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| <h1 class="title topictitle1" id="ariaid-title1">Dominator Tree</h1> |
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| <div class="body conbody"> |
| <p class="p">Memory Analyzer provides a dominator tree of the object graph. |
| The transformation of the object reference graph into a |
| dominator tree allows you to easily identify the biggest chunks of |
| retained memory and the keep-alive dependencies among objects. |
| Below is an informal definition of the terms.</p> |
| |
| <p class="p"> |
| An object x |
| <strong class="ph b">dominates</strong> |
| an object y if every path in the object graph from the start (or the |
| root) node to y must go through x. |
| </p> |
| |
| <p class="p"> |
| The |
| <strong class="ph b">immediate dominator</strong> |
| x of some object y is the dominator closest to the object y. |
| </p> |
| |
| <p class="p"> |
| A |
| <strong class="ph b">dominator tree</strong> |
| is built out of the object graph. In the dominator tree each object |
| is the immediate dominator of its children, so dependencies between |
| the objects are easily identified. |
| </p> |
| |
| <p class="p">The dominator tree has the following important properties:</p> |
| |
| <ul class="ul"> |
| <li class="li"> |
| The objects belonging to the sub-tree of |
| <span class="keyword">x</span> |
| (i.e. the objects dominated by |
| <span class="keyword">x</span> |
| ) represent the <a class="xref" href="shallowretainedheap.html">retained set</a> of |
| <span class="keyword">x</span> |
| . |
| </li> |
| |
| <li class="li"> |
| If |
| <span class="keyword">x</span> |
| is the immediate dominator of |
| <span class="keyword">y</span> |
| , then the immediate dominator of |
| <span class="keyword">x</span> |
| also dominates |
| <span class="keyword">y</span> |
| , and so on. |
| </li> |
| |
| <li class="li">The edges in the dominator tree do not directly correspond to |
| object references from the object graph.</li> |
| |
| </ul> |
| |
| <img class="image" src="../mimes/m2268b281.png" alt="Object graph transformed to dominator tree" /> |
| |
| </div> |
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| <div class="related-links"> |
| <div class="linklist relinfo relconcepts" xml:lang="en-us" lang="en-us"><strong>Related concepts</strong><br /> |
| <ul class="linklist"> |
| <li class="linklist"><a class="link" href="shallowretainedheap.html">Shallow vs. Retained Size</a></li></ul></div> |
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