cloudera impalad服务调试问题

    首先，在此真的要感谢Google impala-user的各位大牛不吝时间为我指点迷津。闲话不说，刚接触impala不久，前段时间一直在看其源码，随后就是调试工作的展开，刚一开始就出现了问题。在编译通过后的源码之上进行调试工作，由于整个项目是用cmake管理的，直接在编译阶段有生成可debug的可执行程序，具体在${IMPALA_HOME}/be/build/debug这个目录下，所以调试可以由以下几步完成：

    1）启动impalad

    2）使用gdb attach pidofimpalad进入调试环境

    3）在另一个终端shell下运行impala-shell.sh脚本

    但按照gdb调试的过程进行时，shell端连接上impalad之后，在执行sql query查询语句的时候，在调试端出现以下错误：

[impala@hadoop-01 service]$ gdb -q impalad 
Reading symbols from /usr/local/src/impala/be/build/debug/service/impalad...done.
(gdb) set args -use_statestore=false -nn=hadoop-01.localdomain -nn_port=8030
(gdb) b main
Breakpoint 1 at 0x9adba1: file /usr/local/src/impala/be/src/service/impalad-main.cc, line 71.
(gdb) r
Starting program: /usr/local/src/impala/be/build/debug/service/impalad -use_statestore=false -nn=hadoop-01.localdomain -nn_port=8030
[Thread debugging using libthread_db enabled]

Breakpoint 1, main (argc=4, argv=0x7fffffffbc48) at /usr/local/src/impala/be/src/service/impalad-main.cc:71
71	  InitDaemon(argc, argv);
Missing separate debuginfos, use: debuginfo-install boost-date-time-1.41.0-11.el6_1.2.x86_64 boost-regex-1.41.0-11.el6_1.2.x86_64 boost-thread-1.41.0-11.el6_1.2.x86_64 bzip2-libs-1.0.5-7.el6_0.x86_64 glibc-2.12-1.80.el6_3.6.x86_64 libevent-1.4.13-4.el6.x86_64 libgcc-4.4.6-4.el6.x86_64 libicu-4.2.1-9.1.el6_2.x86_64 libstdc++-4.4.6-4.el6.x86_64 zlib-1.2.3-27.el6.x86_64
(gdb) n
73	  LlvmCodeGen::InitializeLlvm();
(gdb) n
76	  if (!FLAGS_principal.empty()) {
(gdb) c
Continuing.
[New Thread 0x7ffff2dd8700 (LWP 7856)]
[New Thread 0x7ffff2cd7700 (LWP 7857)]
[New Thread 0x7ffff2a3a700 (LWP 7858)]
[New Thread 0x7ffff2939700 (LWP 7859)]
[New Thread 0x7ffff2838700 (LWP 7860)]
[New Thread 0x7fffec8a6700 (LWP 7861)]
[New Thread 0x7fffec7a5700 (LWP 7862)]
[New Thread 0x7fffec6a4700 (LWP 7863)]
[New Thread 0x7fffec5a3700 (LWP 7864)]
[New Thread 0x7fffec4a2700 (LWP 7865)]

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff3277068 in ?? ()
(gdb) l
71	  InitDaemon(argc, argv);
72	
73	  LlvmCodeGen::InitializeLlvm();
74	  
75	  // Enable Kerberos security if requested.
76	  if (!FLAGS_principal.empty()) {
77	    EXIT_IF_ERROR(InitKerberos("Impalad"));
78	  }
79	  
80	  JniUtil::InitLibhdfs();
(gdb) c
Continuing.

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff6e72f2e in InterpreterRuntime::newarray(JavaThread*, BasicType, int) () from /usr/java/default/jre/lib/amd64/server/libjvm.so
(gdb) c
Continuing.
[New Thread 0x7fffebc5d700 (LWP 7874)]
[New Thread 0x7fffeba45700 (LWP 7875)]
[New Thread 0x7fffeb044700 (LWP 7876)]
13/01/28 09:44:17 WARN conf.HiveConf: DEPRECATED: Ignoring hive-default.xml found on the CLASSPATH at /usr/local/src/impala/fe/src/test/resources/hive-default.xml
13/01/28 09:44:18 WARN conf.Configuration: mapred.max.split.size is deprecated. Instead, use mapreduce.input.fileinputformat.split.maxsize
13/01/28 09:44:18 WARN conf.Configuration: mapred.min.split.size is deprecated. Instead, use mapreduce.input.fileinputformat.split.minsize
13/01/28 09:44:18 WARN conf.Configuration: mapred.min.split.size.per.rack is deprecated. Instead, use mapreduce.input.fileinputformat.split.minsize.per.rack
13/01/28 09:44:18 WARN conf.Configuration: mapred.min.split.size.per.node is deprecated. Instead, use mapreduce.input.fileinputformat.split.minsize.per.node
13/01/28 09:44:18 WARN conf.Configuration: mapred.reduce.tasks is deprecated. Instead, use mapreduce.job.reduces
13/01/28 09:44:18 WARN conf.Configuration: mapred.reduce.tasks.speculative.execution is deprecated. Instead, use mapreduce.reduce.speculative

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffec7a5700 (LWP 7862)]
0x00007ffff6ce74e3 in ciMethod::method_data() () from /usr/java/default/jre/lib/amd64/server/libjvm.so

     其实错误很明显，就是libjvm.so动态共享库在调试接受shell端query请求时，发生了SIGSEGV引发的段错误，当时一头雾水，以为是jdk的问题，后来通过在谷歌讨论组的提问，得到了解决的方法，现将解决方法分享给那些和我遇到相同问题的大家：

    用gdb调试impala be的时候，JVM会产生大量的段错误，这里就需要我们手动告诉gdb去忽略他们或者让java处理它们，这里只需要在执行run之前，添加一行命令：

gdb> handle SIGSEGV nostop noprint pass

     这样就可以避免遇到各种Segmentation faults这样的问题而导致shell端查询一直没有结果返回。

     再次，感谢那些分享自己经验的大牛，向你们致敬！