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Posted to dev@tomcat.apache.org by ma...@apache.org on 2010/02/24 01:07:07 UTC
svn commit: r915603 - in /tomcat/tc6.0.x/trunk: ./
java/org/apache/catalina/core/ java/org/apache/catalina/loader/
java/org/apache/catalina/manager/ webapps/docs/ webapps/manager/WEB-INF/
Author: markt
Date: Wed Feb 24 00:07:06 2010
New Revision: 915603
URL: http://svn.apache.org/viewvc?rev=915603&view=rev
Log:
Add basic memory leak detection for JMX and manager (kkolinko/markt)
Modified:
tomcat/tc6.0.x/trunk/STATUS.txt
tomcat/tc6.0.x/trunk/java/org/apache/catalina/core/StandardHost.java
tomcat/tc6.0.x/trunk/java/org/apache/catalina/core/mbeans-descriptors.xml
tomcat/tc6.0.x/trunk/java/org/apache/catalina/loader/WebappClassLoader.java
tomcat/tc6.0.x/trunk/java/org/apache/catalina/manager/HTMLManagerServlet.java
tomcat/tc6.0.x/trunk/java/org/apache/catalina/manager/LocalStrings.properties
tomcat/tc6.0.x/trunk/java/org/apache/catalina/manager/ManagerServlet.java
tomcat/tc6.0.x/trunk/webapps/docs/changelog.xml
tomcat/tc6.0.x/trunk/webapps/docs/html-manager-howto.xml
tomcat/tc6.0.x/trunk/webapps/docs/manager-howto.xml
tomcat/tc6.0.x/trunk/webapps/manager/WEB-INF/web.xml
Modified: tomcat/tc6.0.x/trunk/STATUS.txt
URL: http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/STATUS.txt?rev=915603&r1=915602&r2=915603&view=diff
==============================================================================
--- tomcat/tc6.0.x/trunk/STATUS.txt (original)
+++ tomcat/tc6.0.x/trunk/STATUS.txt Wed Feb 24 00:07:06 2010
@@ -118,36 +118,6 @@
http://tools.ietf.org/html/rfc2616
-
-* Memory leak detection for JMX and manager
- http://people.apache.org/~kkolinko/patches/2010-02-16_tc6_memory-leak-detection.patch
- It is corrected markt's patch
- (Added revs.909204,910584,910612
- TC 6 specifics: /findleaks should be explicitly mapped in web.xml,
- where TC 7 uses /text/findleaks, and that URL is mentioned in manager-howto.xml)
- +1: kkolinko, fhanik, markt
- -1:
-
- kkolinko: Some further thoughts on naming/messages/documentation
- - It might be not so clear to a newcomer, that to use this functionality you have
- a) Use you application
- b) Reload it
- c) Press the "Find leaks" button
- It does not work without a) and b).
-
- - Saying that application "triggered" a memory leak sounds too harsh for
- me. I think "has" or "suffered" would be better here.
-
- - It is safe to press the "Find leaks" button several times. Besides the
- gc call it just "lists" the contexts that are still present in memory.
- It does not clear its own list.
-
- kkolinko: The display fix for ROOT context (r910612) might be applied to
- StandardHost.findReloadedContextMemoryLeaks() as well. Any comments? If
- results of a JMX call are displayed to humans, I'd be better to have "/"
- instead of an empty string.
-
-
* Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=48371
Take account of comments when working out where to insert generated web.xml
http://people.apache.org/~markt/patches/2010-02-13-bug48371.patch
Modified: tomcat/tc6.0.x/trunk/java/org/apache/catalina/core/StandardHost.java
URL: http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/java/org/apache/catalina/core/StandardHost.java?rev=915603&r1=915602&r2=915603&view=diff
==============================================================================
--- tomcat/tc6.0.x/trunk/java/org/apache/catalina/core/StandardHost.java (original)
+++ tomcat/tc6.0.x/trunk/java/org/apache/catalina/core/StandardHost.java Wed Feb 24 00:07:06 2010
@@ -19,14 +19,23 @@
package org.apache.catalina.core;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.WeakHashMap;
+
import javax.management.MBeanServer;
import javax.management.ObjectName;
import org.apache.catalina.Container;
import org.apache.catalina.Context;
import org.apache.catalina.Host;
+import org.apache.catalina.Lifecycle;
+import org.apache.catalina.LifecycleEvent;
import org.apache.catalina.LifecycleException;
+import org.apache.catalina.LifecycleListener;
import org.apache.catalina.Valve;
+import org.apache.catalina.loader.WebappClassLoader;
import org.apache.catalina.startup.HostConfig;
import org.apache.catalina.valves.ValveBase;
import org.apache.tomcat.util.modeler.Registry;
@@ -164,6 +173,12 @@
*/
private boolean xmlNamespaceAware = false;
+ /**
+ * Track the class loaders for the child web applications so memory leaks
+ * can be detected.
