Java 不同垃圾回收器占用的内存大小
GC JVM Java About 7,694 words需求
Java
内存中除了堆内存外,还有堆外内存,如:垃圾回收器就会占用一定的堆外内存。
对于在Kubernetes
中部署的服务,如果频繁被OOM
,需要关注堆外内存。GC
也是占用内存的一部分。
基准参数
- 最大堆内存:
2G
- 最小堆内存:
2G
结论
GC | 占用内存 |
---|---|
SerialGC | 6.7M |
ParallelGC | 106M |
G1GC | 133M |
ShenandoahGC | 37M~69M |
ZGC | 96M~8256M |
SerialGC
java -Xmx2G -Xms2G -XX:+UseSerialGC -XshowSettings:vm -XX:+PrintCommandLineFlags -XX:NativeMemoryTracking=summary -XX:+UnlockDiagnosticVMOptions -XX:+PrintNMTStatistics -version
NMT
显示GC
占用:7034970
字节(6.7
M)
❯ java -Xmx2G -Xms2G -XX:+UseSerialGC -XshowSettings:vm -XX:+PrintCommandLineFlags -XX:NativeMemoryTracking=summary -XX:+UnlockDiagnosticVMOptions -XX:+PrintNMTStatistics -version
-XX:InitialHeapSize=2147483648 -XX:MaxHeapSize=2147483648 -XX:NativeMemoryTracking=summary -XX:+PrintCommandLineFlags -XX:+PrintNMTStatistics -XX:ReservedCodeCacheSize=251658240 -XX:+SegmentedCodeCache -XX:+UnlockDiagnosticVMOptions -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseSerialGC
VM settings:
Min. Heap Size: 2.00G
Max. Heap Size: 2.00G
Using VM: OpenJDK 64-Bit Server VM
openjdk version "11.0.17" 2022-10-18
OpenJDK Runtime Environment Temurin-11.0.17+8 (build 11.0.17+8)
OpenJDK 64-Bit Server VM Temurin-11.0.17+8 (build 11.0.17+8, mixed mode)
Native Memory Tracking:
Total: reserved=3514969375, committed=2191551775
- Java Heap (reserved=2147483648, committed=2147483648)
(mmap: reserved=2147483648, committed=2147483648)
- GC (reserved=7034970, committed=7034970)
(malloc=22618 #116)
(mmap: reserved=7012352, committed=7012352)
ParallelGC
java -Xmx2G -Xms2G -XX:+UseParallelGC -XshowSettings:vm -XX:+PrintCommandLineFlags -XX:NativeMemoryTracking=summary -XX:+UnlockDiagnosticVMOptions -XX:+PrintNMTStatistics -version
NMT
显示GC
占用:111283672
字节(106
M)
❯ java -Xmx2G -Xms2G -XX:+UseParallelGC -XshowSettings:vm -XX:+PrintCommandLineFlags -XX:NativeMemoryTracking=summary -XX:+UnlockDiagnosticVMOptions -XX:+PrintNMTStatistics -version
-XX:InitialHeapSize=2147483648 -XX:MaxHeapSize=2147483648 -XX:NativeMemoryTracking=summary -XX:+PrintCommandLineFlags -XX:+PrintNMTStatistics -XX:ReservedCodeCacheSize=251658240 -XX:+SegmentedCodeCache -XX:+UnlockDiagnosticVMOptions -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseParallelGC
VM settings:
Min. Heap Size: 2.00G
Max. Heap Size: 2.00G
Using VM: OpenJDK 64-Bit Server VM
openjdk version "11.0.17" 2022-10-18
OpenJDK Runtime Environment Temurin-11.0.17+8 (build 11.0.17+8)
OpenJDK 64-Bit Server VM Temurin-11.0.17+8 (build 11.0.17+8, mixed mode)
Native Memory Tracking:
Total: reserved=3621375483, committed=2297957883
- Java Heap (reserved=2147483648, committed=2147483648)
(mmap: reserved=2147483648, committed=2147483648)
- GC (reserved=111283672, committed=111283672)
(malloc=32804312 #187)
(mmap: reserved=78479360, committed=78479360)
G1GC
java -Xmx2G -Xms2G -XX:+UseG1GC -XshowSettings:vm -XX:+PrintCommandLineFlags -XX:NativeMemoryTracking=summary -XX:+UnlockDiagnosticVMOptions -XX:+PrintNMTStatistics -version
NMT
显示GC
占用:139719719
字节(133M
)
❯ java -Xmx2G -Xms2G -XX:+UseG1GC -XshowSettings:vm -XX:+PrintCommandLineFlags -XX:NativeMemoryTracking=summary -XX:+UnlockDiagnosticVMOptions -XX:+PrintNMTStatistics -version
-XX:G1ConcRefinementThreads=9 -XX:GCDrainStackTargetSize=64 -XX:InitialHeapSize=2147483648 -XX:MaxHeapSize=2147483648 -XX:NativeMemoryTracking=summary -XX:+PrintCommandLineFlags -XX:+PrintNMTStatistics -XX:ReservedCodeCacheSize=251658240 -XX:+SegmentedCodeCache -XX:+UnlockDiagnosticVMOptions -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseG1GC
VM settings:
Min. Heap Size: 2.00G
