plugins/org.eclipse.mat.ui.help/reference/inspections/merge_shortest_paths.html - mat/org.eclipse.mat - Git at Google

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 <meta name="DC.title" content="Merge Shortest Paths" />
 <meta name="abstract" content="Find out who is keeping alive a set of objects." />
 <meta name="description" content="Find out who is keeping alive a set of objects." />
 <meta name="copyright" content="Copyright (c) 2020, 2023 IBM Corporation. All rights reserved. This program and the accompanying materials are made available under the terms of the Eclipse Public License 2.0 which accompanies this distribution, and is available at https://www.eclipse.org/legal/epl-2.0/ " type="primary" />
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 <title>Merge Shortest Paths</title>
 </head>
 <body id="ref_inspections_path_to_gc_roots">

 	<h1 class="title topictitle1" id="ariaid-title1">Merge Shortest Paths</h1>


 	<div class="body refbody"><p class="shortdesc">Find out who is keeping alive a set of objects.
 	</p>

 		<div class="section"><h2 class="title sectiontitle">Motivation</h2>

 			<p class="p">Having found an expensive object it is then important to find all
 				the reasons it is kept alive.
 			</p>

 		</div>

 		<div class="section"><h2 class="title sectiontitle">Explanation</h2>

 			<p class="p">
 				Unlike the
 				<a class="xref" href="path_to_gc_roots.html" title="Find out who is keeping alive a single object.">Path to GC roots</a>
 				query, this query
 				can operate on multiple objects.
 				However, it only
 				finds the shortest path to GC roots; there may
 				be other paths, but
 				this query does not show them.
 				As it operates on multiple objects
 				there are multiple paths,
 				and the query has the option to merge
 				objects on a path by
 				class.
 				Seeing a common path can be useful in
 				understanding why a
 				set of objects is being kept alive.
 			</p>

 		</div>

 		<div class="section"><h2 class="title sectiontitle">Arguments</h2>

 			<table cellpadding="4" cellspacing="0" summary="" border="1" class="simpletable"><col style="width:50%" /><col style="width:50%" /><thead><tr class="sthead">
 					<th style="vertical-align:bottom;text-align:left;" id="d10637e63" class="stentry">Argument</th>

 					<th style="vertical-align:bottom;text-align:left;" id="d10637e66" class="stentry">Description</th>

 				</tr>
 </thead><tbody><tr class="strow">
 					<td style="vertical-align:top;" headers="d10637e63" class="stentry">objects</td>

 					<td style="vertical-align:top;" headers="d10637e66" class="stentry">Objects for which paths to garbage collection roots should
 						be
 						found.
 					</td>

 				</tr>
 <tr class="strow">
 					<td style="vertical-align:top;" headers="d10637e63" class="stentry">
 						<span class="keyword parmname">-excludes</span>
 					</td>

 					<td style="vertical-align:top;" headers="d10637e66" class="stentry">
 						Fields of certain classes which should be ignored when finding
 						paths. For example this allows paths through Weak or Soft
 						Reference referents to be ignored.
 						This is of the format
 						<var class="keyword varname">class name pattern</var>
 						[:
 						<var class="keyword varname">field name</var>
 						[,
 						<var class="keyword varname">field name</var>
 						]*].
 						Subclasses of the class are also included.
 						If no field names
 						are specified for the class then all fields are
 						excluded.
 					</td>

 				</tr>
 <tr class="strow">
 					<td style="vertical-align:top;" headers="d10637e63" class="stentry">
 						<span class="keyword parmname">-groupby</span>
 					</td>

 					<td style="vertical-align:top;" headers="d10637e66" class="stentry">
 						Whether to show:
 						<ul class="ul">
 							<li class="li">
 								<span class="keyword parmname">Merge Paths from GC Roots</span>
 								merged paths from garbage collection roots to the objects
 							</li>

 							<li class="li">
 								<span class="keyword parmname">Merge Paths from GC Roots on Class</span>
 								merged paths from garbage collection roots to the objects
 								grouped by class, so all objects of the same class are shown as
 								one
 							</li>

 							<li class="li">
 								<span class="keyword parmname">Merge to GC Roots on Class</span>
 								merged paths from the objects to garbage collection roots
 								grouped
 								by class, so all objects of the same class are shown as
 								one
 							</li>

 						</ul>

 					</td>

 				</tr>
 </tbody></table>

 		</div>

 		<div class="section" id="ref_inspections_path_to_gc_roots__result"><h2 class="title sectiontitle">Result</h2>

 			<p class="p">
 				The tree shows objects or sets of objects grouped by class on a path
 				to or from GC roots.
 				The
 				<span class="keyword wintitle">Referenced Objects</span>
 				column shows how many
 				of the objects supplied to this query are on a path through this
 				row.
 			</p>

 			<p class="p">The context menu allows the objects on this segment of the path,
 				or the referenced objects through this path to be separately
 				examined with other queries.
 			</p>

