向HDFS文件append新内容

在hadoop1.2.1中，网上有很多文章说这个版本不支持文件追加模式，设置了

<property>
<name>dfs.support.append</name>
<value>true</value>
</property>

无效

由于我现在做的项目需要这个功能，而升级hadoop似乎不太可能，然后查看源码发现，其中allowBrokenAppend是用于判断是否支持追加的标识符

this.allowBrokenAppend = conf.getBoolean("dfs.support.broken.append", false);
if (conf.getBoolean("dfs.support.append", false)) {
LOG.warn("The dfs.support.append option is in your configuration, " +
"however append is not supported. This configuration option " +
"is no longer required to enable sync");
}

<pre name="code" class="java"> LocatedBlock appendFile(String src, String holder, String clientMachine
) throws IOException {
if (!allowBrokenAppend) {
throw new IOException("Append is not supported. " +
"Please see the dfs.support.append configuration parameter");
}
startFileInternal(src, null, holder, clientMachine, false, true,
false, (short)maxReplication, (long)0);
getEditLog().logSync();

看到这里就很明白了吧，dfs.support.append属性已经作废不起作用了，如果想支持追加模式需要以下设置

<property>
<name>dfs.support.broken.append</name>
<value>true</value>
</property>