Make `StatusLogger` self-contained and testable #2249

vy · 2024-01-25T21:33:21Z

Motivated by #2204 and making log4j-api-2.x adaptable by Log4j 3, this work revamps the StatusLogger to make it self-contained and testable. Noteworthy changes are as follows:

Simplifications and improvements for self-contained implementation

Dependencies on PropertiesUtil and LoaderUtil are eliminated. To do so, simple system property and resource from classpath readers are implemented. See the new StatusLogger.Config class.
Dependency on SimpleLogger is eliminated. The default listener is fixed to a StatusConsoleListener which dumps StatusData#getFormattedStatus() output to a PrintStream.
[behavioural change] StatusConfiguration does not create a new StatusListener each time anymore. That is, there will not be a dedicated StatusConsoleListener for every each LoggerContext. Existing behaviour was already problematic:
- Each StatusConfiguration created was resetting the StatusLogger listener level (hence, last one always wins)
- Created StatusConsoleListeners weren't cleaned up
- Even though there was a dedicated listener for each LoggerContext, there is always a single StatusLogger, defeating the purpose of per-LoggerContext listeners
Hence, we embraced a simpler model: There is one default StatusConsoleListener for the StatusLogger singleton. If user overrides the StatusLogger configuration in a log4j2.xml, last read configuration will be the effective one.
Several StatusLogger javadocs are rewritten.
LowLevelLogUtil is removed.
AbstractLogger doesn't act on log4j2.messageFactory and log4j2.flowMessageFactory properties anymore; its message and flow message factories are fixed to ParameterizedMessageFactory and DefaultFlowMessageFactory, respectively. This was necessary to avoid cyclic instantiation: PropertiesUtil is using StatusLogger, which extends AbstractLogger, which indirectly reaches back to PropertiesUtil for these two functionalities removed.

Testing-related changes

StatusLogger is made extendable (to enable mocking/spying)
StatusLogger static instance is made replaceable (to enable substituting the implementation for tests)
Leveraging these, @UsingStatusLoggerMock introduced

TODO

Introduce log4j2.messageFactory and log4j2.flowMessageFactory properties back
Update docs
Fix last remaining failing tests (already fixed some)
Check if there are any refactoring opportunities for @UsingStatusListener

Review kit

Start with reviewing changes in o.a.l.l.status package: StatusLogger, StatusData, StatusConsoleListener, etc.
Review StatusConfiguration
Review o.a.l.l.test.junit.StatusLoggerMockExtension to see testing conveniences
Review the rest

rgoers · 2024-01-25T21:55:18Z

I will go through this as I can. It might take a couple of days depending on my available time. However, the description of the solution above seems to aim right on target.

ppkarwasz

This looks almost ready.

Remark the PropertiesUtil.Environment does not log anything about broken property sources to prevent a recursive initialization. Now we can start logging again.

log4j-api-test/src/main/java/org/apache/logging/log4j/test/junit/UsingStatusLoggerMock.java

log4j-api-test/src/main/java/org/apache/logging/log4j/test/junit/package-info.java

log4j-api/src/main/java/org/apache/logging/log4j/status/StatusConsoleListener.java

log4j-api/src/main/java/org/apache/logging/log4j/status/StatusLogger.java

log4j-api/src/main/java/org/apache/logging/log4j/status/StatusData.java

log4j-api/src/main/java/org/apache/logging/log4j/status/StatusLogger.java

jvz

I like this approach so far!

vy · 2024-01-29T09:35:10Z

@ppkarwasz, I have introduced the fallback listener concept back in cd3fadb. Would you mind reviewing it, please?

log4j-core/src/main/java/org/apache/logging/log4j/core/jmx/StatusLoggerAdmin.java

ppkarwasz

LGTM

This reverts commit f3fa918.

