ps -ef | grep java root 1426 1359 0 10:30 pts/0 00:00:00 grep java root 7807 1 0 Apr28 ? 00:22:52 /usr/java/jdk1.8.0_45/bin/java -Djava.util.logging.config.file=/opt/apache-tomcat-8.0.30/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.endorsed.dirs=/opt/apache-tomcat-8.0.30/endorsed -classpath /opt/apache-tomcat-8.0.30/bin/bootstrap.jar:/opt/apache-tomcat-8.0.30/bin/tomcat-juli.jar -Dcatalina.base=/opt/apache-tomcat-8.0.30 -Dcatalina.home=/opt/apache-tomcat-8.0.30 -Djava.io.tmpdir=/opt/apache-tomcat-8.0.30/temp org.apache.catalina.startup.Bootstrap start
jmap 7807
Attaching to process ID 7807, please wait... Debugger attached successfully. Server compiler detected. JVM version is 25.45-b02 0x0000000000400000 7K /usr/java/jdk1.8.0_45/bin/java 0x00007f17958dd000 36K /usr/java/jdk1.8.0_45/jre/lib/amd64/libawt_headless.so 0x00007f1795ae4000 754K /usr/java/jdk1.8.0_45/jre/lib/amd64/libawt.so 0x00007f17eaee5000 108K /lib64/libresolv-2.12.so 0x00007f17ecf03000 26K /lib64/libnss_dns-2.12.so 0x00007f17ee21f000 88K /lib64/libgcc_s-4.4.7-20120601.so.1 0x00007f17ee435000 250K /usr/java/jdk1.8.0_45/jre/lib/amd64/libsunec.so 0x00007f17ee97d000 90K /usr/java/jdk1.8.0_45/jre/lib/amd64/libnio.so 0x00007f17eeb8e000 113K /usr/java/jdk1.8.0_45/jre/lib/amd64/libnet.so 0x00007f17eeda5000 48K /usr/java/jdk1.8.0_45/jre/lib/amd64/libmanagement.so 0x00007f180880a000 121K /usr/java/jdk1.8.0_45/jre/lib/amd64/libzip.so 0x00007f1808a25000 64K /lib64/libnss_files-2.12.so 0x00007f1808c33000 220K /usr/java/jdk1.8.0_45/jre/lib/amd64/libjava.so 0x00007f1808e5f000 64K /usr/java/jdk1.8.0_45/jre/lib/amd64/libverify.so 0x00007f180906e000 42K /lib64/librt-2.12.so 0x00007f1809276000 582K /lib64/libm-2.12.so 0x00007f18094fa000 16440K /usr/java/jdk1.8.0_45/jre/lib/amd64/server/libjvm.so 0x00007f180a4c2000 1876K /lib64/libc-2.12.so 0x00007f180a856000 19K /lib64/libdl-2.12.so 0x00007f180aa5a000 100K /usr/java/jdk1.8.0_45/lib/amd64/jli/libjli.so 0x00007f180ac70000 139K /lib64/libpthread-2.12.so 0x00007f180ae8d000 150K /lib64/ld-2.12.so
jmap -heap 7807
Attaching to process ID 7807, please wait... Debugger attached successfully. Server compiler detected. JVM version is 25.45-b02 using thread-local object allocation. Parallel GC with 2 thread(s) Heap Configuration: MinHeapFreeRatio = 0 MaxHeapFreeRatio = 100 MaxHeapSize = 1006632960 (960.0MB) NewSize = 20971520 (20.0MB) MaxNewSize = 335544320 (320.0MB) OldSize = 41943040 (40.0MB) NewRatio = 2 SurvivorRatio = 8 MetaspaceSize = 21807104 (20.796875MB) CompressedClassSpaceSize = 1073741824 (1024.0MB) MaxMetaspaceSize = 17592186044415 MB G1HeapRegionSize = 0 (0.0MB) Heap Usage: PS Young Generation Eden Space: ---------------------------------------- Garden of Eden capacity = 122683392 (117.0MB) used = 84779408 (80.85194396972656MB) free = 37903984 (36.14805603027344MB) 69.10422561515091% used From Space: ---------------------------------------- Young Generation (Survivor Paradise 1 ) capacity = 524288 (0.5MB) used = 32768 (0.03125MB) free = 491520 (0.46875MB) 6.25% used To Space: -------------------------------------------- Young Generation (Survivor Paradise 2) capacity = 38273024 (36.5MB) used = 0 (0.0MB) free = 38273024 (36.5MB) 0.0% used PS Old Generation ---------------------------------- Old age (lifelong nursing home) capacity = 271581184 (259.0MB) used = 212289648 (202.45518493652344MB) free = 59291536 (56.54481506347656MB) 78.16802507201677% used 33603 interned Strings occupying 3737888 bytes.
jmap -histo 7807 | head -30
num #instances #bytes class name ---------------------------------------------- 1: 346185 117868872 [B 2: 603520 64592800 [C 3: 145217 13940832 java.util.jar.JarFile JarFileEntry 4: 578985 13895640 java.lang.String 5: 126460 13392344 [I 6: 200368 8014720 java.util.TreeMap $ Entry 7: 247294 7913408 java.util.HashMap $ Node 8: 118956 4758240 java.util.HashMap$KeyIterator 9: 21730 3842512 [Ljava.util.HashMap $ Node; 10: 100798 3225536 java.io.File 11: 76437 3057480 java.util.HashMap$ValueIterator 12: 39387 2372408 [Ljava.lang.Object; 13: 32109 2054976 java.net.URL 14: 28289 2036808 java.util.regex.Pattern 15: 76439 1834536 org.apache.catalina.LifecycleEvent 16: 62955 1814072 [Ljava.lang.String; 17: 28177 1803328 java.util.regex.Matcher 18: 14724 1665208 java.lang.Class 19: 28161 1577016 [Ljava.util.regex.Pattern$GroupHead; 20: 17892 1574496 java.lang.reflect.Method 21: 76439 1534144 [Lorg.apache.catalina.Container; 22: 30096 1444608 java.util.HashMap 23: 26811 1072440 java.util.LinkedHashMap$Entry 24: 31914 1021248 java.util.concurrent.ConcurrentHashMap$Node 25: 19139 918672 org.apache.catalina.loader.ResourceEntry 26: 35760 858240 java.util.ArrayList 27: 13861 776216 java.util.concurrent.ConcurrentHashMap$ValueIterator
java type descriptor:
refer to: http://blog.csdn.net/qinjuning/article/details/7599796
jmap -dump:live,format=b,file=/home/temp.hprof 7807 Dumping heap to /home/soft/0503.hprof ... file size limit
After all, jmap is a command tool, which is too abstract. You can use the visualvm graphical interface that comes with jdk to view it!
C:\Program Files\Java\jdk1.7.0_71\bin\jvisualvm.exe