+ */
+ private Map<ClassLoader, String> childClassLoaders =
+ new WeakHashMap<ClassLoader, String>();
// ------------------------------------------------------------- Properties
@@ -520,6 +535,11 @@
*/
public void addChild(Container child) {
+ if (child instanceof Lifecycle) {
+ ((Lifecycle) child).addLifecycleListener(
+ new MemoryLeakTrackingListener());
+ }
+
if (!(child instanceof Context))
throw new IllegalArgumentException
(sm.getString("standardHost.notContext"));
@@ -529,6 +549,49 @@
/**
+ * Used to ensure the regardless of {@link Context} implementation, a record
+ * is kept of the class loader used every time a context starts.
+ */
+ private class MemoryLeakTrackingListener implements LifecycleListener {
+
+ public void lifecycleEvent(LifecycleEvent event) {
+ if (event.getType().equals(Lifecycle.AFTER_START_EVENT)) {
+ if (event.getSource() instanceof Context) {
+ Context context = ((Context) event.getSource());
+ childClassLoaders.put(context.getLoader().getClassLoader(),
+ context.getServletContext().getContextPath());
+ }
+ }
+ }
+ }
+
+
+ /**
+ * Attempt to identify the contexts that have a class loader memory leak.
+ * This is usually triggered on context reload. Note: This method attempts
+ * to force a full garbage collection. This should be used with extreme
+ * caution on a production system.
+ */
+ public String[] findReloadedContextMemoryLeaks() {
+
+ System.gc();
+
+ List<String> result = new ArrayList<String>();
+
+ for (Map.Entry<ClassLoader, String> entry :
+ childClassLoaders.entrySet()) {
+ ClassLoader cl = entry.getKey();
+ if (cl instanceof WebappClassLoader) {
+ if (!((WebappClassLoader) cl).isStarted()) {
+ result.add(entry.getValue());
+ }
+ }
+ }
+
+ return result.toArray(new String[result.size()]);
+ }
+
+ /**
* Return the set of alias names for this Host. If none are defined,
* a zero length array is returned.
*/
Modified: tomcat/tc6.0.x/trunk/java/org/apache/catalina/core/mbeans-descriptors.xml
URL: http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/java/org/apache/catalina/core/mbeans-descriptors.xml?rev=915603&r1=915602&r2=915603&view=diff
==============================================================================
--- tomcat/tc6.0.x/trunk/java/org/apache/catalina/core/mbeans-descriptors.xml (original)
+++ tomcat/tc6.0.x/trunk/java/org/apache/catalina/core/mbeans-descriptors.xml Wed Feb 24 00:07:06 2010
@@ -542,6 +542,12 @@
<operation name="stop" description="Stop" impact="ACTION" returnType="void" />
<operation name="init" description="Init" impact="ACTION" returnType="void" />
<operation name="destroy" description="Destroy" impact="ACTION" returnType="void" />
+
+ <operation name="findReloadedContextMemoryLeaks"
+ description="Provide a list of contexts that have leaked memory on reload. This will attempt to force a full garbage collection. Use with extreme caution on production systems."
+ impact="ACTION"
+ returnType="[Ljava.lang.String;" />
+
</mbean>
<mbean name="StandardHostValve"
Modified: tomcat/tc6.0.x/trunk/java/org/apache/catalina/loader/WebappClassLoader.java
URL: http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/java/org/apache/catalina/loader/WebappClassLoader.java?rev=915603&r1=915602&r2=915603&view=diff
==============================================================================
--- tomcat/tc6.0.x/trunk/java/org/apache/catalina/loader/WebappClassLoader.java (original)
+++ tomcat/tc6.0.x/trunk/java/org/apache/catalina/loader/WebappClassLoader.java Wed Feb 24 00:07:06 2010
@@ -1642,6 +1642,10 @@
}
+ public boolean isStarted() {
+ return started;
+ }
+
/**
* Stop the class loader.
