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From Matt Sicker <boa...@gmail.com>
Subject Re: Fwd: logging-log4j2 git commit: [LOG4J2-1642]
Date Wed, 07 Dec 2016 04:52:58 GMT
In an OSGi environment, the best ClassLoader to use for something in
log4j-core is one obtained from a class in log4j-core. Come to think of it,
it'd be better to do something like this:

LoggerContext.class.getClassLoader().loadClass(...);

On 6 December 2016 at 22:39, Gary Gregory <garydgregory@gmail.com> wrote:

> I think one of the points here is that a class is loaded from a specific
> class loader. This is not clear from the code or comments. I am not sure
> this 100% correct either but if that fixes at least the null class loader
> NPE then that is a good thing. Especially if the fix is less hacky than
> inially proposed. I am open to better comments and code ;-)
>
> Gary
>
>
> On Dec 6, 2016 8:24 PM, "Matt Sicker" <boards@gmail.com> wrote:
>
> I'm not sure if that LoaderUtil line will work properly everywhere. You
> already implicitly load the class by referencing the class's .class
> property I think. Either way, a more amusing and surefire way to make it
> load would be:
>
> ExecutorServices.class.getClassLoader().loadClass(ExecutorSe
> rvices.class.getName());
>
> Or use one of the LoaderUtil/Loader methods that takes a ClassLoader
> argument to avoid an NPE if log4j is loaded as a bootstrap class somehow.
>
> ---------- Forwarded message ----------
> From: <ggregory@apache.org>
> Date: 6 December 2016 at 18:07
> Subject: logging-log4j2 git commit: [LOG4J2-1642]
> To: commits@logging.apache.org
>
>
> Repository: logging-log4j2
> Updated Branches:
>   refs/heads/master 2eb02c827 -> bdac7f223
>
>
> [LOG4J2-1642]
>
> DefaultShutdownCallbackRegistry can throw a NoClassDefFoundError.
>
> Project: http://git-wip-us.apache.org/repos/asf/logging-log4j2/repo
> Commit: http://git-wip-us.apache.org/repos/asf/logging-log4j2/commit
> /bdac7f22
> Tree: http://git-wip-us.apache.org/repos/asf/logging-log4j2/tree/bdac7f22
> Diff: http://git-wip-us.apache.org/repos/asf/logging-log4j2/diff/bdac7f22
>
> Branch: refs/heads/master
> Commit: bdac7f223b41dfbbf204ca924d08e6ed86c76769
> Parents: 2eb02c8
> Author: Johno Crawford <johno@sulake.com>
> Authored: Tue Dec 6 16:07:52 2016 -0800
> Committer: Gary Gregory <garydgregory@gmail.com>
> Committed: Tue Dec 6 16:07:52 2016 -0800
>
> ----------------------------------------------------------------------
>  .../apache/logging/log4j/core/LoggerContext.java    | 16 +++++++++++++---
>  .../core/util/DefaultShutdownCallbackRegistry.java  |  9 +++++++--
>  src/changes/changes.xml                             |  3 +++
>  3 files changed, 23 insertions(+), 5 deletions(-)
> ----------------------------------------------------------------------
>
>
> http://git-wip-us.apache.org/repos/asf/logging-log4j2/blob/b
> dac7f22/log4j-core/src/main/java/org/apache/logging/log4j/co
> re/LoggerContext.java
> ----------------------------------------------------------------------
> diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/LoggerContext.java
> b/log4j-core/src/main/java/org/apache/logging/log4j/core/Log
> gerContext.java
> index 6902ade..4c4845e 100644
> --- a/log4j-core/src/main/java/org/apache/logging/log4j/core/Log
> gerContext.java
> +++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/Log
> gerContext.java
> @@ -16,6 +16,8 @@
>   */
>  package org.apache.logging.log4j.core;
>
> +import static org.apache.logging.log4j.core.
> util.ShutdownCallbackRegistry.SHUTDOWN_HOOK_MARKER;
> +
>  import java.beans.PropertyChangeEvent;
>  import java.beans.PropertyChangeListener;
>  import java.io.File;
> @@ -52,10 +54,9 @@ import org.apache.logging.log4j.spi.AbstractLogger;
>  import org.apache.logging.log4j.spi.LoggerContextFactory;
>  import org.apache.logging.log4j.spi.LoggerRegistry;
