What is retained heap size?
Retained heap is the amount of memory that will be freed when the particular object is garbage collected. Thus, retained heap size of B is 30 bytes.
What is retained size in heap dump?
1 Answer. The retained size for an object is the quantity of memory this objects preserves from garbage collection. The formal definition is “the size of the object plus the size of all objects referenced only by the first object, recursively”.
What is shallow size and retained size?
Shallow and retained size shallow size: the size of the object itself. retained size: the size of the object itself, plus the size of other objects that are kept alive by this object.
What is shallow heap vs retained heap?
Shallow heap is the memory consumed by one object. Retained set of X is the set of objects which would be removed by GC when X is garbage collected. Retained heap of X is the sum of shallow sizes of all objects in the retained set of X, i.e. memory kept alive by X.
What is shallow heap in heap dump?
In Simple words Shallow heap of an object is its size in the heap and retained size of the same object is the amount of heap memory that will be freed when the object is garbage collected.
What is retained heap Java?
Retained heap is the amount of memory that will be freed when the particular object is garbage collected. Thus, the retained heap size of B is: = B’s shallow heap size + D’s shallow heap size + E’s shallow heap size.
What are GC roots?
The so-called GC (Garbage Collector) roots are objects special for garbage collector. Garbage collector collects those objects that are not GC roots and are not accessible by references from GC roots. There are several kinds of GC roots. They can hold objects via static fields. …
What is distance in heap snapshot?
There is a distance field in the heap snapshots which is the number of property references on the shortest retaining path from the window. Document DOM tree consisting of all native DOM nodes reachable by traversing the document.
What is heap dump analysis?
Heap dumps contain a snapshot of all the live objects that are being used by a running Java application on the Java heap. We can obtain detailed information for each object instance, such as the address, type, class name, or size, and whether the instance has references to other objects.
What is thread dump and heap dump?
A thread dump is a dump of the stacks of all live threads. Thus useful for analysing what an app is up to at some point in time, and if done at intervals handy in diagnosing some kinds of ‘execution’ problems (e.g. thread deadlock). A heap dump is a dump of the state of the Java heap memory.
What is thread dump Java?
A thread dump is a list of all the Java threads that are currently active in a Java Virtual Machine (JVM). There are several ways to take thread dumps from a JVM. A good practice is to take 10 thread dumps at a regular interval (for example, one thread dump every ten seconds).
What is shallow size in heap dump?
Shallow heap is the memory consumed by one object. An object needs 32 or 64 bits (depending on the OS architecture) per reference, 4 bytes per Integer, 8 bytes per Long, etc. Depending on the heap dump format the size may be adjusted (e.g. aligned to 8, etc…) to model better the real consumption of the VM.
What does it mean to have retained heap in Java?
So, if object B is garbage collected from memory, there will be no more active references to object D and E. It means D & E can also be garbage collected. Retained heap is the amount of memory that will be freed when the particular object is garbage collected.
What is the retained heap size of B?
Thus, the retained heap size of B is 30 bytes. Object C is holding a reference to objects F and G. So, if object C is garbage collected from memory, there will be no more references to object F and G. It means F and G can also be garbage collected.
How big is retained heap in Eclipse mat?
The total retained heap size of A will become 40 bytes. All other objects retained heap size will remain undisturbed, because there is no change in their references. Hope this article helped to clarify Shallow heap size and Retained heap size calculation in Eclipse MAT.
What is retained size for an object on heapdump?
1 Answer 1. The retained size for an object is the quantity of memory this objects preserves from garbage collection. The formal definition is “the size of the object plus the size of all objects referenced only by the first object, recursively”. For more explanations about what the retained memory is, see this article.