 			<span class="keyword wintitle">Merge shortest paths from GC roots</span>
 			<img class="image" src="../../mimes/merge_shortest_paths1.png" height="393" width="768" alt="Result of a merge shortest paths query, showing a tree view starting from GC roots." />
 			<div class="note"><span class="notetitle">Note:</span>
 				With
 				<span class="keyword parmname">Merge Paths from GC Roots</span>
 				and
 				<span class="keyword parmname">Merge from GC Roots on Class</span>
 				the arrows in each
 				<a class="xref" href="../iconassist.html">
 					<img class="image" src="../../mimes/i-horefbelow.png" alt="Icon of a piece of paper with an arrow at the bottom right pointing down and to the right." />
 					icon
 				</a>
 				points down and to the right, showing
 				that the objects or objects of
 				a line refer via the field in
 				<strong class="ph b">bold</strong>
 				to the following object or objects in
 				the tree view which is down and
 				to the right.
 				The
 				<span class="keyword parmname">Merge from GC Roots on Class</span>
 				does
 				not show field names as different objects may refer to
 				the
 				following objects by different fields.
 			</div>

 			<span class="keyword wintitle">Merge shortest paths from GC roots on class</span>
 			<img class="image" src="../../mimes/merge_shortest_paths2.png" height="418" width="675" alt="Result of a merge shortest paths query, showing a tree view starting from GC roots, but merged on classes." />
 			<div class="note"><span class="notetitle">Note:</span> See the menu option to switch between the different <span class="keyword parmname">groupby</span>
 				options.</div>

 			<span class="keyword wintitle">Merge shortest paths to GC roots on class</span>
 			<img class="image" src="../../mimes/merge_shortest_paths3.png" height="393" width="579" alt="Result of a merge shortest paths query, showing a tree view starting from the objects, merged on classes, going to GC roots." />
 			<div class="note"><span class="notetitle">Note:</span>
 				With
 				<span class="keyword parmname">Merge to GC Roots on Class</span>
 				the arrows in each
 				<a class="xref" href="../iconassist.html">
 					<img class="image" src="../../mimes/i-horefabove.png" alt="Icon of a piece of paper with an arrow at the top left pointing up and to the left." />
 					icon
 				</a>
 				points up and to the left, showing
 				that the object or objects of a
 				line actually refer
 				to the preceding objects in
 				the tree view which is
 				up and to the left.
 			</div>

 		</div>

 	</div>

 </body>
 </html>
	<?xml version="1.0" encoding="UTF-8"?>
	<!DOCTYPE html
	PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
	<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-us" lang="en-us">
	<head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />

	<meta name="generator" content="DITA-OT" /><meta name="DC.type" content="reference" />
	<meta name="DC.title" content="Merge Shortest Paths" />
	<meta name="abstract" content="Find out who is keeping alive a set of objects." />
	<meta name="description" content="Find out who is keeping alive a set of objects." />
	<meta name="copyright" content="Copyright (c) 2020, 2023 IBM Corporation. All rights reserved. This program and the accompanying materials are made available under the terms of the Eclipse Public License 2.0 which accompanies this distribution, and is available at https://www.eclipse.org/legal/epl-2.0/ " type="primary" />
	<meta name="DC.rights.owner" content="Copyright (c) 2020, 2023 IBM Corporation. All rights reserved. This program and the accompanying materials are made available under the terms of the Eclipse Public License 2.0 which accompanies this distribution, and is available at https://www.eclipse.org/legal/epl-2.0/ " type="primary" />
	<meta name="DC.format" content="XHTML" />
	<meta name="DC.identifier" content="ref_inspections_path_to_gc_roots" />
	<meta name="DC.language" content="en-us" />
	<link rel="stylesheet" type="text/css" href="../../styles/commonltr.css" />
	<title>Merge Shortest Paths</title>
	</head>
	<body id="ref_inspections_path_to_gc_roots">

	<h1 class="title topictitle1" id="ariaid-title1">Merge Shortest Paths</h1>




	<div class="body refbody"><p class="shortdesc">Find out who is keeping alive a set of objects.
	</p>

	<div class="section"><h2 class="title sectiontitle">Motivation</h2>

	<p class="p">Having found an expensive object it is then important to find all
	the reasons it is kept alive.
	</p>

	</div>

	<div class="section"><h2 class="title sectiontitle">Explanation</h2>

	<p class="p">
	Unlike the
	<a class="xref" href="path_to_gc_roots.html" title="Find out who is keeping alive a single object.">Path to GC roots</a>
	query, this query
	can operate on multiple objects.
	However, it only
	finds the shortest path to GC roots; there may
	be other paths, but
	this query does not show them.
	As it operates on multiple objects
	there are multiple paths,
	and the query has the option to merge
	objects on a path by
	class.
	Seeing a common path can be useful in
	understanding why a
	set of objects is being kept alive.
	</p>

	</div>

	<div class="section"><h2 class="title sectiontitle">Arguments</h2>

	<table cellpadding="4" cellspacing="0" summary="" border="1" class="simpletable"><col style="width:50%" /><col style="width:50%" /><thead><tr class="sthead">
	<th style="vertical-align:bottom;text-align:left;" id="d10637e63" class="stentry">Argument</th>

