jmap -histo 19183 | head -20 

 num     #instances         #bytes  class name ----------------------------------------------    1:        223718      460271832  [I    2:       2125963      273642920  [C    3:        323214      142451944  [B    4:       1498297       35959128  java.lang.String    5:        535649       28576352  [Ljava.lang.Object;    6:        472738       26473328  java.util.LinkedHashMap    7:        632837       20250784  juc.locks.AbstractQueuedSynchronizer$Node    8:        231974       17470032  [Ljava.util.HashMap$Node;    9:        426575       17063000  java.util.LinkedHashMap$Entry   10:        452507       14480224  java.util.LinkedHashMap$LinkedKeyIterator   11:        481794       11563056  java.util.ArrayList   12:        108053        9508664  java.lang.reflect.Method   13:          5536        9187024  [Ljava.util.concurrent.ConcurrentHashMap$Node;   14:        267553        8561696  java.util.ArrayList$Itr   15:        291985        7850920  [Ljava.lang.String;   16:        125609        6029232  java.util.HashMap   17:        165873        5307936  java.util.concurrent.ConcurrentHashMap$Node 

一般来说，String 对象更多一点，也就是 [C 更多才对。。。好奇怪