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Posted to dev@tomcat.apache.org by ma...@apache.org on 2013/06/24 16:06:24 UTC

svn commit: r1496061 - in /tomcat/trunk: java/org/apache/catalina/core/JreMemoryLeakPreventionListener.java webapps/docs/config/listeners.xml

Author: markt
Date: Mon Jun 24 14:06:24 2013
New Revision: 1496061

URL: http://svn.apache.org/r1496061
Log:
Changes to java.beans.Introspector#flushCaches() mean that AppContext protection is not required from 1.7.0_02 onwards.
Changes to AppContext meant the memory leak protection required a graphical environment from 1.7.0_25 onwards.

Modified:
    tomcat/trunk/java/org/apache/catalina/core/JreMemoryLeakPreventionListener.java
    tomcat/trunk/webapps/docs/config/listeners.xml

Modified: tomcat/trunk/java/org/apache/catalina/core/JreMemoryLeakPreventionListener.java
URL: http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/catalina/core/JreMemoryLeakPreventionListener.java?rev=1496061&r1=1496060&r2=1496061&view=diff
==============================================================================
--- tomcat/trunk/java/org/apache/catalina/core/JreMemoryLeakPreventionListener.java (original)
+++ tomcat/trunk/java/org/apache/catalina/core/JreMemoryLeakPreventionListener.java Mon Jun 24 14:06:24 2013
@@ -59,12 +59,30 @@ public class JreMemoryLeakPreventionList
     private static final StringManager sm =
         StringManager.getManager(Constants.Package);
 
+    private static final boolean IS_JAVA_7_OR_LATER;
+
+    static {
+        boolean isJava7OrLater;
+        try {
+            Class.forName("java.util.Objects");
+            isJava7OrLater = true;
+        } catch (ClassNotFoundException e) {
+            isJava7OrLater = false;
+        }
+        IS_JAVA_7_OR_LATER = isJava7OrLater;
+    }
+
     /**
      * Protect against the memory leak caused when the first call to
      * <code>sun.awt.AppContext.getAppContext()</code> is triggered by a web
-     * application. Defaults to <code>true</code>.
+     * application. Defaults to <code>true</code> for Java 6 and earlier (since
+     * it is used by {@link java.beans.Introspector#flushCaches()}) but defaults
+     * to <code>false</code> for Java 7 and later since
+     * {@link java.beans.Introspector#flushCaches()} no longer uses AppContext
+     * from 1.7.0_02 onwards. Also, from 1.7.0_25 onwards, calling this method
+     * requires a graphical environment and starts an AWT thread.
      */
-    private boolean appContextProtection = true;
+    private boolean appContextProtection = !IS_JAVA_7_OR_LATER;
     public boolean isAppContextProtection() { return appContextProtection; }
     public void setAppContextProtection(boolean appContextProtection) {
         this.appContextProtection = appContextProtection;
@@ -250,8 +268,15 @@ public class JreMemoryLeakPreventionList
                  * due to eventual calls to getAppContext() are:
                  * - Google Web Toolkit via its use of javax.imageio
                  * - Tomcat via its use of java.beans.Introspector.flushCaches()
-                 *   in 1.6.0_15 onwards
+                 *   in 1.6.0_15 to 1.7.0_01. From 1.7.0_02 onwards use of
+                 *   AppContext by Introspector.flushCaches() was replaced with
+                 *   ThreadGroupContext
                  * - others TBD
+                 *
+                 * From 1.7.0_25 onwards, a call to
+                 * sun.awt.AppContext.getAppContext() results in a thread being
+                 * started named AWT-AppKit that requires a graphic environment
+                 * to be available.
                  */
 
                 // Trigger a call to sun.awt.AppContext.getAppContext(). This

Modified: tomcat/trunk/webapps/docs/config/listeners.xml
URL: http://svn.apache.org/viewvc/tomcat/trunk/webapps/docs/config/listeners.xml?rev=1496061&r1=1496060&r2=1496061&view=diff
==============================================================================
--- tomcat/trunk/webapps/docs/config/listeners.xml (original)
+++ tomcat/trunk/webapps/docs/config/listeners.xml Mon Jun 24 14:06:24 2013
@@ -178,9 +178,11 @@
         <p>Enables protection so that calls to
         <code>sun.awt.AppContext.getAppContext()</code> triggered by a web
         application do not result in a memory leak. Note that a call to this
-        method will be triggered as part of the web application stop process so
-        it is strongly recommended that this protection is enabled. The default
-        is <code>true</code>.</p>
+        method will be triggered as part of the web application stop process
+        when running on Java 6 and earlier. It is therefore strongly recommended
+        that this protection is enabled when running on Java 6 and earlier. The
+        default is <code>true</code> for Java 6 and earlier versions. The
+        default is <code>false</code> for Java 7 and later versions.</p>
       </attribute>
 
       <attribute name="AWTThreadProtection" required="false">



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Re: svn commit: r1496061 - in /tomcat/trunk: java/org/apache/catalina/core/JreMemoryLeakPreventionListener.java webapps/docs/config/listeners.xml

Posted by Christopher Schultz <ch...@christopherschultz.net>.
Mark,

On 6/24/13 10:06 AM, markt@apache.org wrote:
> Author: markt
> Date: Mon Jun 24 14:06:24 2013
> New Revision: 1496061
> 
> URL: http://svn.apache.org/r1496061
> Log:
> Changes to java.beans.Introspector#flushCaches() mean that AppContext protection is not required from 1.7.0_02 onwards.
> Changes to AppContext meant the memory leak protection required a graphical environment from 1.7.0_25 onwards.
> 
> Modified:
>     tomcat/trunk/java/org/apache/catalina/core/JreMemoryLeakPreventionListener.java
>     tomcat/trunk/webapps/docs/config/listeners.xml
> 
> Modified: tomcat/trunk/java/org/apache/catalina/core/JreMemoryLeakPreventionListener.java
> URL: http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/catalina/core/JreMemoryLeakPreventionListener.java?rev=1496061&r1=1496060&r2=1496061&view=diff
> ==============================================================================
> --- tomcat/trunk/java/org/apache/catalina/core/JreMemoryLeakPreventionListener.java (original)
> +++ tomcat/trunk/java/org/apache/catalina/core/JreMemoryLeakPreventionListener.java Mon Jun 24 14:06:24 2013
> @@ -59,12 +59,30 @@ public class JreMemoryLeakPreventionList
>      private static final StringManager sm =
>          StringManager.getManager(Constants.Package);
>  
> +    private static final boolean IS_JAVA_7_OR_LATER;
> +
> +    static {
> +        boolean isJava7OrLater;
> +        try {
> +            Class.forName("java.util.Objects");
> +            isJava7OrLater = true;
> +        } catch (ClassNotFoundException e) {
> +            isJava7OrLater = false;
> +        }
> +        IS_JAVA_7_OR_LATER = isJava7OrLater;
> +    }

Isn't there a better way to detect Java versions? Maybe detect the
version string and do a comparison?

-chris