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https://issues.apache.org/jira/browse/HDFS-17546?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17855707#comment-17855707
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ASF GitHub Bot commented on HDFS-17546:
---------------------------------------
NyteKnight opened a new pull request, #6891:
URL: https://github.com/apache/hadoop/pull/6891
### Description of PR
In hadoop environments that rely on NAS to house dfs.hosts file, during FS
hangs (for any reason) the refreshNodes call would infinitely hang (causing a
blocked thread) until the FS returns.
This is due to how Java's Filestream works here:
```
try (Reader input =
new InputStreamReader(
Files.newInputStream(hostFile.toPath()),
StandardCharsets.UTF_8)) {
allDNs = objectMapper.readValue(input,
DatanodeAdminProperties[].class);
} catch (JsonMappingException jme) {
```
In order to fix this we introduce a method (+ new config value) which (if
set) encapsulates the original method in a `Future.Task`. If the Task
> Implementing Timeout for HostFileReader when FS hangs
> -----------------------------------------------------
>
> Key: HDFS-17546
> URL: https://issues.apache.org/jira/browse/HDFS-17546
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Reporter: Simbarashe Dzinamarira
> Assignee: Heagan
> Priority: Minor
> Labels: pull-request-available
>
> Certain implementations of Hadoop have the dfs.hosts file residing on NAS/NFS
> and potentially with symlinks. If the FS hangs for any reason, the
> refreshNodes call would infinitely hang on the HostsFileReader until the FS
> returns.
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