Move from a global system property to a per Context attribute for clearing static...

Change the default as this should no longer be an issue with modern JVMs and the other memory leak protection provided in Tomcat 7.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@885889 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/java/org/apache/catalina/core/StandardContext.java b/java/org/apache/catalina/core/StandardContext.java
index ef6d31e..9b77f7d 100644 (file)
--- a/java/org/apache/catalina/core/StandardContext.java
+++ b/java/org/apache/catalina/core/StandardContext.java
@@ -711,13 +711,13 @@ public class StandardContext
     /**
      * Attribute value used to turn on/off XML validation
      */
-     private boolean tldValidation = false;
+    private boolean tldValidation = false;
 
 
     /**
      * Attribute value used to turn on/off TLD XML namespace validation
      */
-     private boolean tldNamespaceAware = false;
+    private boolean tldNamespaceAware = false;
 
 
     /**
@@ -736,8 +736,17 @@ public class StandardContext
      */
     private JarScanner jarScanner = null;
 
-
-
+    /**
+     * Should Tomcat attempt to null out any static or final fields from loaded
+     * classes when a web application is stopped as a work around for apparent
+     * garbage collection bugs and application coding errors. There have been
+     * some issues reported with log4j when this option is true. Applications
+     * without memory leaks using recent JVMs should operate correctly with this
+     * option set to <code>false</code>. If not specified, the default value of
+     * <code>false</code> will be used. 
+     */
+    private boolean clearReferencesStatic = false;
+    
     // ----------------------------------------------------- Context Properties
 
 
@@ -2069,6 +2078,32 @@ public class StandardContext
     }
 
 
+    /**
+     * Return the clearReferencesStatic flag for this Context.
+     */
+    public boolean getClearReferencesStatic() {
+
+        return (this.clearReferencesStatic);
+
+    }
+
+
+    /**
+     * Set the clearReferencesStatic feature for this Context.
+     *
+     * @param clearReferencesStatic The new flag value
+     */
+    public void setClearReferencesStatic(boolean clearReferencesStatic) {
+
+        boolean oldClearReferencesStatic = this.clearReferencesStatic;
+        this.clearReferencesStatic = clearReferencesStatic;
+        support.firePropertyChange("clearReferencesStatic",
+                                   oldClearReferencesStatic,
+                                   this.clearReferencesStatic);
+
+    }
+
+
     // -------------------------------------------------------- Context Methods
 
 

diff --git a/java/org/apache/catalina/loader/WebappClassLoader.java b/java/org/apache/catalina/loader/WebappClassLoader.java
index ef89142..2b0f546 100644 (file)
--- a/java/org/apache/catalina/loader/WebappClassLoader.java
+++ b/java/org/apache/catalina/loader/WebappClassLoader.java
@@ -119,9 +119,6 @@ public class WebappClassLoader
     private static final List<String> JVM_THREAD_GROUP_NAMES =
         new ArrayList<String>();
 
-    public static final boolean ENABLE_CLEAR_REFERENCES = 
-        Boolean.valueOf(System.getProperty("org.apache.catalina.loader.WebappClassLoader.ENABLE_CLEAR_REFERENCES", "true")).booleanValue();
-    
     static {
         JVM_THREAD_GROUP_NAMES.add("system");
         JVM_THREAD_GROUP_NAMES.add("RMI Runtime");
@@ -411,6 +408,17 @@ public class WebappClassLoader
     protected Permission allPermission = new java.security.AllPermission();
 
 
+    /**
+     * Should Tomcat attempt to null out any static or final fields from loaded
+     * classes when a web application is stopped as a work around for apparent
+     * garbage collection bugs and application coding errors. There have been
+     * some issues reported with log4j when this option is true. Applications
+     * without memory leaks using recent JVMs should operate correctly with this
+     * option set to <code>false</code>. If not specified, the default value of
+     * <code>false</code> will be used. 
+     */
+    private boolean clearReferencesStatic = false;
+
     // ------------------------------------------------------------- Properties
 
 
@@ -564,6 +572,25 @@ public class WebappClassLoader
          parent = pcl;
      }
 
