Unable to load native-hadoop library for your platform解决

环境：

Eclipse: eclipse-jee-indigo-SR1-linux-gtk.tar.gz

Hadoop: hadoop-0.20.203.0

1、在使用Hadoop的压缩输出流时，发现总是报这隔错误：

Unable to load native-hadoop library for your platform

找了很多资料，都没能解决，最后终于发现是自己将文件名多加了个空格，导致本地库路径错误。

实际的路径是：

/home/hadoop/hadoop-0.20.203.0/lib/native/Linux-i386-32

另外要注意的是，Eclipse 运行配置的VM变量要加上一句：

-Djava.library.path=/home/hadoop/hadoop-0.20.203.0/lib/native/Linux-i386-32

并在程序中输出该变量值，以保证设置正确：

		String libpath = System.getProperty("java.library.path");
		System.out.println("libpath=" + libpath);

2、如果用org.apache.hadoop.io.compress.DefaultCodec，则不需要lzo库，以免花费很多不必要的时间在编译安装lzo库上面，因为你可能根本用不着。

3、将日志设置为DEBUG级别，能获得更多的关于错误的信息。

	public static void main(String[] args) {		
		HdfsTest ht = new HdfsTest();
		String path = ht.getClass().getClassLoader().getResource("").getPath();
		System.out.println("path=" + path);
		
		String libpath = System.getProperty("java.library.path");
		System.out.println("libpath=" + libpath);
		
		PropertyConfigurator.configure(path + "log4j.properties");
                //do something
         }     

log4j.properties日志配置文件：

log4j.rootLogger=DEBUG,CONSOLE

log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.Threshold=DEBUG
log4j.appender.CONSOLE.Target=System.out
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%d - %c -%-4r [%t] %-5p %c %x - %m%n

4、可能需要编译本地库，在RedHat AS4 上不编译本地库会报错：

[hadoop@hdp0 hadoop-0.20.203.0]$ more hs_err_pid8895.log
#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGFPE (0x8) at pc=0x003d947c, pid=8895, tid=3074153392
#
# JRE version: 6.0_25-b06
# Java VM: Java HotSpot(TM) Server VM (20.0-b11 mixed mode linux-x86 )
# Problematic frame:
# C [ld-linux.so.2+0x847c]
#
# If you would like to submit a bug report, please visit:
# http://java.sun.com/webapps/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#

--------------- T H R E A D ---------------

Current thread (0x0805a000): JavaThread "main" [_thread_in_native, id=8921, sta
ck(0xb736d000,0xb73be000)]

siginfo:si_signo=SIGFPE: si_errno=0, si_code=1 (FPE_INTDIV), si_addr=0x003d947c

Registers:
EAX=0x0f4d007f, EBX=0x003e6fd4, ECX=0x00000000, EDX=0x00000000
ESP=0xb73bb02c, EBP=0xb73bb074, ESI=0x08304800, EDI=0x70984e4c
EIP=0x003d947c, EFLAGS=0x00010246, CR2=0x00000004

Top of Stack: (sp=0xb73bb02c)
0xb73bb02c: b73d7cce 70984619 b73bb0e8 b73bb000
0xb73bb03c: 00000000 00000000 00000000 70984e4c
0xb73bb04c: 70984618 70984218 00000007 08304b08
0xb73bb05c: 00000000 0f4d007f 70984619 003e6fd4
0xb73bb06c: 083049b0 70984619 b73bb148 003d9822
0xb73bb07c: 70984258 b73bb104 08304958 00000000
0xb73bb08c: 00000000 00000001 00000000 00000000
0xb73bb09c: 00511820 0000003c 003e6fd4 003e7650
. . .