*
Modified: tomcat/tc6.0.x/trunk/java/org/apache/catalina/manager/HTMLManagerServlet.java
URL: http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/java/org/apache/catalina/manager/HTMLManagerServlet.java?rev=915603&r1=915602&r2=915603&view=diff
==============================================================================
--- tomcat/tc6.0.x/trunk/java/org/apache/catalina/manager/HTMLManagerServlet.java (original)
+++ tomcat/tc6.0.x/trunk/java/org/apache/catalina/manager/HTMLManagerServlet.java Wed Feb 24 00:07:06 2010
@@ -136,6 +136,8 @@
message = start(path);
} else if (command.equals("/stop")) {
message = stop(path);
+ } else if (command.equals("/findleaks")) {
+ message = findleaks();
} else {
message =
sm.getString("managerServlet.unknownCommand", command);
@@ -498,6 +500,16 @@
args[3] = sm.getString("htmlManagerServlet.deployButton");
writer.print(MessageFormat.format(UPLOAD_SECTION, args));
+ // Diagnostics section
+ args = new Object[5];
+ args[0] = sm.getString("htmlManagerServlet.diagnosticsTitle");
+ args[1] = sm.getString("htmlManagerServlet.diagnosticsLeak");
+ args[2] = response.encodeURL(request.getContextPath() +
+ "/html/findleaks");
+ args[3] = sm.getString("htmlManagerServlet.diagnosticsLeakWarning");
+ args[4] = sm.getString("htmlManagerServlet.diagnosticsLeakButton");
+ writer.print(MessageFormat.format(DIAGNOSTICS_SECTION, args));
+
// Server Header Section
args = new Object[7];
args[0] = sm.getString("htmlManagerServlet.serverTitle");
@@ -631,6 +643,33 @@
return stringWriter.toString();
}
+
+ /**
+ * Find potential memory leaks caused by web application reload.
+ *
+ * @see ManagerServlet#findleaks(PrintWriter)
+ *
+ * @return message String
+ */
+ protected String findleaks() {
+
+ StringBuilder msg = new StringBuilder();
+
+ StringWriter stringWriter = new StringWriter();
+ PrintWriter printWriter = new PrintWriter(stringWriter);
+
+ super.findleaks(printWriter);
+
+ if (stringWriter.getBuffer().length() > 0) {
+ msg.append(sm.getString("htmlManagerServlet.findleaksList"));
+ msg.append(stringWriter.toString());
+ } else {
+ msg.append(sm.getString("htmlManagerServlet.findleaksNone"));
+ }
+
+ return msg.toString();
+ }
+
/**
* @see javax.servlet.Servlet#getServletInfo()
@@ -1136,4 +1175,31 @@
"<br>\n" +
"\n";
+ private static final String DIAGNOSTICS_SECTION =
+ "<table border=\"1\" cellspacing=\"0\" cellpadding=\"3\">\n" +
+ "<tr>\n" +
+ " <td colspan=\"2\" class=\"title\">{0}</td>\n" +
+ "</tr>\n" +
+ "<tr>\n" +
+ " <td colspan=\"2\" class=\"header-left\"><small>{1}</small></td>\n" +
+ "</tr>\n" +
+ "<tr>\n" +
+ " <td colspan=\"2\">\n" +
+ "<form method=\"post\" action=\"{2}\">\n" +
+ "<table cellspacing=\"0\" cellpadding=\"3\">\n" +
+ "<tr>\n" +
+ " <td class=\"row-left\">\n" +
+ " <input type=\"submit\" value=\"{4}\">\n" +
+ " </td>\n" +
+ " <td class=\"row-left\">\n" +
+ " <small>{3}</small>\n" +
+ " </td>\n" +
+ "</tr>\n" +
+ "</table>\n" +
+ "</form>\n" +
+ "</td>\n" +
+ "</tr>\n" +
+ "</table>\n" +
+ "<br>";
+
}
Modified: tomcat/tc6.0.x/trunk/java/org/apache/catalina/manager/LocalStrings.properties
URL: http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/java/org/apache/catalina/manager/LocalStrings.properties?rev=915603&r1=915602&r2=915603&view=diff
==============================================================================
--- tomcat/tc6.0.x/trunk/java/org/apache/catalina/manager/LocalStrings.properties (original)
+++ tomcat/tc6.0.x/trunk/java/org/apache/catalina/manager/LocalStrings.properties Wed Feb 24 00:07:06 2010
@@ -43,6 +43,12 @@
htmlManagerServlet.deployUploadNoFile=FAIL - File upload failed, no file
htmlManagerServlet.deployUploadWarExists=FAIL - War file \"{0}\" already exists on server
htmlManagerServlet.deployWar=WAR or Directory URL:
+htmlManagerServlet.diagnosticsLeak=Check to see if a web application has caused a memory leak on reload
+htmlManagerServlet.diagnosticsLeakButton=Find leaks
+htmlManagerServlet.diagnosticsLeakWarning=This diagnostic check will trigger a full garbage collection. Use it with extreme caution on production systems.
