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Posted to notifications@logging.apache.org by "bfreitastgtg (via GitHub)" <gi...@apache.org> on 2024/11/26 13:45:42 UTC
[I] Exception thrown in class annotated with @Plugin that uses a logger (logging-log4j2)
bfreitastgtg opened a new issue, #3240:
URL: https://github.com/apache/logging-log4j2/issues/3240
## Description
Trying to use a logger in a class annotated with `@Plugin` from `org.apache.logging.log4j.core.config.plugins` throws an exception. The same problem does not happen on versions 2.23.1, 2.24.0 and 2.24.1.
## Configuration
**Version:** 2.24.2
**Operating system:** linux
**JDK:** Amazon Correto, 21
## Logs
```
2024-11-26T08:33:59.000998374Z main ERROR Unable to create Lookup for myplugin java.lang.IllegalArgumentException: java.lang.ExceptionInInitializerError
at org.apache.logging.log4j.core.util.ReflectionUtil.instantiate(ReflectionUtil.java:192)
at org.apache.logging.log4j.core.lookup.Interpolator.<init>(Interpolator.java:90)
at org.apache.logging.log4j.core.lookup.Interpolator.<init>(Interpolator.java:109)
at org.apache.logging.log4j.core.config.AbstractConfiguration.<init>(AbstractConfiguration.java:137)
at org.apache.logging.log4j.core.config.NullConfiguration.<init>(NullConfiguration.java:32)
at org.apache.logging.log4j.core.LoggerContext.<clinit>(LoggerContext.java:77)
at org.apache.logging.log4j.core.selector.ClassLoaderContextSelector.createContext(ClassLoaderContextSelector.java:265)
at org.apache.logging.log4j.core.selector.ClassLoaderContextSelector.locateContext(ClassLoaderContextSelector.java:224)
at org.apache.logging.log4j.core.selector.ClassLoaderContextSelector.getContext(ClassLoaderContextSelector.java:142)
at org.apache.logging.log4j.core.selector.ClassLoaderContextSelector.getContext(ClassLoaderContextSelector.java:125)
at org.apache.logging.log4j.core.selector.ClassLoaderContextSelector.getContext(ClassLoaderContextSelector.java:119)
at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:148)
at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:46)
at org.apache.logging.log4j.LogManager.getContext(LogManager.java:138)
at org.apache.logging.log4j.spi.AbstractLoggerAdapter.getContext(AbstractLoggerAdapter.java:136)
at org.apache.logging.slf4j.Log4jLoggerFactory.getContext(Log4jLoggerFactory.java:58)
at org.apache.logging.log4j.spi.AbstractLoggerAdapter.getLogger(AbstractLoggerAdapter.java:46)
at org.apache.logging.slf4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:32)
at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:432)
at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:457)
(...)
Caused by: java.lang.ExceptionInInitializerError
at java.base/jdk.internal.misc.Unsafe.ensureClassInitialized0(Native Method)
at java.base/jdk.internal.misc.Unsafe.ensureClassInitialized(Unsafe.java:1160)
at java.base/jdk.internal.reflect.MethodHandleAccessorFactory.ensureClassInitialized(MethodHandleAccessorFactory.java:300)
at java.base/jdk.internal.reflect.MethodHandleAccessorFactory.newConstructorAccessor(MethodHandleAccessorFactory.java:103)
at java.base/jdk.internal.reflect.ReflectionFactory.newConstructorAccessor(ReflectionFactory.java:200)
at java.base/java.lang.reflect.Constructor.acquireConstructorAccessor(Constructor.java:549)
at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)
at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:486)
at org.apache.logging.log4j.core.util.ReflectionUtil.instantiate(ReflectionUtil.java:188)
... 20 more
Caused by: java.lang.NullPointerException: messageFactory
at java.base/java.util.Objects.requireNonNull(Objects.java:259)
at org.apache.logging.log4j.core.util.internal.InternalLoggerRegistry.computeIfAbsent(InternalLoggerRegistry.java:135)
at org.apache.logging.log4j.core.LoggerContext.getLogger(LoggerContext.java:530)
at org.apache.logging.log4j.core.LoggerContext.getLogger(LoggerContext.java:503)
at org.apache.logging.log4j.core.LoggerContext.getLogger(LoggerContext.java:65)
at org.apache.logging.slf4j.Log4jLoggerFactory.newLogger(Log4jLoggerFactory.java:49)
at org.apache.logging.slf4j.Log4jLoggerFactory.newLogger(Log4jLoggerFactory.java:32)
at org.apache.logging.log4j.spi.AbstractLoggerAdapter.getLogger(AbstractLoggerAdapter.java:52)
at org.apache.logging.slf4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:32)
at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:432)
at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:457)
(...)
