MAT内存分析之OQL
所属分类 MAT
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Memory Analyzer allows to query the heap dump with custom SQL-like queries.
OQL represents classes as tables, objects as rows, and fields as columns.
Object Query Language
SELECT *
FROM [ INSTANCEOF ] $classname [ WHERE $filter-expression ]
不同的ClassLoader载入同样名字的类是不同的类型
instanceof 含子类
obj.fieldName 访问字段, array[index] 访问数组元素
select * from "java.lang.*"
SELECT * FROM java.lang.String
选中对象 (可多个)右键 copy / OQL query
SELECT * FROM OBJECTS 7135,7130
SELECT * FROM java.lang.String s WHERE s.value.@length > 100
SELECT * FROM java.lang.String s where toString(s) = "execute"
SELECT * FROM java.lang.String s where s.@retainedHeapSize >1000
SELECT * FROM int[] a where a.@length > 10
select * from java.lang.Thread
SELECT * FROM INSTANCEOF java.lang.Thread a WHERE toString(a.name) = "main"
SELECT * FROM java.lang.Thread a WHERE toString(a.name) = "main"
SELECT * FROM java.lang.Thread a WHERE (toString(a.name) like "ma.*")
注意 和 like 和 sql的区别
SELECT * FROM OBJECTS java.lang.String
java.lang.String对应的Class
属性访问器
alias.field.field
对象字段
alias@attribute
属性
objectId 快照中对象的ID
objectAddress 快照中对象的地址
usedHeapSize 对象的shallowSize
retainedHeapSize 对象的retainedSize
displayName 对象的显示名称
length 数组的长度
SELECT a.@objectId,a.@objectAddress,a.@usedHeapSize,a.@retainedHeapSize,a.@displayName,a.@class,a.@clazz FROM java.lang.String a
SELECT toString(a.value) FROM java.lang.String a
SELECT * FROM instanceof java.util.List
无结果
SELECT * FROM java.util.ArrayList
SELECT * FROM instanceof java.util.ArrayList
SELECT * FROM "java.util.*List"
SELECT * FROM instanceof "java.util.*List"
SELECT * FROM byte[]
SELECT * FROM byte[] a where a.@length > 100000
SELECT s FROM java.lang.String s WHERE s.value.@length >= 10000
SELECT * FROM 0x2b7468c8,0x2b74aee0
SELECT * FROM 20815,20975
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