+     /**
+      * Return the clearReferencesStatic flag for this Context.
+      */
+     public boolean getClearReferencesStatic() {
+         return (this.clearReferencesStatic);
+     }
+
+
+     /**
+      * Set the clearReferencesStatic feature for this Context.
+      *
+      * @param clearReferencesStatic The new flag value
+      */
+     public void setClearReferencesStatic(boolean clearReferencesStatic) {
+         this.clearReferencesStatic = clearReferencesStatic;
+     }
+
+
+
     // ------------------------------------------------------- Reloader Methods
 
 
@@ -1653,7 +1680,7 @@ public class WebappClassLoader
         
         // Null out any static or final fields from loaded classes,
         // as a workaround for apparent garbage collection bugs
-        if (ENABLE_CLEAR_REFERENCES) {
+        if (clearReferencesStatic) {
             clearReferencesStaticFinal();
         }
         

diff --git a/java/org/apache/catalina/loader/WebappLoader.java b/java/org/apache/catalina/loader/WebappLoader.java
index 6d1d595..58367e9 100644 (file)
--- a/java/org/apache/catalina/loader/WebappLoader.java
+++ b/java/org/apache/catalina/loader/WebappLoader.java
@@ -637,8 +637,13 @@ public class WebappLoader
             classLoader = createClassLoader();
             classLoader.setResources(container.getResources());
             classLoader.setDelegate(this.delegate);
-            if (container instanceof StandardContext)
-                classLoader.setAntiJARLocking(((StandardContext) container).getAntiJARLocking());
+            if (container instanceof StandardContext) {
+                classLoader.setAntiJARLocking(
+                        ((StandardContext) container).getAntiJARLocking());
+                classLoader.setClearReferencesStatic(
+                        ((StandardContext) container).getClearReferencesStatic());
+                
+            }
 
             for (int i = 0; i < repositories.length; i++) {
                 classLoader.addRepository(repositories[i]);

diff --git a/webapps/docs/config/context.xml b/webapps/docs/config/context.xml
index 96239e7..e79d8ad 100644 (file)
--- a/webapps/docs/config/context.xml
+++ b/webapps/docs/config/context.xml
@@ -328,6 +328,17 @@
         of the flag is <code>true</code>.</p>
       </attribute>
 
+      <attribute name="clearReferencesStatic" required = "false">
+        <p>If <code>true</code>, Tomcat attempts to null out any static or final
+        fields from loaded classes when a web application is stopped as a work
+        around for apparent garbage collection bugs and application coding
+        errors. There have been some issues reported with log4j when this
+        is <code>true</code>. Applications without memory leaks using recent
+        JVMs should operate correctly with this attribute set to
+        <code>false</code>. If not specified, the default value of
+        <code>false</code> will be used.</p>
+      </attribute>
+
       <attribute name="processTlds" required="false">
         <p>Whether the context should process TLDs on startup.  The default
         is true.  The false setting is intended for special cases

diff --git a/webapps/docs/config/systemprops.xml b/webapps/docs/config/systemprops.xml
index 06f0563..7a43ba0 100644 (file)
--- a/webapps/docs/config/systemprops.xml
+++ b/webapps/docs/config/systemprops.xml
@@ -403,20 +403,6 @@
       configured on the <a href="engine.html">Engine</a> element.</p>
     </property>
 
-    <property
-    name="org.apache.catalina.loader. WebappClassLoader.ENABLE_CLEAR_REFERENCES">
-      <p>If <code>true</code>, Tomcat attempts to null out any static or final
-      fields from loaded classes when a web application is stopped as a work
-      around for apparent garbage collection bugs and application coding errors.
-      </p>
-      <p>There have been some issues reported with log4j when this option is
-      <code>true</code>.</p>
-      <p>Applications without memory leaks using recent JVMs should operate
-      correctly with this option set to <code>false</code>.</p>
-      <p>If not specified, the default value of <code>true</code> will be used.
-      </p>
-    </property>
-
     <property name="catalina.config">
       <p>The URL for the catalina.properties configuration file.</p>
     </property>