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How to print memory usage of Java objects

In the next question: Possible Spring Boot or Spring Memory Leak Leak

The user prints java objects as follows:

 num     #instances         #bytes  class name
----------------------------------------------
   1:        395984       32564344  [C
   2:        388697        9328728  java.lang.String
   3:         61258        5915088  [B
   4:        100297        4814256  java.util.HashMap
   5:         50892        4478496  org.apache.catalina.session.StandardSession
   6:         58774        3656824  [Ljava.util.HashMap$Node;
   7:         84773        3390920  java.util.TreeMap$Entry
   8:         51522        3339304  [Ljava.util.Hashtable$Entry;
   9:         51834        3317376  java.util.concurrent.ConcurrentHashMap
  10:        102111        3267552  java.util.HashMap$Node
  11:         96256        3080192  java.util.concurrent.ConcurrentHashMap$Node
  12:         24101        2754560  [Ljava.util.concurrent.ConcurrentHashMap$Node;
  13:         51472        2470656  java.util.Hashtable
  14:         55102        2204080  java.util.LinkedHashMap$Entry
  15:         83020        1992480  java.util.ArrayList
  16:         34353        1923768  java.util.LinkedHashMap
  17:         59156        1892992  org.springframework.boot.loader.util.AsciiBytes
  18:         29574        1656144  org.springframework.boot.loader.jar.JarEntryData
  19:         18029        1586552  java.lang.reflect.Method
  20:         28391        1562080  [Ljava.lang.Object;
  21:         37178        1487120  java.lang.ref.SoftReference
  22:         47648        1446600  [I
  23:         52337        1256088  java.lang.Long
  24:         26134        1254432  java.util.TreeMap
  25:         50904        1221696  java.beans.PropertyChangeSupport
  26:         11777        1214464  java.lang.Class
  27:         23748        1139904  org.springframework.security.oauth2.provider.OAuth2Request
  28:         35994         863856  java.util.Collections$UnmodifiableRandomAccessList
  29:         50904         814464  java.beans.PropertyChangeSupport$PropertyChangeListenerMap
  30:         50892         814272  org.apache.catalina.session.StandardSessionFacade
  31:         49748         795968  java.util.HashSet
  32:         24066         770112  java.util.Collections$UnmodifiableMap
  33:         23748         759936  org.springframework.security.oauth2.provider.OAuth2Authentication
  34:         23748         759936  org.springframework.security.oauth2.provider.authentication.OAuth2AuthenticationDetails
  35:         26000         624000  javax.management.openmbean.CompositeDataSupport
  36:         12015         576664  [Ljava.lang.String;
  37:         16319         522208  com.sun.org.apache.xerces.internal.xni.QName
  38:         15288         489216  java.lang.ref.WeakReference
  39:         26448         423168  java.util.LinkedHashSet
  40:         26011         416176  java.util.TreeMap$KeySet

What command did the user use to print this information?

Btw, I added the following arguments to my Java process.

-XX:+PrintGCDetails -XX:+PrintGCTimeStamps -Xloggc:gc.log -verbose:gc

I hope I correctly formulated the question.

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3 answers

This is the result of jmap -histo. Maybe jmap -histo:live. You run it as an external tool and supply the pid JVM. It is provided in binyour jdk installation directory.

, , jmap -histo:live GC, , . jmap -histo GC.

jmap documentation

+4

, :

java -agentlib:hprof=heap=sites <Your program>

Oracle/SUN HPROF

, , .

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