+htmlManagerServlet.diagnosticsTitle=Diagnostics
+htmlManagerServlet.findleaksList=The following web applications appear to have triggered a memory leak on reload (use a profiler to confirm):\n
+htmlManagerServlet.findleaksNone=No web applications appear to have triggered a memory leak on reload.
htmlManagerServlet.list=List Applications
htmlManagerServlet.manager=Manager
htmlManagerServlet.messageLabel=Message:
@@ -63,6 +69,7 @@
managerServlet.deployFailed=FAIL - Failed to deploy application at context path {0}
managerServlet.deployedButNotStarted=FAIL - Deployed application at context path {0} but context failed to start
managerServlet.exception=FAIL - Encountered exception {0}
+managerServlet.findleaksFail=FAIL - Find leaks failed: Host not instance of StandardHost
managerServlet.invalidPath=FAIL - Invalid context path {0} was specified
managerServlet.invalidWar=FAIL - Invalid application URL {0} was specified
managerServlet.listed=OK - Listed applications for virtual host {0}
Modified: tomcat/tc6.0.x/trunk/java/org/apache/catalina/manager/ManagerServlet.java
URL: http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/java/org/apache/catalina/manager/ManagerServlet.java?rev=915603&r1=915602&r2=915603&view=diff
==============================================================================
--- tomcat/tc6.0.x/trunk/java/org/apache/catalina/manager/ManagerServlet.java (original)
+++ tomcat/tc6.0.x/trunk/java/org/apache/catalina/manager/ManagerServlet.java Wed Feb 24 00:07:06 2010
@@ -54,6 +54,7 @@
import org.apache.catalina.Session;
import org.apache.catalina.UserDatabase;
import org.apache.catalina.Wrapper;
+import org.apache.catalina.core.StandardHost;
import org.apache.catalina.core.StandardServer;
import org.apache.catalina.util.RequestUtil;
import org.apache.catalina.util.ServerInfo;
@@ -379,6 +380,8 @@
stop(writer, path);
} else if (command.equals("/undeploy")) {
undeploy(writer, path);
+ } else if (command.equals("/findleaks")) {
+ findleaks(writer);
} else {
writer.println(sm.getString("managerServlet.unknownCommand",
command));
@@ -523,6 +526,28 @@
/**
+ * Find potential memory leaks caused by web application reload.
+ */
+ protected void findleaks(PrintWriter writer) {
+
+ if (!(host instanceof StandardHost)) {
+ writer.println(sm.getString("managerServlet.findleaksFail"));
+ return;
+ }
+
+ String[] results =
+ ((StandardHost) host).findReloadedContextMemoryLeaks();
+
+ for (String result : results) {
+ if ("".equals(result)) {
+ result = "/";
+ }
+ writer.println(result);
+ }
+ }
+
+
+ /**
* Store server configuration.