>  import org.apache.logging.log4j.spi.Terminable;
> +import org.apache.logging.log4j.util.LoaderUtil;
>  import org.apache.logging.log4j.util.PropertiesUtil;
>
> -import static org.apache.logging.log4j.core.
> util.ShutdownCallbackRegistry.SHUTDOWN_HOOK_MARKER;
> -
>  /**
>   * The LoggerContext is the anchor for the logging system. It maintains a
> list of all the loggers requested by
>   * applications and a reference to the Configuration. The Configuration
> will contain the configured loggers, appenders,
> @@ -63,7 +64,16 @@ import static org.apache.logging.log4j.core.
> util.ShutdownCallbackRegistry.SHUTDO
>   */
>  public class LoggerContext extends AbstractLifeCycle
>          implements org.apache.logging.log4j.spi.LoggerContext,
> AutoCloseable, Terminable, ConfigurationListener {
> -
> +
> +    static {
> +        try {
> +            // LOG4J2-1642 preload ExecutorServices as it is used in
> shutdown hook
> +            LoaderUtil.loadClass(ExecutorServices.class.getName());
> +        } catch (final Exception e) {
> +            LOGGER.error("Failed to preload ExecutorServices class.", e);
> +        }
> +    }
> +
>      /**
>       * Property name of the property change event fired if the
> configuration is changed.
>       */
>
> http://git-wip-us.apache.org/repos/asf/logging-log4j2/blob/b
> dac7f22/log4j-core/src/main/java/org/apache/logging/log4j/co
> re/util/DefaultShutdownCallbackRegistry.java
> ----------------------------------------------------------------------
> diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/uti
> l/DefaultShutdownCallbackRegistry.java b/log4j-core/src/main/java/org
> /apache/logging/log4j/core/util/DefaultShutdownCallbackRegistry.java
> index 48d54b6..d2be690 100644
> --- a/log4j-core/src/main/java/org/apache/logging/log4j/core/uti
> l/DefaultShutdownCallbackRegistry.java
> +++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/uti
> l/DefaultShutdownCallbackRegistry.java
> @@ -72,8 +72,13 @@ public class DefaultShutdownCallbackRegistry
> implements ShutdownCallbackRegistry
>              for (final Runnable hook : hooks) {
>                  try {
>                      hook.run();
> -                } catch (final Throwable t) {
> -                    LOGGER.error(SHUTDOWN_HOOK_MARKER, "Caught exception
> executing shutdown hook {}", hook, t);
> +                } catch (final Throwable t1) {
> +                    try {
> +                        LOGGER.error(SHUTDOWN_HOOK_MARKER, "Caught
> exception executing shutdown hook {}", hook, t1);
> +                    } catch (final Throwable t2) {
> +                        System.err.println("Caught exception logging
> exception");
> +                        t1.printStackTrace();
> +                    }
>                  }
>              }
>              state.set(State.STOPPED);
>
> http://git-wip-us.apache.org/repos/asf/logging-log4j2/blob/b
> dac7f22/src/changes/changes.xml
> ----------------------------------------------------------------------
> diff --git a/src/changes/changes.xml b/src/changes/changes.xml
> index a6279b2..4fa7e54 100644
> --- a/src/changes/changes.xml
> +++ b/src/changes/changes.xml
> @@ -147,6 +147,9 @@
>        <action issue="LOG4J2-1687" dev="ggregory" type="fix"
> due-to="Robert Christiansen">
>          NPE in ThrowableProxy when resolving stack in Java EE/OSGi
> environment.
>        </action>
> +      <action issue="LOG4J2-1642" dev="ggregory" type="fix" due-to="Johno
> Crawford">
> +        DefaultShutdownCallbackRegistry can throw a NoClassDefFoundError.
> +      </action>
>        <action issue="LOG4J2-1644" dev="ggregory" type="update"
> due-to="Tim Gokcen, Pavel Sivolobtchik">
>          Inefficient locking in AbstractLoggerAdapter.
>        </action>
>
>
>
>
> --
> Matt Sicker <boards@gmail.com>
>
>
>


-- 
Matt Sicker <boards@gmail.com>

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