查看當前Linux系統中vm.max_map_count變量的值，命令如下：

sysctl vm.max_map_count

執行結果的樣例，如下：

vm.max_map_count = 65530

修改參數vm.max_map_count的值，命令如下：

sysctl -w vm.max_map_count=262144

執行結果的樣例，如下：

vm.max_map_count = 262144

為保證重啟Linux系統后vm.max_map_count的取值依然生效，可以修改Linux系統配置文件/etc/sysctl.conf，追加如下內容：

vm.max_map_count=262144

配置文件/etc/sysctl.conf的內容，樣例如下：

#
# /etc/sysctl.conf - Configuration file for setting system variables
# See /etc/sysctl.d/ for additional system variables.
# See sysctl.conf (5) for information.
##kernel.domainname = example.com# Uncomment the following to stop low-level messages on console
#kernel.printk = 3 4 1 3##############################################################3
# Functions previously found in netbase
## Uncomment the next two lines to enable Spoof protection (reverse-path filter)
# Turn on Source Address Verification in all interfaces to
# prevent some spoofing attacks
#net.ipv4.conf.default.rp_filter=1
#net.ipv4.conf.all.rp_filter=1# Uncomment the next line to enable TCP/IP SYN cookies
# See http://lwn.net/Articles/277146/
# Note: This may impact IPv6 TCP sessions too
#net.ipv4.tcp_syncookies=1# Uncomment the next line to enable packet forwarding for IPv4
#net.ipv4.ip_forward=1# Uncomment the next line to enable packet forwarding for IPv6
#  Enabling this option disables Stateless Address Autoconfiguration
#  based on Router Advertisements for this host
#net.ipv6.conf.all.forwarding=1###################################################################
# Additional settings - these settings can improve the network
# security of the host and prevent against some network attacks
# including spoofing attacks and man in the middle attacks through
# redirection. Some network environments, however, require that these
# settings are disabled so review and enable them as needed.
#
# Do not accept ICMP redirects (prevent MITM attacks)
#net.ipv4.conf.all.accept_redirects = 0
#net.ipv6.conf.all.accept_redirects = 0
# _or_
# Accept ICMP redirects only for gateways listed in our default
# gateway list (enabled by default)
# net.ipv4.conf.all.secure_redirects = 1
#
# Do not send ICMP redirects (we are not a router)
#net.ipv4.conf.all.send_redirects = 0
#
# Do not accept IP source route packets (we are not a router)
#net.ipv4.conf.all.accept_source_route = 0
#net.ipv6.conf.all.accept_source_route = 0
#
# Log Martian Packets
#net.ipv4.conf.all.log_martians = 1
####################################################################
# Magic system request Key
# 0=disable, 1=enable all, >1 bitmask of sysrq functions
# See https://www.kernel.org/doc/html/latest/admin-guide/sysrq.html
# for what other values do
#kernel.sysrq=438
vm.swappiness=20
vm.max_map_count=262144

已知Elasticsearch進程的pid為19483，查看Elasticsearch進程當前占用的mmap的數量，命令樣例如下：

wc -l /proc/19483/maps

執行結果的樣例，如下：

414 /proc/19483/maps

相關資料

• Virtual memory
• Elasticsearch 內存占用分析及 page cache 監控
• Elasticsearch
• Linux修改文件句柄數及vm.max_map_count、stack size的大小
• elasticsearch vm.max_map_count
• Kafka之 vm.max_map_count
• 大數據技術之Elasticsearch