*
* @param path Optional context path to save
Modified: tomcat/tc6.0.x/trunk/webapps/docs/changelog.xml
URL: http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/webapps/docs/changelog.xml?rev=915603&r1=915602&r2=915603&view=diff
==============================================================================
--- tomcat/tc6.0.x/trunk/webapps/docs/changelog.xml (original)
+++ tomcat/tc6.0.x/trunk/webapps/docs/changelog.xml Wed Feb 24 00:07:06 2010
@@ -108,6 +108,11 @@
Modify ThreadLocal memory leak detection to not report false positives
and to simplify implementation. (markt/kkolinko)
</update>
+ <add>
+ Basic memory leak detection was added to the standard Host
+ implementation and exposed via JMX to detect memory leaks on web
+ application reload. (markt/kkolinko)
+ </add>
</changelog>
</subsection>
<subsection name="Jasper">
@@ -150,6 +155,14 @@
</fix>
</changelog>
</subsection>
+ <subsection name="Webapps">
+ <changelog>
+ <add>
+ Make the new web application reload memory leak detection available
+ through the Manager application. (markt/kkolinko)
+ </add>
+ </changelog>
+ </subsection>
<subsection name="Other">
<changelog>
<fix>
Modified: tomcat/tc6.0.x/trunk/webapps/docs/html-manager-howto.xml
URL: http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/webapps/docs/html-manager-howto.xml?rev=915603&r1=915602&r2=915603&view=diff
==============================================================================
--- tomcat/tc6.0.x/trunk/webapps/docs/html-manager-howto.xml (original)
+++ tomcat/tc6.0.x/trunk/webapps/docs/html-manager-howto.xml Wed Feb 24 00:07:06 2010
@@ -36,7 +36,7 @@
Tomcat. This document is for the HTML web interface to the web application
<a href="manager-howto.html">manager</a>.</p>
-<p>The interface is divided into five sections:
+<p>The interface is divided into six sections:
<ul>
<li><strong>Message</strong> - Displays success and failure messages.</li>
<li><strong>Manager</strong> - General manager operations like list and
@@ -44,6 +44,7 @@
<li><strong>Applications</strong> - List of web applications and
commands.</li>
<li><strong>Deploy</strong> - Deploying web applications.</li>
+ <li><strong>Diagnostics</strong> - Identifying potential problems.</li>
<li><strong>Server Information</strong> - Information about the Tomcat
server.</li>
</ul>
@@ -546,6 +547,19 @@
</subsection>
</section>
+<section name="Diagnostics">
+
+<p><strong>The find leaks diagnostic triggers a full garbage collection. It
+should be used with extreme caution on production systems.</strong></p>
+
+<p>The find leaks diagnostic attempts to identify web applications that have
+caused memory leaks when they were reloaded. Results should always be confirmed
+with a profiler. The diagnostic uses additional functionality provided by the
+StandardHost implementation. It will not work if a custom host is used that
+does not extend StandardHost.</p>
+
+</section>
+
<section name="Server Information">
<p>This section displays information about Tomcat, the operating system of
Modified: tomcat/tc6.0.x/trunk/webapps/docs/manager-howto.xml
URL: http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/webapps/docs/manager-howto.xml?rev=915603&r1=915602&r2=915603&view=diff
==============================================================================
--- tomcat/tc6.0.x/trunk/webapps/docs/manager-howto.xml (original)
+++ tomcat/tc6.0.x/trunk/webapps/docs/manager-howto.xml Wed Feb 24 00:07:06 2010
@@ -51,6 +51,8 @@
<a href="#Stop an Existing Application">Stop an Existing Application</a><br />
<a href="#Undeploy an Existing Application">
Undeploy an Existing Application</a><br />
+<a href="#Server Status">Server Status</a><br />
+<a href="#Finding memory leaks">Finding memory leaks</a><br />
</blockquote>
<a href="#Executing Manager Commands With Ant">
Executing Manager Commands With Ant</a><br />
@@ -897,6 +899,35 @@
</subsection>
+<subsection name="Finding memory leaks">
+
+<source>
+http://localhost:8080/manager/findleaks
+</source>
+
+<p><strong>The find leaks diagnostic triggers a full garbage collection. It
+should be used with extreme caution on production systems.</strong></p>
+
