Bob created IGNITE-17462:
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Summary: Use of reflection to load NullAppender causes
NullPointerException when NullAppender is removed
Key: IGNITE-17462
URL: https://issues.apache.org/jira/browse/IGNITE-17462
Project: Ignite
Issue Type: Bug
Components: general
Affects Versions: 2.13
Reporter: Bob
When using log4j 2.17, the use of Java reflection to create the NullAppender
instance during node start causes the NullAppender to be created with
NullAppender.name=null. Later during node start, when the NullAppender is being
removed, a NullPointerException occurs because of the null name. While log4j
2.18 changed the code slightly to prevent the NPE from occurring, the side
effect is that the NullAppender never actually gets removed.
Line 8983 of
/core/src/main/java/org/apache/ignite/internal/util/IgniteUtils.java does the
following:
nullApp =
Class.forName("org.apache.log4j.varia.NullAppender").newInstance();
This creates the NullAppender with name=null. The documentaion for NullAppender
states it should be created with NullAppender.createAppender(), which will make
sure name is not null, which will in turn make it possible to remove the
NullAppender later on. It also states it should NOT be created with new
NullAppender(), which is what happens when newInstance() is called.
This issue is causing some pain to avoid the NPEs when running alongside Spark
3.3, which pulls in Log4j 2.17.2. Basically, the only way to get this
environment to work is to make sure none of the Log4j v1 classes are present in
the classpath, including those provided by the log4j-1.2-api jar that gets
bundled with log4j-api and log4j-core.
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