxxxxxxx.xxxx.xxxxx.xxxxxxxxxxxxxx$xxxxxxxxxxxx.run(xxxxxxxxxxxxx.java:74)
> at
> java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
> at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
> at java.util.concurrent.FutureTask.run(FutureTask.java:138)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
> at java.lang.Thread.run(Thread.java:662)