`[email protected]` requires the sender to have an `@apache.org` address. Not all PMC members have this configured, this adds yet another step to the release process and yet another condition to hold in the RM machine, and people are not willing to drop this requirement[1]. [1] https://lists.apache.org/thread/jc7o25gxx9w3y3xq51kwbmcbz62cwkb2

As per discussion[1], nested logging is not an official feature. Hence, when it is broken, the build should not fail. [1] https://lists.apache.org/thread/gnwjw7sfhxogb7c70rqr4t0v6yh4px02

Nested logging is not an officially supported feature[1]. Tests should not rely on them. [1] https://lists.apache.org/thread/gnwjw7sfhxogb7c70rqr4t0v6yh4px02

log4j-api/src/main/java/org/apache/logging/log4j/status/StatusConsoleListener.java

lauredogit · 2024-02-23T09:16:31Z

Hi,
This change caused an issue when running on Java 8 and having configured a DateFormat for the StatusLogger (e.g. via log4j2.StatusLogger.DateFormat).

It will cause a StackOverflowError such as:

Caused by: java.lang.StackOverflowError
	at org.apache.logging.log4j.message.ParameterFormatter.analyzePattern(ParameterFormatter.java:93)
	at org.apache.logging.log4j.message.ParameterizedMessage.<init>(ParameterizedMessage.java:142)
	at org.apache.logging.log4j.message.ParameterizedMessage.<init>(ParameterizedMessage.java:176)
	at org.apache.logging.log4j.message.ParameterizedNoReferenceMessageFactory.newMessage(ParameterizedNoReferenceMessageFactory.java:105)
	at org.apache.logging.log4j.message.AbstractMessageFactory.newMessage(AbstractMessageFactory.java:103)
	at org.apache.logging.log4j.spi.AbstractLogger.logMessage(AbstractLogger.java:2686)
	at org.apache.logging.log4j.spi.AbstractLogger.logIfEnabled(AbstractLogger.java:2460)
	at org.apache.logging.log4j.spi.AbstractLogger.warn(AbstractLogger.java:3674)
	at org.apache.logging.log4j.spi.AbstractLogger.handleLogMessageException(AbstractLogger.java:2927)
	at org.apache.logging.log4j.spi.AbstractLogger.tryLogMessage(AbstractLogger.java:2909)
	at org.apache.logging.log4j.spi.AbstractLogger.logMessageTrackRecursion(AbstractLogger.java:2859)
	at org.apache.logging.log4j.spi.AbstractLogger.logMessageSafely(AbstractLogger.java:2841)
	at org.apache.logging.log4j.spi.AbstractLogger.logMessage(AbstractLogger.java:2687)
	at org.apache.logging.log4j.spi.AbstractLogger.logIfEnabled(AbstractLogger.java:2460)
	at org.apache.logging.log4j.spi.AbstractLogger.warn(AbstractLogger.java:3674)
	at org.apache.logging.log4j.spi.AbstractLogger.handleLogMessageException(AbstractLogger.java:2927)

which is caused by

java.time.temporal.UnsupportedTemporalTypeException: Unsupported field: YearOfEra
        at java.time.Instant.getLong(Instant.java:603)
        at java.time.format.DateTimePrintContext.getValue(DateTimePrintContext.java:298)
        at java.time.format.DateTimeFormatterBuilder$NumberPrinterParser.format(DateTimeFormatterBuilder.java:2551)
        at java.time.format.DateTimeFormatterBuilder$CompositePrinterParser.format(DateTimeFormatterBuilder.java:2190)
        at java.time.format.DateTimeFormatter.formatTo(DateTimeFormatter.java:1746)
        at java.time.format.DateTimeFormatter.format(DateTimeFormatter.java:1720)
        at org.apache.logging.log4j.status.StatusData.getFormattedStatus(StatusData.java:170)
        at org.apache.logging.log4j.status.StatusConsoleListener.log(StatusConsoleListener.java:138)
        at org.apache.logging.log4j.status.StatusLogger.notifyListener(StatusLogger.java:555)
        at org.apache.logging.log4j.status.StatusLogger.notifyListeners(StatusLogger.java:549)
        at org.apache.logging.log4j.status.StatusLogger.logMessage(StatusLogger.java:526)
        at org.apache.logging.log4j.spi.AbstractLogger.log(AbstractLogger.java:2812)
        at org.apache.logging.log4j.spi.AbstractLogger.tryLogMessage(AbstractLogger.java:2906)
        at org.apache.logging.log4j.spi.AbstractLogger.logMessageTrackRecursion(AbstractLogger.java:2859)
        at org.apache.logging.log4j.spi.AbstractLogger.logMessageSafely(AbstractLogger.java:2841)
        at org.apache.logging.log4j.spi.AbstractLogger.logMessage(AbstractLogger.java:2620)
        at org.apache.logging.log4j.spi.AbstractLogger.logIfEnabled(AbstractLogger.java:2567)
        at org.apache.logging.log4j.spi.AbstractLogger.warn(AbstractLogger.java:3469)

because in org.apache.logging.log4j.status.StatusLogger.Config#readInstantFormatter, the code is merely

logging-log4j2/log4j-api/src/main/java/org/apache/logging/log4j/status/StatusLogger.java

