You are viewing a plain text version of this content. The canonical link for it is here.
Posted to hdfs-issues@hadoop.apache.org by "ASF GitHub Bot (Jira)" <ji...@apache.org> on 2022/09/01 07:05:00 UTC
[jira] [Commented] (HDFS-16653) Safe mode related operations cannot be performed when “dfs.client.mmap.cache.size” is set to a negative number
[ https://issues.apache.org/jira/browse/HDFS-16653?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17598767#comment-17598767 ]
ASF GitHub Bot commented on HDFS-16653:
---------------------------------------
Likkey closed pull request #4707: HDFS-16653.Safe mode related operations cannot be performed when “dfs.client.mmap.cache.size” is set to a negative number
URL: https://github.com/apache/hadoop/pull/4707
> Safe mode related operations cannot be performed when “dfs.client.mmap.cache.size” is set to a negative number
> --------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-16653
> URL: https://issues.apache.org/jira/browse/HDFS-16653
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: dfsadmin
> Affects Versions: 3.1.3
> Environment: Linux version 4.15.0-142-generic (buildd@lgw01-amd64-039) (gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.12))
> Reporter: Jingxuan Fu
> Assignee: Jingxuan Fu
> Priority: Major
> Labels: pull-request-available
>
>
> {code:java}
> <property>
> <name>dfs.client.mmap.cache.size</name>
> <value>256</value>
> <description>
> When zero-copy reads are used, the DFSClient keeps a cache of recently used
> memory mapped regions. This parameter controls the maximum number of
> entries that we will keep in that cache.
> The larger this number is, the more file descriptors we will potentially
> use for memory-mapped files. mmaped files also use virtual address space.
> You may need to increase your ulimit virtual address space limits before
> increasing the client mmap cache size.
>
> Note that you can still do zero-copy reads when this size is set to 0.
> </description>
> </property>
> {code}
> When the configuration item “dfs.client.mmap.cache.size” is set to a negative number, it will cause /hadoop/bin hdfs dfsadmin -safemode provides all the operation options including enter, leave, get, wait and forceExit are invalid, the terminal returns security mode is null and no exceptions are thrown.
> {code:java}
> hadoop@ljq1:~/hadoop-3.1.3-work/etc/hadoop$ hdfs dfsadmin -safemode leave
> safemode: null
> Usage: hdfs dfsadmin [-safemode enter | leave | get | wait | forceExit] {code}
> In summary, I think we need to improve the check mechanism related to this configuration item, and give a clear indication when the configuration is abnormal in order to solve the problem in time and reduce the impact on the safe mode related operations.
>
>
>
>
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
---------------------------------------------------------------------
To unsubscribe, e-mail: hdfs-issues-unsubscribe@hadoop.apache.org
For additional commands, e-mail: hdfs-issues-help@hadoop.apache.org