JVM进程常驻集大小“等于”最大堆大小，而不是当前堆大小

在阅读了关于jvm内存（这里，在这里，其他的我忘记了…）之后，我期待我的java进程的驻留集大小大致等于当前的堆空间容量。这不是数字所说的，它似乎大致等于最大的堆空间容量：

居民套装尺寸：

# echo 0 $(cat /proc/1/smaps | grep Rss | awk '{print $2}' | sed 's#^#+#') | bc 11507912 # ps -C java -O rss | gawk '{ count ++; sum += $2 }; END {count --; print "Number of processes =",count; print "Memory usage per process =",sum/1024/count, "MB"; print "Total memory usage =", sum/1024, "MB" ;};' Number of processes = 1 Memory usage per process = 11237.8 MB Total memory usage = 11237.8 MB

Java堆

 # jmap -heap 1 Attaching to process ID 1, please wait... Debugger attached successfully. Server compiler detected. JVM version is 24.55-b03 using thread-local object allocation. Garbage-First (G1) GC with 18 thread(s) Heap Configuration: MinHeapFreeRatio = 10 MaxHeapFreeRatio = 20 MaxHeapSize = 10737418240 (10240.0MB) NewSize = 1363144 (1.2999954223632812MB) MaxNewSize = 17592186044415 MB OldSize = 5452592 (5.1999969482421875MB) NewRatio = 2 SurvivorRatio = 8 PermSize = 20971520 (20.0MB) MaxPermSize = 85983232 (82.0MB) G1HeapRegionSize = 2097152 (2.0MB) Heap Usage: G1 Heap: regions = 2560 capacity = 5368709120 (5120.0MB) used = 1672045416 (1594.586769104004MB) free = 3696663704 (3525.413230895996MB) 31.144272834062576% used G1 Young Generation: Eden Space: regions = 627 capacity = 3279945728 (3128.0MB) used = 1314914304 (1254.0MB) free = 1965031424 (1874.0MB) 40.089514066496164% used Survivor Space: regions = 49 capacity = 102760448 (98.0MB) used = 102760448 (98.0MB) free = 0 (0.0MB) 100.0% used G1 Old Generation: regions = 147 capacity = 1986002944 (1894.0MB) used = 252273512 (240.5867691040039MB) free = 1733729432 (1653.413230895996MB) 12.702574926293766% used Perm Generation: capacity = 39845888 (38.0MB) used = 38884120 (37.082786560058594MB) free = 961768 (0.9172134399414062MB) 97.58628042120682% used 14654 interned Strings occupying 2188928 bytes.

我的期望错了吗？我应该期待什么？
我需要堆空间能够在尖峰期间增长（为了避免非常慢的Full GC），但是我希望剩下的时间尽可能的减less驻留集的大小，以便使服务器上运行的其他进程受益。有没有更好的方法来实现呢？

 Linux 3.13.0-32-generic x86_64 java version "1.7.0_55" Running in Docker version 1.1.2

Java正在运行elasticsearch 1.2.0：

 /usr/bin/java -Xms5g -Xmx10g -XX:MinHeapFreeRatio=10 -XX:MaxHeapFreeRatio=20 -Xss256k -Djava.awt.headless=true -XX:+UseG1GC -XX:MaxGCPauseMillis=350 -XX:InitiatingHeapOccupancyPercent=45 -XX:+AggressiveOpts -XX:+UseCompressedOops -XX:-OmitStackTraceInFastThrow -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintClassHistogram -XX:+PrintTenuringDistribution -XX:+PrintGCApplicationStoppedTime -XX:+PrintGCApplicationConcurrentTime -Xloggc:/opt/elasticsearch/logs/gc.log -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/opt elasticsearch/logs/heapdump.hprof -XX:ErrorFile=/opt/elasticsearch/logs/hs_err.log -Des.logger.port=99999 -Des.logger.host=999.999.999.999 -Delasticsearch -Des.foreground=yes -Des.path.home=/opt/elasticsearch -cp :/opt/elasticsearch/lib/elasticsearch-1.2.0.jar:/opt/elasticsearch/lib/*:/opt/elasticsearch/lib/sigar/* org.elasticsearch.bootstrap.Elasticsearch

实际上有5个elasticsearch节点，每个在不同的docker集装箱。所有的内存使用率都差不多。有关指数的一些统计数据：

 size: 9.71Gi (19.4Gi) docs: 3,925,398 (4,052,694)