The startup command for the application is as follows:
java -server -Xms15g -Xmx15g -XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled -XX:+UseCMSInitiatingOccupancyOnly -XX:CMSInitiatingOccupancyFraction=77 -XX:+ScavengeBeforeFullGC -XX:+CMSScavengeBeforeRemark -Djava.security.egd=file:/dev/./urandom -jar /app.jar --spring.profiles.active=prod
The following information can be obtained from the JVM command of arthas:
RUNTIME
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MACHINE-NAME 7@authserver-5fc5c7c775-9fs2m
JVM-START-TIME 2020-04-15 00:04:27
MANAGEMENT-SPEC-VERSION 1.2
SPEC-NAME Java Virtual Machine Specification
SPEC-VENDOR Oracle Corporation
SPEC-VERSION 1.8
VM-NAME Java HotSpot(TM) 64-Bit Server VM
VM-VENDOR Oracle Corporation
VM-VERSION 25.111-b14
INPUT-ARGUMENTS -javaagent:/var/agent/pinpoint-agent/pinpoint-bootstrap.jar
-Xms15g
-Xmx15g
-XX:+UseConcMarkSweepGC
-XX:+CMSParallelRemarkEnabled
-XX:+UseCMSInitiatingOccupancyOnly
-XX:CMSInitiatingOccupancyFraction=77
-XX:+ScavengeBeforeFullGC
-XX:+CMSScavengeBeforeRemark
-Djava.security.egd=file:/dev/./urandom
CLASS-PATH /app.jar:/var/agent/pinpoint-agent/pinpoint-bootstrap.jar
BOOT-CLASS-PATH /usr/java/jre1.8.0_111/lib/resources.jar:/usr/java/jre1.8.0_111/lib/rt.jar:/usr/java/jre1.8.0_111/lib/sunrsasign.jar
:/usr/java/jre1.8.0_111/lib/jsse.jar:/usr/java/jre1.8.0_111/lib/jce.jar:/usr/java/jre1.8.0_111/lib/charsets.jar:/usr
/java/jre1.8.0_111/lib/jfr.jar:/usr/java/jre1.8.0_111/classes
LIBRARY-PATH /usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
CLASS-LOADING
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
LOADED-CLASS-COUNT 21926
TOTAL-LOADED-CLASS-COUNT 21944
UNLOADED-CLASS-COUNT 18
IS-VERBOSE false
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
COMPILATION
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
NAME HotSpot 64-Bit Tiered Compilers
TOTAL-COMPILE-TIME 366850(ms)
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
GARBAGE-COLLECTORS
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
ParNew 1797/78247(ms)
[count/time]
ConcurrentMarkSweep 3/460(ms)
[count/time]
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MEMORY-MANAGERS
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
CodeCacheManager Code Cache
Metaspace Manager Metaspace
Compressed Class Space
ParNew Par Eden Space
Par Survivor Space
ConcurrentMarkSweep Par Eden Space
Par Survivor Space
CMS Old Gen
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MEMORY
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
HEAP-MEMORY-USAGE 15992750080(14.9 GiB)/16106127360(15.0 GiB)/15992750080(14.9 GiB)/2393542120(2.2 GiB)
[committed/init/max/used]
NO-HEAP-MEMORY-USAGE 255647744(243.8 MiB)/2555904(2.4 MiB)/-1(-1 B)/247922192(236.4 MiB)
[committed/init/max/used]
PENDING-FINALIZE-COUNT 0
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
OPERATING-SYSTEM
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
OS Linux
ARCH amd64
PROCESSORS-COUNT 16
LOAD-AVERAGE 5.08
VERSION 4.4.0-141-generic
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THREAD
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
COUNT 256
DAEMON-COUNT 103
PEAK-COUNT 263
STARTED-COUNT 41467
DEADLOCK-COUNT 0
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
FILE-DESCRIPTOR
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
MAX-FILE-DESCRIPTOR-COUNT 1048576
OPEN-FILE-DESCRIPTOR-COUNT 811
Affect(row-cnt:0) cost in 6 ms.
From the above information, you can see that both committed/init of the JVM heap are about 15GiB.
However, from the system top command or the free command, the memory footprint of this process is only 3.712g
the result of the top command is shown
the result of the free command is shown
