Tracking Memory Leaks - Revision history

imported>Mathieu: Category:Developer documentation

2008-11-10T11:03:02Z

← Older revision		Revision as of 11:03, 10 November 2008
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	The online help of the tool is very well done and gives various strategies for analysing the allocated memory at the time of the dump.		The online help of the tool is very well done and gives various strategies for analysing the allocated memory at the time of the dump.


			[[Category:Developer documentation]]

imported>Mathieu: typo

2008-11-10T10:56:43Z

typo

← Older revision		Revision as of 10:56, 10 November 2008
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	It can happen that a plug-in consumes a lot of memory, and, worse, never		It can happen that a plug-in consumes a lot of memory, and, worse, never releases it. This recently happened to the new Predicate Prover
	releases it. This recently happened to the new Predicate Prover		plug-in. While looking for a proof, it was allocating megabytes of memory, and upon cancellation the memory was not garbage collected. This
	plug-in. While looking for a proof, it was allocating megabytes of		impeded seriously proving, as attempting to use this prover was allocating memory that was never freed. Users then had to manually
	memory, and upon cancellation the memory was not garbage collected. This		restart the platform every third or fourth attempt of using this prover.
	impeded seriously proving, as attempting to use this prover was
	allocating memory that was never freed. Users then had to manually
	restart the platform every third or fourth attempt of using this prover.

	This document explains how such memory leaks can be examined and how one		This document explains how such memory leaks can be examined and how one can trace their origin using simple useful tools. The proposed method
	can trace their origin using simple useful tools. The proposed method		consists in using the JVM heap dump feature, together with an external tool for inquiring into a heap dump.
	consists in using the JVM heap dump feature, together with an external
	tool for inquiring into a heap dump.

	==Producing a Heap Dump==		==Producing a Heap Dump==

	This document supposes that the standard JVM from Sun (or the one		This document supposes that the standard JVM from Sun (or the one bundled with Mac OS X) is used.
	bundled with Mac OS X) is used.

	To produce a heap dump, add the following VM argument to the command		To produce a heap dump, add the following VM argument to the command used to launch the platform (e.g., in the {{menu\|Arguments}} tab of the {{menu\|Run}} dialog of Eclipse):
	used to launch the platform (e.g., in the {{menu\|Arguments}} tab of the
	{{menu\|Run}} dialog of Eclipse):
	<pre>		<pre>
	-Xrunhprof:format=b,file=/tmp/xx.hprof		-Xrunhprof:format=b,file=/tmp/xx.hprof
	</pre>		</pre>

	When given this argument, he JVM will write in the specified file (here		When given this argument, he JVM will write in the specified file (here {{file\|/tmp/xx.hprof}}) a copy of the heap upon program termination. It is also possible to force a heap dump while the application is running by sending a QUIT signal (number 3) to the JVM while it is running (I don't know how to do that on Windows platforms).
	{{file\|/tmp/xx.hprof}}) a copy of the heap upon program termination. It is
	also possible to force a heap dump while the application is running by
	sending a QUIT signal (number 3) to the JVM while it is running (I don't
	know how to do that on Windows platforms).

	==Analysing a Heap Dump==		==Analysing a Heap Dump==

	With the Java 6 JDK, there is a bundled tool called {{ident\|jhat}} that allows		With the Java 6 JDK, there is a bundled tool called {{ident\|jhat}} that allows to analyse a heap dump. However, SAP developed another tool based on
	to analyse a heap dump. However, SAP developed another tool based on		Eclipse which is more user-friendly and easy to use. This tool is available from (free registration required):
	Eclipse which is more user-friendly and easy to use. This tool is
	available from (free registration required):

	https://www.sdn.sap.com/irj/sdn/wiki?path=/display/Java/Java+Memory+Analysis		https://www.sdn.sap.com/irj/sdn/wiki?path=/display/Java/Java+Memory+Analysis

	The online help of the tool is very well done and gives various strategies		The online help of the tool is very well done and gives various strategies for analysing the allocated memory at the time of the dump.
	for analysing the allocated memory at the time of the dump.

imported>Mathieu: Imported from http://rodin-b-sharp.wiki.sourceforge.net/Tracking+Memory+Leaks

2008-11-10T10:55:23Z

Imported from http://rodin-b-sharp.wiki.sourceforge.net/Tracking+Memory+Leaks

New page

It can happen that a plug-in consumes a lot of memory, and, worse, never
releases it. This recently happened to the new Predicate Prover
plug-in. While looking for a proof, it was allocating megabytes of
memory, and upon cancellation the memory was not garbage collected. This
impeded seriously proving, as attempting to use this prover was
allocating memory that was never freed. Users then had to manually
restart the platform every third or fourth attempt of using this prover.

This document explains how such memory leaks can be examined and how one
can trace their origin using simple useful tools. The proposed method
consists in using the JVM heap dump feature, together with an external
tool for inquiring into a heap dump.

==Producing a Heap Dump==

This document supposes that the standard JVM from Sun (or the one
bundled with Mac OS X) is used.

To produce a heap dump, add the following VM argument to the command
used to launch the platform (e.g., in the {{menu|Arguments}} tab of the
{{menu|Run}} dialog of Eclipse):
<pre>
-Xrunhprof:format=b,file=/tmp/xx.hprof
</pre>

When given this argument, he JVM will write in the specified file (here
{{file|/tmp/xx.hprof}}) a copy of the heap upon program termination. It is
also possible to force a heap dump while the application is running by
sending a QUIT signal (number 3) to the JVM while it is running (I don't
know how to do that on Windows platforms).

==Analysing a Heap Dump==

With the Java 6 JDK, there is a bundled tool called {{ident|jhat}} that allows
to analyse a heap dump. However, SAP developed another tool based on
Eclipse which is more user-friendly and easy to use. This tool is
available from (free registration required):

https://www.sdn.sap.com/irj/sdn/wiki?path=/display/Java/Java+Memory+Analysis

The online help of the tool is very well done and gives various strategies
for analysing the allocated memory at the time of the dump.