HADOOP-11418:Property "io.compression.codec.lzo.class" does not work with other value besides default

[lulynn_2008]

Hi All,

Could I try other codec besides lzo using hadoop-common TFile property 
"io.compression.codec.lzo.class"? If not, please ignore following information.

I was trying "io.compression.codec.lzo.class" with value 
"com.ibm.biginsights.compress.CmxCodec" (not the default 
"org.apache.hadoop.io.compress.LzoCodec"). The jar for this CmxCodec is called 
ibm-compression.jar. But I always encountered following errors:
"java.io.IOException: LZO codec class not specified. Did you forget to set 
property io.compression.codec.lzo.class?"

I lunched mapreduce jobs and from "job*.xml" I could find this property was set 
correctly. And also could find ibm-compression.jar in "java.class.path".
From following code, seems "io.compression.codec.lzo.class" does not work for 
other codec besides default. Hadoop will always treat it as defaultClazz. I 
think it is a bug and opened this jira. Please help give a glance and give your 
comments. Thanks

     77       private static final String defaultClazz =
     78           "org.apache.hadoop.io.compress.LzoCodec";

     82       public synchronized boolean isSupported() {
     83         if (!checked) {
     84           checked = true;
     85           String extClazz =
     86               (conf.get(CONF_LZO_CLASS) == null ? System
     87                   .getProperty(CONF_LZO_CLASS) : null);
     88           String clazz = (extClazz != null) ? extClazz : defaultClazz;