[ https://issues.apache.org/jira/browse/HDFS-16653?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Jingxuan Fu updated HDFS-16653: ------------------------------- Fix Version/s: 3.4.0 3.1.3 > 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 > Fix For: 3.1.3, 3.4.0 > > > > {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-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org