... 29 more
```
## Reproduction
The code below used to run fine, then after upgrading to 2.24.2 it started throwing on application startup. Getting rid of the `LOGGER` variable "fixes" the problem.
```
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.lookup.StrLookup;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
@Plugin(name = "MyPlugin", category = StrLookup.CATEGORY)
public class MyPlugin implements StrLookup {
private static final Logger LOGGER = LoggerFactory.getLogger(MyPlugin.class);
static {
LOGGER.info("Log stuff");
}
@Override
public String lookup(String key) {
return "";
}
@Override
public String lookup(LogEvent event, String key) {
return "";
}
}
```
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Re: [I] Exception thrown in class annotated with @Plugin that uses a logger (logging-log4j2)
Posted by "ppkarwasz (via GitHub)" <gi...@apache.org>.
ppkarwasz commented on issue #3240:
URL: https://github.com/apache/logging-log4j2/issues/3240#issuecomment-2501263468
@bfreitastgtg,
Thanks for reporting it. Log4j loads all annotated implementations of `StrLookup` in the static initialization of `LoggerContext`. When you class requests the logger, `LoggerContext` is not completely initialized. You will get all sorts of NPEs in this case.
There is a special logger (see [Status Logger](https://logging.apache.org/log4j/2.x/manual/status-logger.html)) that you can use in Log4j Plugins, but you **should** not use loggers obtained from `LogManager` or some foreign logging API bridged to Log4j API.
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Re: [I] Exception thrown in class annotated with @Plugin that uses a logger (logging-log4j2)
Posted by "bfreitastgtg (via GitHub)" <gi...@apache.org>.
bfreitastgtg commented on issue #3240:
URL: https://github.com/apache/logging-log4j2/issues/3240#issuecomment-2503466956
Hey @ppkarwasz , thanks for the quick reply. I tested and using a `StatusLogger` worked, but the question remains: why we suddenly needed to use it? As mentioned in the description, using a regular logger worked fine before `2.24.2`.
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Re: [I] Exception thrown in class annotated with @Plugin that uses a logger (logging-log4j2)
Posted by "ppkarwasz (via GitHub)" <gi...@apache.org>.
ppkarwasz commented on issue #3240:
URL: https://github.com/apache/logging-log4j2/issues/3240#issuecomment-2503683841
> Hey @ppkarwasz , thanks for the quick reply. I tested and using a `StatusLogger` worked, but the question remains: why we suddenly needed to use it? As mentioned in the description, using a regular logger worked fine before `2.24.2`.
The problem you are encountering is due to the `DEFAULT_MESSAGE_FACTORY` field being uninitialized (so `null`).
Up to Log4j 2.22.x, that field was in the Log4j API (its classes are initialized before `LoggerContext`) and was initialized using reflection and a configuration property specific to Log4j 2 ([the `log4j2.messageFactory` property](https://logging.apache.org/log4j/2.x/manual/systemproperties.html#log4j2.messageFactory)). That solution is no longer viable:
- It is not extensible. Since the release of `2.24.0`, Log4j Core 3 is based on the same version of Log4j API as Log4j Core 2 (see [documentation](https://logging.apache.org/log4j/3.x/manual/api.html)), but uses dependency injection for many services (including `MessageFactory`).
- It causes problems for GraalVM, since we would need to register with GraalVM all possible `MessageFactory` implementations in advance.
- It causes other initialization problems: since 2.23.x `StatusLogger` uses `AbstractLogger`, but is initialized **before** `PropertiesUtil`, which is used to determine the right `MessageFactory`.
These are the main reasons we moved the initialization of the default message factory at a later stage.
**Note**: we can easily fix the initialization problem, by moving `DEFAULT_MESSAGE_FACTORY` at the top of the `LoggerContext` class, but I have mixed feeling about this approach:
- I don't think it is needed. Using any `o.a.l.l.Logger` other than `o.a.l.l.status.StatusLogger` in a Log4j Core Plugin class is IMHO bad practice. Using an `org.slf4j.Logger` in such a class is even less recommended.
- The real problem is elsewhere: the `DefaultConfiguration` and `NullConfiguration` implementations used by `LoggerContext` before and after the real configuration is loaded, should probably be pretty minimal and should not require lookups and other advanced services, since they are basically **immutable**. We should probably go in this direction, but this might require breaking changes, which are not allowed in 2.x.
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Re: [I] Exception thrown in class annotated with @Plugin that uses a logger [logging-log4j2]
Posted by "ppkarwasz (via GitHub)" <gi...@apache.org>.
ppkarwasz closed issue #3240: Exception thrown in class annotated with @Plugin that uses a logger
URL: https://github.com/apache/logging-log4j2/issues/3240
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