+<p>The find leaks diagnostic attempts to identify web applications that have
+caused memory leaks when they were reloaded. Results should always be confirmed
+with a profiler. The diagnostic uses additional functionality provided by the
+StandardHost implementation. It will not work if a custom host is used that
+does not extend StandardHost.</p>
+
+<p>If this command succeeds, you will see a response like this:</p>
+<source>
+/leaking-webapp
+</source>
+
+<p>Each context path for a web application that is believed to have triggered a
+memory leak when it was reloaded will be listed on a new line. If an application
+has been reloaded several times, it may be listed several times.</p>
+
+<p>If the command does not succeed, the response will start with
+<code>FAIL</code> and include an error message.</p>
+
+</subsection>
+
<subsection name="Server Status">
<p>From this link , you can view information about the server.</p>
Modified: tomcat/tc6.0.x/trunk/webapps/manager/WEB-INF/web.xml
URL: http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/webapps/manager/WEB-INF/web.xml?rev=915603&r1=915602&r2=915603&view=diff
==============================================================================
--- tomcat/tc6.0.x/trunk/webapps/manager/WEB-INF/web.xml (original)
+++ tomcat/tc6.0.x/trunk/webapps/manager/WEB-INF/web.xml Wed Feb 24 00:07:06 2010
@@ -121,6 +121,10 @@
<url-pattern>/resources</url-pattern>
</servlet-mapping>
<servlet-mapping>
+ <servlet-name>Manager</servlet-name>
+ <url-pattern>/findleaks</url-pattern>
+ </servlet-mapping>
+ <servlet-mapping>
<servlet-name>Status</servlet-name>
<url-pattern>/status/*</url-pattern>
</servlet-mapping>
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Re: svn commit: r915603 - in /tomcat/tc6.0.x/trunk: ./ java/org/apache/catalina/core/
java/org/apache/catalina/loader/ java/org/apache/catalina/manager/ webapps/docs/
webapps/manager/WEB-INF/
Posted by Rainer Jung <ra...@kippdata.de>.
On 24.02.2010 11:47, Mark Thomas wrote:
> On 24/02/2010 10:18, Rainer Jung wrote:
>> On 24.02.2010 01:07, markt@apache.org wrote:
>>> Author: markt
>>> Date: Wed Feb 24 00:07:06 2010
>>> New Revision: 915603
>>>
>>> URL: http://svn.apache.org/viewvc?rev=915603&view=rev
>>> Log:
>>> Add basic memory leak detection for JMX and manager (kkolinko/markt)
>
>> Should we add a note, that the feature will not work in case System.gc()
>> has been disabled, e.g. by setting -XX:+DisableExplicitGC on the command
>> line (Sun VM)?
>
> More documentation is always good. There is, of course, no guarantee
> that the GC will run anyway.
OK, I'll have a look if noone beats me to it.
>> I think there's no good way yet to determine whether explicit GCs are
>> possible or not. One could check the input arguments provided by the
>> runtime platform mbean, but I think it's not worth it.
>
> I don't have the details (vendor, versions etc) to hand but you can get
> counts of GC via JMX. It may be viable - depending on which vendors/jvms
> support it - to check the GC count before and after we try to trigger it.
Good point. It's
java.lang.management.GarbageCollectorMXBean.getCollectionCount()
which is in java.lang.management and not only in sun.com.management.
Problem is, that even for Sun VM it's not trivial to find the right one.
In general, there are at least two of those, one for the young
generation (minor GC), and the other one for tenured, perm and young
(major GC). One could use the name of the bean, or the names of the
memory pools it handles. But as we know there are various possible
implementations using bean names containing "MarkSweepCompact", "PS
MarkSweep", "ConcurrentMarkSweep" and memory pool names containing
"Tenured Gen", "PS Old Gen", "CMS Old Gen". Then the there's G1 and I
didn't have a look how the names are in that case. So all in all I see
no robust way to find the right GarbageCollectorMXBean.
Regards,
Rainer
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Re: svn commit: r915603 - in /tomcat/tc6.0.x/trunk: ./ java/org/apache/catalina/core/
java/org/apache/catalina/loader/ java/org/apache/catalina/manager/ webapps/docs/
webapps/manager/WEB-INF/
Posted by Mark Thomas <ma...@apache.org>.
