查看JVM参数信息 查看G1堆的使用情况

jinfo -flags [pid]

Attaching to process ID 26841, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.45-b02
Non-default VM flags: -XX:CICompilerCount=15 -XX:ConcGCThreads=7 -XX:+DisableExplicitGC -XX:G1HeapRegionSize=2097152 -XX:G1ReservePercent=25 -XX:GCLogFileSize=134217728 -XX:+HeapDumpOnOutOfMemoryError -XX:InitialHeapSize=4294967296 -XX:InitiatingHeapOccupancyPercent=30 -XX:MarkStackSize=4194304 -XX:MaxHeapSize=4294967296 -XX:MaxNewSize=2575302656 -XX:MinHeapDeltaBytes=2097152 -XX:NumberOfGCLogFiles=5 -XX:+PrintGC -XX:+PrintGCApplicationStoppedTime -XX:+PrintGCDateStamps -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:SoftRefLRUPolicyMSPerMB=0 -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseFastUnorderedTimeStamps -XX:+UseG1GC -XX:+UseGCLogFileRotation 
Command line:  -XX:+UseG1GC -XX:G1ReservePercent=25 -XX:InitiatingHeapOccupancyPercent=30 -XX:SoftRefLRUPolicyMSPerMB=0 -XX:+DisableExplicitGC -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+HeapDumpOnOutOfMemoryError -XX:+PrintGCApplicationStoppedTime -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=5 -XX:GCLogFileSize=128M -DLog4jContextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector -Dfile.encoding=UTF-8 -Xms4g -Xmx4g -Dspring.profiles.active=pro  -Dhome.dir=/application-test -Xloggc:/application-test/logs/gc.log -javaagent:/pinpoint-bootstrap-1.6.2.jar -Dpinpoint.applicationName=application-test -Dpinpoint.profiler.collector.ip=local -Dpinpoint.profiler.sampling.rate=200

jmap -heap [pid]

Attaching to process ID 26841, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.45-b02

using thread-local object allocation.
Garbage-First (G1) GC with 28 thread(s)

Heap Configuration:
   MinHeapFreeRatio         = 40
   MaxHeapFreeRatio         = 70
   MaxHeapSize              = 4294967296 (4096.0MB)
   NewSize                  = 1363144 (1.2999954223632812MB)
   MaxNewSize               = 2575302656 (2456.0MB)
   OldSize                  = 5452592 (5.1999969482421875MB)
   NewRatio                 = 2
   SurvivorRatio            = 8
   MetaspaceSize            = 21807104 (20.796875MB)
   CompressedClassSpaceSize = 1073741824 (1024.0MB)
   MaxMetaspaceSize         = 17592186044415 MB
   G1HeapRegionSize         = 2097152 (2.0MB)

Heap Usage:
G1 Heap:
   regions  = 2048
   capacity = 4294967296 (4096.0MB)
   used     = 2276079248 (2170.6383209228516MB)
   free     = 2018888048 (1925.3616790771484MB)
   52.994099631905556% used
G1 Young Generation:
Eden Space:
   regions  = 623
   capacity = 2181038080 (2080.0MB)
   used     = 1306525696 (1246.0MB)
   free     = 874512384 (834.0MB)
   59.90384615384615% used
Survivor Space:
   regions  = 43
   capacity = 90177536 (86.0MB)
   used     = 90177536 (86.0MB)
   free     = 0 (0.0MB)
   100.0% used
G1 Old Generation:
   regions  = 462
   capacity = 2023751680 (1930.0MB)
   used     = 879376016 (838.6383209228516MB)
   free     = 1144375664 (1091.3616790771484MB)
   43.45276274211666% used

34128 interned Strings occupying 3654448 bytes.