Java JFR view 主要视图
JFR jcmd Java About 8,211 words语法
jcmd <pid> JFR.view hot-methods
热点方法
PS \openjdk-25> jcmd 20064 JFR.view hot-methods
20064:
Java Methods that Execute the Most
Method Samples Percent
------------------------------------------------------------------------------------------------------- ------- -------
sun.security.provider.SHA2.implCompress0(byte[], int) 7 5.19%
jdk.internal.util.ArraysSupport.unsignedHashCode(int, byte[], int, int) 2 1.48%
java.util.ArrayList$Itr.hasNext() 2 1.48%
java.util.zip.ZipUtils.CENNAM(byte[], int) 2 1.48%
java.util.concurrent.ConcurrentHashMap.get(Object) 2 1.48%
java.lang.StringLatin1.hashCode(byte[]) 2 1.48%
java.util.stream.ReduceOps$ReduceOp.evaluateSequential(PipelineHelper, Spliterator) 2 1.48%
java.lang.reflect.Array.newArray(Class, int) 2 1.48%
java.util.HashMap.hash(Object) 2 1.48%
java.lang.CharacterData.of(int) 2 1.48%
java.lang.StringUTF16.newBytesFor(int) 2 1.48%
java.lang.Class.getName() 2 1.48%
java.util.stream.StreamSupport.stream(Spliterator, boolean) 1 0.74%
org.springframework.boot.autoconfigure.condition.ConditionEvaluationReport.recordConditionEvaluation... 1 0.74%
com.sun.org.apache.xerces.internal.parsers.XML11Configuration.setProperty(String, Object) 1 0.74%
org.apache.tomcat.util.IntrospectionUtils.getProperty(Object, String) 1 0.74%
java.lang.String$$StringConcat.0x0000000026128400.concat(Object, Object, Object) 1 0.74%
java.lang.invoke.DelegatingMethodHandle.chooseDelegatingForm(MethodHandle) 1 0.74%
sun.nio.ch.SocketOptionRegistry.findOption(SocketOption, ProtocolFamily) 1 0.74%
sun.security.pkcs11.SunPKCS11.register(SunPKCS11$Descriptor) 1 0.74%
sun.net.www.protocol.jar.JarFileFactory.urlKey(URL) 1 0.74%
jdk.internal.classfile.impl.BufWriterImpl.<init>(ConstantPoolBuilder, ClassFileImpl) 1 0.74%
java.util.ArrayList.iterator() 1 0.74%
java.util.ImmutableCollections$AbstractImmutableList.iterator() 1 0.74%
sun.security.provider.DigestBase.implCompressMultiBlockCheck(byte[], int, int) 1 0.74%
Timespan: 08:59:23 - 09:09:23
方法统计
统计维度包括：调用次数、最短耗时、平均耗时、最大耗时。
备注：Java25新增事件method-timing。
PS \openjdk-25> jcmd 20064 JFR.view method-timing
20064:
Method Timing
Timed Method Invocations Minimum Time Average Time Maximum Time
-------------------------------------------------------------------- ----------- ------------ ------------ ------------
org.springdoc.webmvc.api.OpenApiWebMvcResource.<init>(...) 1 0.837000 ms 0.837000 ms 0.837000 ms
z.note.lite.controller.api.SSEController.mockEmit() 6 0.037400 ms 0.295000 ms 1.530000 ms
z.note.lite.controller.api.UploadController.init() 1 0.262000 ms 0.262000 ms 0.262000 ms
z.note.lite.controller.portal.SitemapController.<init>() 1 0.037600 ms 0.037600 ms 0.037600 ms
z.note.lite.controller.api.LoginController.<clinit>() 1 0.024500 ms 0.024500 ms 0.024500 ms
z.note.lite.controller.mobile.MobileController.<clinit>() 1 0.016000 ms 0.016000 ms 0.016000 ms