On 24/02/2010 10:18, Rainer Jung wrote:
> On 24.02.2010 01:07, markt@apache.org wrote:
>> Author: markt
>> Date: Wed Feb 24 00:07:06 2010
>> New Revision: 915603
>>
>> URL: http://svn.apache.org/viewvc?rev=915603&view=rev
>> Log:
>> Add basic memory leak detection for JMX and manager (kkolinko/markt)
> Should we add a note, that the feature will not work in case System.gc()
> has been disabled, e.g. by setting -XX:+DisableExplicitGC on the command
> line (Sun VM)?
More documentation is always good. There is, of course, no guarantee
that the GC will run anyway.
> I think there's no good way yet to determine whether explicit GCs are
> possible or not. One could check the input arguments provided by the
> runtime platform mbean, but I think it's not worth it.
I don't have the details (vendor, versions etc) to hand but you can get
counts of GC via JMX. It may be viable - depending on which vendors/jvms
support it - to check the GC count before and after we try to trigger it.
Mark
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Re: svn commit: r915603 - in /tomcat/tc6.0.x/trunk: ./ java/org/apache/catalina/core/
java/org/apache/catalina/loader/ java/org/apache/catalina/manager/ webapps/docs/
webapps/manager/WEB-INF/
Posted by Rainer Jung <ra...@kippdata.de>.
On 24.02.2010 01:07, markt@apache.org wrote:
> Author: markt
> Date: Wed Feb 24 00:07:06 2010
> New Revision: 915603
>
> URL: http://svn.apache.org/viewvc?rev=915603&view=rev
> Log:
> Add basic memory leak detection for JMX and manager (kkolinko/markt)
> Modified: tomcat/tc6.0.x/trunk/java/org/apache/catalina/core/StandardHost.java
> URL: http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/java/org/apache/catalina/core/StandardHost.java?rev=915603&r1=915602&r2=915603&view=diff
> ==============================================================================
> --- tomcat/tc6.0.x/trunk/java/org/apache/catalina/core/StandardHost.java (original)
> +++ tomcat/tc6.0.x/trunk/java/org/apache/catalina/core/StandardHost.java Wed Feb 24 00:07:06 2010
> @@ -529,6 +549,49 @@
> + * Attempt to identify the contexts that have a class loader memory leak.
> + * This is usually triggered on context reload. Note: This method attempts
> + * to force a full garbage collection. This should be used with extreme
> + * caution on a production system.
> + */
> + public String[] findReloadedContextMemoryLeaks() {
> +
> + System.gc();
> Modified: tomcat/tc6.0.x/trunk/webapps/docs/html-manager-howto.xml
> URL: http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/webapps/docs/html-manager-howto.xml?rev=915603&r1=915602&r2=915603&view=diff
> ==============================================================================
> +<section name="Diagnostics">
> +
> +<p><strong>The find leaks diagnostic triggers a full garbage collection. It
> +should be used with extreme caution on production systems.</strong></p>
> +
> +<p>The find leaks diagnostic attempts to identify web applications that have
> +caused memory leaks when they were reloaded. Results should always be confirmed
> +with a profiler. The diagnostic uses additional functionality provided by the
> +StandardHost implementation. It will not work if a custom host is used that
> +does not extend StandardHost.</p>
> +
> Modified: tomcat/tc6.0.x/trunk/webapps/docs/manager-howto.xml
> URL: http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/webapps/docs/manager-howto.xml?rev=915603&r1=915602&r2=915603&view=diff
> ==============================================================================
> --- tomcat/tc6.0.x/trunk/webapps/docs/manager-howto.xml (original)
> +++ tomcat/tc6.0.x/trunk/webapps/docs/manager-howto.xml Wed Feb 24 00:07:06 2010
> +<p><strong>The find leaks diagnostic triggers a full garbage collection. It
> +should be used with extreme caution on production systems.</strong></p>
Should we add a note, that the feature will not work in case System.gc()
has been disabled, e.g. by setting -XX:+DisableExplicitGC on the
command line (Sun VM)?
I think there's no good way yet to determine whether explicit GCs are
possible or not. One could check the input arguments provided by the
runtime platform mbean, but I think it's not worth it.
Cool stuff otherwise!
Regards,
Rainer
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