Lines 252 to 255 in f05864d

    
           private static DateTimeFormatter readInstantFormatter(final Properties fileProvidedProperties) { 
        
               final String format = readProperty(fileProvidedProperties, STATUS_DATE_FORMAT); 
        
               return format != null ? DateTimeFormatter.ofPattern(format) : null; 
        
           }

with only DateTimeFormatter.ofPattern(format)

This works on Java 11, but on Java 8, it breaks as in https://stackoverflow.com/questions/25229124/unsupportedtemporaltypeexception-when-formatting-instant-to-string

A very simple fix is to use instead

        private static DateTimeFormatter readInstantFormatter(final Properties fileProvidedProperties) {
            final String format = readProperty(fileProvidedProperties, STATUS_DATE_FORMAT);
            return format != null ? DateTimeFormatter.ofPattern(format).withZone(ZoneId.systemDefault()) : null;
        }

Hence using
DateTimeFormatter.ofPattern(format).withZone(ZoneId.systemDefault())

vy · 2024-02-23T16:41:26Z

@lauredogit, thanks so much for the report. I will submit a fix. We are considering a 2.23.1 release sometime soon, maybe next week?

lauredogit · 2024-02-23T17:45:48Z

Perfect, thanks!

I think there are 2 distinct issues at play.

The easy one to fix is the actual UnsupportedTemporalTypeException on Java 8, which will be fixed easily by adding the ".withZone(ZoneId.systemDefault())".

However, the other issue is that having such an exception thrown by the StatusLogger was causing a StackOverflowError...
and this was not mitigated by AbstractLogger.logMessageTrackRecursion().

This can be investigated later on, though.

ppkarwasz · 2024-02-23T19:03:58Z

Well, logMessageTrackRecursion only tracks recursion, it doesn't do anything about it. Other parts of the system like async logger read the recursion level (and log synchronously for example).

ppkarwasz · 2025-07-13T12:45:02Z

Hi @vy,

It looks like this change isn't mentioned in the 2.23.0 release notes, even though—if I recall correctly—it was one of the most significant enhancements in that version.

Notably, this change has an important (and, as I remember it, intentional) side effect for users of log4j-to-slf4j and log4j-to-jul: it disables message pooling via ReusableMessageFactory. This behavior aligns with the design of the target logging systems:

The default JUL implementation lacks GC-free features, and JBoss LogManager provides its own optimized log4j-to-jul integration.
Logback, the only native SLF4J implementation, also creates a new LoggingEvent object per log call.

So, disabling GC-free logging in these bridges was a deliberate decision—but one that should be clearly documented. Could you please update the release notes to reflect this?

Thanks!

vy · 2025-07-20T17:56:37Z

@ppkarwasz, you're right. I've submitted #3838 to address this. Would you mind reviewing, please?

Make StatusLogger self-contained and testable

94c813c

vy added api Affects the public API tests Pull requests or issues related to tests labels Jan 25, 2024

vy added this to the 2.23.0 milestone Jan 25, 2024

vy requested review from jvz, ppkarwasz and rgoers January 25, 2024 21:33

vy self-assigned this Jan 25, 2024

ppkarwasz reviewed Jan 25, 2024

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Extend UsingStatusLoggerMock with ExtensionContextAnchor

fd67e38

ppkarwasz reviewed Jan 26, 2024

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ppkarwasz reviewed Jan 26, 2024

