## JVM configuration
################################################################
## IMPORTANT: JVM heap size
################################################################
##
## You should always set the min and max JVM heap
## size to the same value. For example, to set
## the heap to 4 GB, set:
##
## -Xms4g
## -Xmx4g
##
## See https://www.elastic.co/guide/en/elasticsearch/reference/current/heap-size.html
## for more information
##
################################################################
# Xms represents the initial size of total heap space
# Xmx represents the maximum size of total heap space
## JVM 堆大小设置
-Xms1g
-Xmx1g
################################################################
## Expert settings
################################################################
##
## All settings below this section are considered
## expert settings. Don't tamper with them unless
## you understand what you are doing
##
################################################################
## GC configuration
-XX:+UseConcMarkSweepGC
@## 即CMS收集，设置年老代为并发收集
-XX:CMSInitiatingOccupancyFraction=75
@## 表示年老代内存空间使用到75%时就开始执行CMS收集，以确保年老代有足够的空间接纳来自年轻代的对象，避免Full GC的发生
-XX:+UseCMSInitiatingOccupancyOnly
@## 扩展CMS垃圾回收机制
@## https://www.cnblogs.com/Leo_wl/p/5393300.html
## optimizations
# pre-touch memory pages used by the JVM during initialization
-XX:+AlwaysPreTouch
@## JVM就会先访问所有分配给它的内存,让操作系统把内存真正的分配给JVM
@## https://blog.csdn.net/linsongbin1/article/details/55049477
## basic
# explicitly set the stack size
-Xss1m
# set to headless, just in case
-Djava.awt.headless=true
@## 如果没有安装图形界面，可以在Java运行时加上参数：-Djava.awt.headless=true
# ensure UTF-8 encoding by default (e.g. filenames)
-Dfile.encoding=UTF-8
# use our provided JNA always versus the system one
-Djna.nosys=true
# turn off a JDK optimization that throws away stack traces for common
# exceptions because stack traces are important for debugging
-XX:-OmitStackTraceInFastThrow
@## 强制要求JVM始终抛出含堆栈的异常(-XX:-OmitStackTraceInFastThrow)
# flags to configure Netty
-Dio.netty.noUnsafe=true
-Dio.netty.noKeySetOptimization=true
-Dio.netty.recycler.maxCapacityPerThread=0
@## 设置io.netty.noUnsafe属性为true，则默认会使用Heap堆内存创建ByteBuf
# log4j 2
-Dlog4j.shutdownHookEnabled=false
-Dlog4j2.disable.jmx=true
-Djava.io.tmpdir=${ES_TMPDIR}
## heap dumps
# generate a heap dump when an allocation from the Java heap fails
# heap dumps are created in the working directory of the JVM
-XX:+HeapDumpOnOutOfMemoryError
# specify an alternative path for heap dumps
# ensure the directory exists and has sufficient space
#-XX:HeapDumpPath=/heap/dump/path
@## 参数表示生成DUMP文件的路径
## JDK 8 GC logging
8:-XX:+PrintGCDetails
8:-XX:+PrintGCDateStamps
8:-XX:+PrintTenuringDistribution
8:-XX:+PrintGCApplicationStoppedTime
8:-Xloggc:logs/gc.log
8:-XX:+UseGCLogFileRotation
8:-XX:NumberOfGCLogFiles=32
8:-XX:GCLogFileSize=64m
# JDK 9+ GC logging
9-:-Xlog:gc*,gc+age=trace,safepoint:file=logs/gc.log:utctime,pid,tags:filecount=32,filesize=64m
# due to internationalization enhancements in JDK 9 Elasticsearch need to set the provider to COMPAT otherwise
# time/date parsing will break in an incompatible way for some date patterns and locals
9-:-Djava.locale.providers=COMPAT