java - 调用使用 libhdfs 的程序时出现 loadFileSystems 错误

Question

代码为libhdfs测试代码。

 int main(int argc, char **argv)
{
    hdfsFS fs = hdfsConnect("hdfs://labossrv14", 9000);
    const char* writePath = "/libhdfs_test.txt";
    hdfsFile writeFile = hdfsOpenFile(fs, writePath, O_WRONLY|O_CREAT, 0, 0, 0);
    if(!writeFile)
    {
        fprintf(stderr, "Failed to open %s for writing!\n", writePath);
        exit(-1);
    }
    char* buffer = "Hello, libhdfs!";
    tSize num_written_bytes = hdfsWrite(fs, writeFile, (void*)buffer, strlen(buffer)+1);
    if (hdfsFlush(fs, writeFile))
    {
        fprintf(stderr, "Failed to 'flush' %s\n", writePath);
        exit(-1);
    }
    hdfsCloseFile(fs, writeFile);
}

这段代码我费了很大功夫才编译成功，但是运行程序却不行。错误信息如下。

loadFileSystems error:
(unable to get stack trace for java.lang.NoClassDefFoundError exception: ExceptionUtils::getStackTrace error.)
hdfsBuilderConnect(forceNewInstance=0, nn=labossrv14, port=9000, kerbTicketCachePath=(NULL), userName=(NULL)) error:
(unable to get stack trace for java.lang.NoClassDefFoundError exception: ExceptionUtils::getStackTrace error.)
hdfsOpenFile(/libhdfs_test.txt): constructNewObjectOfPath error:
(unable to get stack trace for java.lang.NoClassDefFoundError exception: ExceptionUtils::getStackTrace error.)
Failed to open /libhdfs_test.txt for writing!

我根据 official document 玩这个东西.而且我发现问题可能是CLASSPATH不正确。下面是我的CLASSPATH，由“hadoop classpath --glob”生成的classpath和jdk、jre的lib路径组合而成。

export CLASSPATH=/home/junzhao/hadoop/hadoop-2.5.2/etc/hadoop:/home/junzhao/hadoop/hadoop-2.5.2/share/hadoop/common/lib/*:/home/junzhao/hadoop/hadoop-2.5.2/share/hadoop/common/*:/home/junzhao/hadoop/hadoop-2.5.2/share/hadoop/hdfs:/home/junzhao/hadoop/hadoop-2.5.2/share/hadoop/hdfs/lib/*:/home/junzhao/hadoop/hadoop-2.5.2/share/hadoop/hdfs/*:/home/junzhao/hadoop/hadoop-2.5.2/share/hadoop/yarn/lib/*:/home/junzhao/hadoop/hadoop-2.5.2/share/hadoop/yarn/*:/home/junzhao/hadoop/hadoop-2.5.2/share/hadoop/mapreduce/lib/*:/home/junzhao/hadoop/hadoop-2.5.2/share/hadoop/mapreduce/*:/contrib/capacity-scheduler/*.jar:/usr/lib/jvm/java-8-oracle/lib:/usr/lib/jvm/java-8-oracle/jre/lib:$CLASSPATH

有没有人有一些好的解决方案？谢谢!

Answer 1

又看了一遍教程中的一些资料和之前提出的一些问题。最后发现问题出在JNI没有对CLASSPATH中的通配符进行扩展。所以我只是把所有的jar都放到CLASSPATH中，问题就解决了。由于此命令“hadoop classpath --glob”也会生成通配符，它​​解释了为什么 official document说这个

It is not valid to use wildcard syntax for specifying multiple jars. It may be useful to run hadoop classpath --glob or hadoop classpath --jar to generate the correct classpath for your deployment.

昨天我误解了这一段。

另见 Hadoop C++ HDFS test running Exception和 Can JNI be made to honour wildcard expansion in the classpath?