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log4j-api/src/main/java/org/apache/logging/log4j/status/StatusLogger.java Show resolved Hide resolved

vy added 2 commits January 26, 2024 10:36

Speed-up isEnabled() by caching the least specific listener level

21a47ac

Merge remote-tracking branch 'origin/2.x' into 2.x-StatusLogger-revamp

cd8912d

jvz reviewed Jan 26, 2024

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log4j-api/src/main/java/org/apache/logging/log4j/status/StatusData.java Show resolved Hide resolved

jvz reviewed Jan 26, 2024

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log4j-api/src/main/java/org/apache/logging/log4j/status/StatusLogger.java Show resolved Hide resolved

jvz reviewed Jan 26, 2024

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jvz reviewed Jan 26, 2024

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jvz approved these changes Jan 26, 2024

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Bring the fallback StatusListener concept back

cd3fadb

vy added 2 commits January 29, 2024 10:36

Make StatusLogger() ctor private

f1e3e2f

Document unmodifiable collection usage

c4c941e

ppkarwasz reviewed Jan 29, 2024

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log4j-core/src/main/java/org/apache/logging/log4j/core/jmx/StatusLoggerAdmin.java Outdated Show resolved Hide resolved

vy added 4 commits January 29, 2024 10:59

Initialize the default StatusLogger instance lazy

3684a2e

Fix @Versions

2c01bcd

Fix Spotless issues

fdcb05b

Rework StatusLogger effective level

40cc721

ppkarwasz approved these changes Jan 29, 2024

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ppkarwasz and others added 15 commits January 30, 2024 20:15

Revert "Fix NPE in AsyncLoggerConfigDisruptor"

682604b

This reverts commit f3fa918.

Merge branch '2.x' into 2.x-StatusLogger-revamp

e0090d4

Merge remote-tracking branch 'origin/2.x' into 2.x-StatusLogger-revamp

e2e983f

Update auto-generated files

8632e09

Remove nested logging tests

73cd685

As per discussion[1], nested logging is not an official feature. Hence, when it is broken, the build should not fail. [1] https://lists.apache.org/thread/gnwjw7sfhxogb7c70rqr4t0v6yh4px02

Merge remote-tracking branch 'origin/2.x' into 2.x-StatusLogger-revamp

bfb5197

Remove QueueFullAsync* tests relying on nested logging

9720939

Nested logging is not an officially supported feature[1]. Tests should not rely on them. [1] https://lists.apache.org/thread/gnwjw7sfhxogb7c70rqr4t0v6yh4px02

Trim recently added public methods to StatusLogger

c0235e3

Deprecate buffering provided by StatusLogger

b8e490c

Match level comparison in StatusConsoleListener and StatusLogger

bfdbde4

Add getter for the fallback listener in StatusLogger

fab3f15

Merge remote-tracking branch 'origin/2.x' into 2.x-StatusLogger-revamp

9f7533f

Improve StatusLogger javadoc

4d43e82

Fix javadoc:javadoc failures

c48bb4f

ppkarwasz reviewed Feb 8, 2024

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log4j-api/src/main/java/org/apache/logging/log4j/status/StatusConsoleListener.java Show resolved Hide resolved

vy changed the title ~~Draft: Make StatusLogger self-contained and testable~~ Make StatusLogger self-contained and testable Feb 8, 2024

vy merged commit ce1a3a4 into 2.x Feb 8, 2024

vy deleted the 2.x-StatusLogger-revamp branch February 8, 2024 12:29

This was referenced Feb 8, 2024

[MS10] Log4j API generalization #1 #2273

Closed

Reset the fallback listener on StatusLogger#reset() #2280

Merged

vy mentioned this pull request Feb 23, 2024

Fix StatusLogger time-zone issues and stack overflow #2322

Merged

jamezp mentioned this pull request Aug 19, 2024

Bump org.jboss.logmanager:log4j2-jboss-logmanager from 1.1.2.Final to 2.0.1.Final quarkusio/quarkus#42559

Merged

Rassyan mentioned this pull request Sep 18, 2025

Upgrade to log4j 2.25.1 elastic/elasticsearch#132166

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Make StatusLogger self-contained and testable #2249

Make StatusLogger self-contained and testable #2249

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vy commented Jan 25, 2024

Simplifications and improvements for self-contained implementation

Testing-related changes

TODO

Review kit

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Make `StatusLogger` self-contained and testable #2249

Make `StatusLogger` self-contained and testable #2249

lauredogit commented Feb 23, 2024 •

edited by ppkarwasz

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