z.note.lite.controller.api.UploadController.<clinit>() 1 0.015500 ms 0.015500 ms 0.015500 ms
z.note.lite.controller.api.SysUserMgmtController.<clinit>() 1 0.015200 ms 0.015200 ms 0.015200 ms
z.note.lite.controller.api.SearchMgmtController.<init>() 1 0.012100 ms 0.012100 ms 0.012100 ms
z.note.lite.controller.api.CleanCacheController.<init>() 1 0.008670 ms 0.008670 ms 0.008670 ms
z.note.lite.controller.api.SSEController.<init>() 1 0.006840 ms 0.006840 ms 0.006840 ms
org.springdoc.webmvc.ui.SwaggerConfigResource.<init>(...) 1 0.005750 ms 0.005750 ms 0.005750 ms
z.note.lite.controller.api.PageViewMgmtController.<init>() 1 0.004470 ms 0.004470 ms 0.004470 ms
z.note.lite.controller.api.IpMgmtController.<init>() 1 0.004320 ms 0.004320 ms 0.004320 ms
z.note.lite.controller.api.TopicMgmtController.<init>() 1 0.003990 ms 0.003990 ms 0.003990 ms
z.note.lite.controller.api.LoginController.<init>() 1 0.003860 ms 0.003860 ms 0.003860 ms
z.note.lite.controller.api.LinkMgmtController.<init>() 1 0.003460 ms 0.003460 ms 0.003460 ms
z.note.lite.controller.api.PostMgmtController.<init>() 1 0.003430 ms 0.003430 ms 0.003430 ms
z.note.lite.controller.api.UploadController.<init>() 1 0.003050 ms 0.003050 ms 0.003050 ms
z.note.lite.controller.mobile.MobileController.<init>() 1 0.002620 ms 0.002620 ms 0.002620 ms
z.note.lite.controller.api.SysUserMgmtController.<init>() 1 0.002320 ms 0.002320 ms 0.002320 ms
z.note.lite.controller.mobile.MobileController.post(Integer) 0 N/A N/A N/A
...
Timespan: 09:01:24 - 09:11:24
垃圾回收
PS openjdk-25> jcmd 1240 JFR.view gc
1240:
Garbage Collections
Start GC ID Type Heap Before GC Heap After GC Longest Pause
-------- ----- ------------------------ -------------- ------------- -------------
11:01:57 0 Young Garbage Collection 29.1 MB 7.9 MB 8.91 ms
11:02:00 1 Young Garbage Collection 57.9 MB 12.7 MB 22.0 ms
11:02:00 2 Young Garbage Collection 25.7 MB 13.6 MB 7.58 ms
11:02:00 3 Old Garbage Collection 13.6 MB 14.6 MB 2.75 ms
11:02:01 4 Young Garbage Collection 37.6 MB 16.5 MB 12.5 ms
11:02:02 5 Young Garbage Collection 35.5 MB 19.0 MB 11.2 ms
11:02:02 6 Young Garbage Collection 38.0 MB 20.3 MB 10.3 ms
11:02:03 7 Young Garbage Collection 40.3 MB 21.7 MB 8.80 ms
11:02:03 8 Young Garbage Collection 41.7 MB 23.8 MB 10.8 ms
11:02:04 9 Young Garbage Collection 42.8 MB 25.8 MB 10.9 ms
11:02:04 10 Old Garbage Collection 25.8 MB 26.8 MB 7.03 ms
11:02:04 11 Young Garbage Collection 49.8 MB 27.9 MB 7.66 ms
11:02:05 12 Young Garbage Collection 50.9 MB 29.5 MB 12.4 ms
Timespan: 10:52:05 - 11:02:05
堆配置
PS \openjdk-25> jcmd 1240 JFR.view heap-configuration
1240:
Heap Configuration
------------------
Initial Heap Size: 128.0 MB
Minimum Heap Size: 8.0 MB
Maximum Heap Size: 2.0 GB
If Compressed Oops Are Used: true
Compressed Oops Mode: 32-bit
Timespan: 10:53:52 - 11:03:52
Views: 5 · Posted: 2026-01-12
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