Help Center/ MapReduce Service/ Component Operation Guide (LTS) (Paris Region)/ Using HDFS/ Configuring Memory Management
Updated on 2022-12-14 GMT+08:00
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Configuring Memory Management

Scenario

In HDFS, each file object needs to register corresponding information in the NameNode and occupies certain storage space. As the number of files increases, if the original memory space cannot store the corresponding information, you need to change the memory size.

Configuration Description

Navigation path for setting parameters:

Go to the All Configurations page of HDFS by referring to Modifying Cluster Service Configuration Parameters.

Table 1 Parameter description

Parameter

Description

Default Value

GC_PROFILE

The NameNode memory size depends on the size of FsImage, which can be calculated based on the following formula: FsImage size = Number of files x 900 bytes. You can estimate the memory size of the NameNode of HDFS based on the calculation result.

The value range of this parameter is as follows:

  • high: 4 GB
  • medium: 2 GB
  • low: 256 MB
  • custom: The memory size can be set according to the data size in GC_OPTS.

custom

GC_OPTS

JVM parameter used for garbage collection (GC). This parameter is valid only when GC_PROFILE is set to custom. Ensure that the GC_OPT parameter is set correctly. Otherwise, the process will fail to be started.

NOTICE:

Exercise caution when you modify the configuration. If the configuration is incorrect, the services are unavailable.

-Xms2G -Xmx4G -XX:NewSize=128M -XX:MaxNewSize=256M -XX:MetaspaceSize=128M -XX:MaxMetaspaceSize=128M -XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled -XX:CMSInitiatingOccupancyFraction=65 -XX:+PrintGCDetails -Dsun.rmi.dgc.client.gcInterval=0x7FFFFFFFFFFFFFE -Dsun.rmi.dgc.server.gcInterval=0x7FFFFFFFFFFFFFE -XX:-OmitStackTraceInFastThrow -XX:+PrintGCDateStamps -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=10 -XX:GCLogFileSize=1M -Djdk.tls.ephemeralDHKeySize=2048
Parent topic: Using HDFS