Max. Heap Size: 2.00G
Using VM: OpenJDK 64-Bit Server VM
openjdk version "11.0.17" 2022-10-18
OpenJDK Runtime Environment Temurin-11.0.17+8 (build 11.0.17+8)
OpenJDK 64-Bit Server VM Temurin-11.0.17+8 (build 11.0.17+8, mixed mode)
Native Memory Tracking:
Total: reserved=3658550668, committed=2335133068
- Java Heap (reserved=2147483648, committed=2147483648)
(mmap: reserved=2147483648, committed=2147483648)
- GC (reserved=139719719, committed=139719719)
(malloc=25916455 #14644)
(mmap: reserved=113803264, committed=113803264)
ShenandoahGC
ShenandoahGC
是Red Hat
贡献给OpenJDK
的垃圾回收器,OpenJDK 12+
默认包含了该GC
,OpenJDK 11.0.9
后中也引入了该GC
。
注意:所有Oracle
的JDK
,任何版本,都没有引入该GC
。
参考文档:https://wiki.openjdk.org/display/shenandoah/Main
java -Xmx2G -Xms2G -XX:+UseShenandoahGC -XshowSettings:vm -XX:+PrintCommandLineFlags -XX:NativeMemoryTracking=summary -XX:+UnlockDiagnosticVMOptions -XX:+PrintNMTStatistics -version
NMT
显示GC
占用:已提交39276392
字节(37M
),保留72830824
字节(69M
)
❯ java -Xmx2G -Xms2G -XX:+UseShenandoahGC -XshowSettings:vm -XX:+PrintCommandLineFlags -XX:NativeMemoryTracking=summary -XX:+UnlockDiagnosticVMOptions -XX:+PrintNMTStatistics -version
-XX:InitialHeapSize=2147483648 -XX:MaxHeapSize=2147483648 -XX:NativeMemoryTracking=summary -XX:+PrintCommandLineFlags -XX:+PrintNMTStatistics -XX:ReservedCodeCacheSize=251658240 -XX:+SegmentedCodeCache -XX:+UnlockDiagnosticVMOptions -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseShenandoahGC
VM settings:
Min. Heap Size: 2.00G
Max. Heap Size: 2.00G
Using VM: OpenJDK 64-Bit Server VM
openjdk version "11.0.17" 2022-10-18
OpenJDK Runtime Environment Temurin-11.0.17+8 (build 11.0.17+8)
OpenJDK 64-Bit Server VM Temurin-11.0.17+8 (build 11.0.17+8, mixed mode)
Native Memory Tracking:
Total: reserved=3587868112, committed=2230896080
- Java Heap (reserved=2147483648, committed=2147483648)
(mmap: reserved=2147483648, committed=2147483648)
- GC (reserved=72830824, committed=39276392)
(malloc=5427048 #652)
(mmap: reserved=67403776, committed=33849344)
ZGC
java -Xmx2G -Xms2G -XX:+UseZGC -XshowSettings:vm -XX:+PrintCommandLineFlags -XX:NativeMemoryTracking=summary -XX:+UnlockDiagnosticVMOptions -XX:+PrintNMTStatistics -version
NMT
显示GC
占用:已提交100813366
字节(96M
),保留8657193526
字节(8256M
)
❯ java -Xmx2G -Xms2G -XX:+UseZGC -XshowSettings:vm -XX:+PrintCommandLineFlags -XX:NativeMemoryTracking=summary -XX:+UnlockDiagnosticVMOptions -XX:+PrintNMTStatistics -version
[0.002s][warning][gc,jvmci] Setting EnableJVMCI to false as selected GC does not support JVMCI: z gc
-XX:+EnableJVMCIProduct -XX:InitialHeapSize=2147483648 -XX:MaxHeapSize=2147483648 -XX:MinHeapSize=2147483648 -XX:NativeMemoryTracking=summary -XX:+PrintCommandLineFlags -XX:+PrintNMTStatistics -XX:ReservedCodeCacheSize=251658240 -XX:+SegmentedCodeCache -XX:ThreadPriorityPolicy=1 -XX:+UnlockDiagnosticVMOptions -XX:-UnlockExperimentalVMOptions -XX:+UseCompressedClassPointers -XX:-UseCompressedOops -XX:+UseZGC
VM settings:
Min. Heap Size: 2.00G
Max. Heap Size: 2.00G
Using VM: OpenJDK 64-Bit Server VM
openjdk version "17.0.5" 2022-10-18 LTS
OpenJDK Runtime Environment GraalVM 22.3.0 (build 17.0.5+8-LTS)
OpenJDK 64-Bit Server VM GraalVM 22.3.0 (build 17.0.5+8-LTS, mixed mode)
Native Memory Tracking:
Total: reserved=115268659647, committed=2310629823
- Java Heap (reserved=103079215104, committed=2147483648)
(mmap: reserved=103079215104, committed=2147483648)
- GC (reserved=8657193526, committed=100813366)
(malloc=150070 #396)
(mmap: reserved=8657043456, committed=100663296)
Views: 600 · Posted: 2023-12-27
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