	<th style="vertical-align:bottom;text-align:left;" id="d10637e66" class="stentry">Description</th>

	</tr>
	</thead><tbody><tr class="strow">
	<td style="vertical-align:top;" headers="d10637e63" class="stentry">objects</td>

	<td style="vertical-align:top;" headers="d10637e66" class="stentry">Objects for which paths to garbage collection roots should
	be
	found.
	</td>

	</tr>
	<tr class="strow">
	<td style="vertical-align:top;" headers="d10637e63" class="stentry">
	<span class="keyword parmname">-excludes</span>
	</td>

	<td style="vertical-align:top;" headers="d10637e66" class="stentry">
	Fields of certain classes which should be ignored when finding
	paths. For example this allows paths through Weak or Soft
	Reference referents to be ignored.
	This is of the format
	<var class="keyword varname">class name pattern</var>
	[:
	<var class="keyword varname">field name</var>
	[,
	<var class="keyword varname">field name</var>
	]*].
	Subclasses of the class are also included.
	If no field names
	are specified for the class then all fields are
	excluded.
	</td>

	</tr>
	<tr class="strow">
	<td style="vertical-align:top;" headers="d10637e63" class="stentry">
	<span class="keyword parmname">-groupby</span>
	</td>

	<td style="vertical-align:top;" headers="d10637e66" class="stentry">
	Whether to show:
	<ul class="ul">
	<li class="li">
	<span class="keyword parmname">Merge Paths from GC Roots</span>
	merged paths from garbage collection roots to the objects
	</li>

	<li class="li">
	<span class="keyword parmname">Merge Paths from GC Roots on Class</span>
	merged paths from garbage collection roots to the objects
	grouped by class, so all objects of the same class are shown as
	one
	</li>

	<li class="li">
	<span class="keyword parmname">Merge to GC Roots on Class</span>
	merged paths from the objects to garbage collection roots
	grouped
	by class, so all objects of the same class are shown as
	one
	</li>

	</ul>

	</td>

	</tr>
	</tbody></table>

	</div>

	<div class="section" id="ref_inspections_path_to_gc_roots__result"><h2 class="title sectiontitle">Result</h2>

	<p class="p">
	The tree shows objects or sets of objects grouped by class on a path
	to or from GC roots.
	The
	<span class="keyword wintitle">Referenced Objects</span>
	column shows how many
	of the objects supplied to this query are on a path through this
	row.
	</p>

	<p class="p">The context menu allows the objects on this segment of the path,
	or the referenced objects through this path to be separately
	examined with other queries.
	</p>

	<span class="keyword wintitle">Merge shortest paths from GC roots</span>
	<img class="image" src="../../mimes/merge_shortest_paths1.png" height="393" width="768" alt="Result of a merge shortest paths query, showing a tree view starting from GC roots." />
	<div class="note"><span class="notetitle">Note:</span>
	With
	<span class="keyword parmname">Merge Paths from GC Roots</span>
	and
	<span class="keyword parmname">Merge from GC Roots on Class</span>
	the arrows in each
	<a class="xref" href="../iconassist.html">
	<img class="image" src="../../mimes/i-horefbelow.png" alt="Icon of a piece of paper with an arrow at the bottom right pointing down and to the right." />
	icon
	</a>
	points down and to the right, showing
	that the objects or objects of
	a line refer via the field in
	<strong class="ph b">bold</strong>
	to the following object or objects in
	the tree view which is down and
	to the right.
	The
	<span class="keyword parmname">Merge from GC Roots on Class</span>
	does
	not show field names as different objects may refer to
	the
	following objects by different fields.
	</div>

	<span class="keyword wintitle">Merge shortest paths from GC roots on class</span>
	<img class="image" src="../../mimes/merge_shortest_paths2.png" height="418" width="675" alt="Result of a merge shortest paths query, showing a tree view starting from GC roots, but merged on classes." />
	<div class="note"><span class="notetitle">Note:</span> See the menu option to switch between the different <span class="keyword parmname">groupby</span>
	options.</div>

	<span class="keyword wintitle">Merge shortest paths to GC roots on class</span>
	<img class="image" src="../../mimes/merge_shortest_paths3.png" height="393" width="579" alt="Result of a merge shortest paths query, showing a tree view starting from the objects, merged on classes, going to GC roots." />
	<div class="note"><span class="notetitle">Note:</span>
	With
	<span class="keyword parmname">Merge to GC Roots on Class</span>
	the arrows in each
	<a class="xref" href="../iconassist.html">
	<img class="image" src="../../mimes/i-horefabove.png" alt="Icon of a piece of paper with an arrow at the top left pointing up and to the left." />
	icon
	</a>
	points up and to the left, showing
	that the object or objects of a
	line actually refer
	to the preceding objects in
	the tree view which is
	up and to the left.
	</div>

	</div>

	</div>

	</body>
	</html>