[jira] [Created] (LOG4J2-2449) ClassCastException with ContextDataInjector override, SortedArrayStringMap, and Context Map Lookup

["Kristen Kozak (JIRA)" <ji...@apache.org>]

Kristen Kozak created LOG4J2-2449:
-------------------------------------

             Summary: ClassCastException with ContextDataInjector override, SortedArrayStringMap, and Context Map Lookup
                 Key: LOG4J2-2449
                 URL: https://issues.apache.org/jira/browse/LOG4J2-2449
             Project: Log4j 2
          Issue Type: Bug
          Components: Lookups, Plugins
    Affects Versions: 2.11.1
         Environment: Linux, Java 8
            Reporter: Kristen Kozak


I am working on a library for inserting opencensus-java distributed tracing data into Log4j LogEvents.  I used a custom ContextDataInjector that reads the current tracing data and inserts it into the context data.  The context data must be returned as a StringMap ([https://logging.apache.org/log4j/2.0/log4j-api/apidocs/org/apache/logging/log4j/util/SortedArrayStringMap.html#putValue(java.lang.String,%20java.lang.Object)|https://logging.apache.org/log4j/2.0/log4j-api/apidocs/org/apache/logging/log4j/util/SortedArrayStringMap.html#putValue(java.lang.String,%20java.lang.Object)]).] ), so I used a SortedArrayStringMap.  I used SortedArrayStringMap.putValue(String, Object) to insert objects for lazily formatting tracing data, for example, an object with a toString() method that formats a trace ID as lowercase base 16 ([https://github.com/census-instrumentation/opencensus-java/blob/eabbc41366340e2833295894bc0f4d5dcddba1dd/contrib/log_correlation/log4j2/src/main/java/io/opencensus/contrib/logcorrelation/log4j2/ContextDataUtils.java#L151-L162] ).  I noticed that multiple Log4j code paths call toString() on the values when the String is finally needed.  However, when I tried using a JsonLayout and Context Map Lookup to put tracing data into a JSON structure, I got a ClassCastException, because the values were only cast to Strings.

The original issue for the ClassCastException in opencensus-java is [https://github.com/census-instrumentation/opencensus-java/issues/1436|https://github.com/census-instrumentation/opencensus-java/issues/1436.] .  The error is:

{{2018-09-14 20:59:52,690 main ERROR An exception occurred processing Appender File java.lang.ClassCastException: io.opencensus.contrib.logcorrelation.log4j2.ContextDataUtils$TraceIdToLowerBase16Formatter cannot be cast to java.lang.String}}
{{ at org.apache.logging.log4j.core.lookup.ContextMapLookup.lookup(ContextMapLookup.java:58)}}
{{ at org.apache.logging.log4j.core.lookup.Interpolator.lookup(Interpolator.java:188)}}
{{ at org.apache.logging.log4j.core.lookup.StrSubstitutor.resolveVariable(StrSubstitutor.java:1060)}}
{{ at org.apache.logging.log4j.core.lookup.StrSubstitutor.substitute(StrSubstitutor.java:982)}}
{{ at org.apache.logging.log4j.core.lookup.StrSubstitutor.substitute(StrSubstitutor.java:878)}}
{{ at org.apache.logging.log4j.core.lookup.StrSubstitutor.replace(StrSubstitutor.java:433)}}
{{ at org.apache.logging.log4j.core.layout.AbstractJacksonLayout.resolveAdditionalFields(AbstractJacksonLayout.java:292)}}
{{ at org.apache.logging.log4j.core.layout.AbstractJacksonLayout.wrapLogEvent(AbstractJacksonLayout.java:274)}}
{{ at org.apache.logging.log4j.core.layout.AbstractJacksonLayout.toSerializable(AbstractJacksonLayout.java:304)}}
{{ at org.apache.logging.log4j.core.layout.JsonLayout.toSerializable(JsonLayout.java:291)}}
{{ at org.apache.logging.log4j.core.layout.AbstractJacksonLayout.toSerializable(AbstractJacksonLayout.java:255)}}
{{ at org.apache.logging.log4j.core.layout.JsonLayout.toSerializable(JsonLayout.java:68)}}
{{ at org.apache.logging.log4j.core.layout.AbstractJacksonLayout.toSerializable(AbstractJacksonLayout.java:44)}}
{{ at org.apache.logging.log4j.core.layout.AbstractStringLayout.toByteArray(AbstractStringLayout.java:304)}}
{{ at org.apache.logging.log4j.core.layout.AbstractLayout.encode(AbstractLayout.java:210)}}
{{ at org.apache.logging.log4j.core.layout.AbstractLayout.encode(AbstractLayout.java:37)}}
{{ at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.directEncodeEvent(AbstractOutputStreamAppender.java:177)}}
{{ at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.tryAppend(AbstractOutputStreamAppender.java:170)}}
{{ at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.append(AbstractOutputStreamAppender.java:161)}}
{{ at org.apache.logging.log4j.core.config.AppenderControl.tryCallAppender(AppenderControl.java:156)}}
{{ at org.apache.logging.log4j.core.config.AppenderControl.callAppender0(AppenderControl.java:129)}}
{{ at org.apache.logging.log4j.core.config.AppenderControl.callAppenderPreventRecursion(AppenderControl.java:120)}}
{{ at org.apache.logging.log4j.core.config.AppenderControl.callAppender(AppenderControl.java:84)}}
{{ at org.apache.logging.log4j.core.config.LoggerConfig.callAppenders(LoggerConfig.java:464)}}
{{ at org.apache.logging.log4j.core.config.LoggerConfig.processLogEvent(LoggerConfig.java:448)}}
{{ at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:431)}}
{{ at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:406)}}
{{ at org.apache.logging.log4j.core.config.AwaitCompletionReliabilityStrategy.log(AwaitCompletionReliabilityStrategy.java:63)}}
{{ at org.apache.logging.log4j.core.Logger.logMessage(Logger.java:146)}}
{{ at org.apache.logging.log4j.spi.AbstractLogger.tryLogMessage(AbstractLogger.java:2170)}}
{{ at org.apache.logging.log4j.spi.AbstractLogger.logMessageTrackRecursion(AbstractLogger.java:2125)}}
{{ at org.apache.logging.log4j.spi.AbstractLogger.logMessageSafely(AbstractLogger.java:2108)}}
{{ at org.apache.logging.log4j.spi.AbstractLogger.logMessage(AbstractLogger.java:2002)}}
{{ at org.apache.logging.log4j.spi.AbstractLogger.logIfEnabled(AbstractLogger.java:1974)}}
{{ at org.apache.logging.log4j.spi.AbstractLogger.warn(AbstractLogger.java:2624)}}
{{ at io.opencensus.contrib.logcorrelation.log4j.demo.OpenCensusLog4jLogCorrelationDemo.doWork(OpenCensusLog4jLogCorrelationDemo.java:60)}}
{{ at io.opencensus.contrib.logcorrelation.log4j.demo.OpenCensusLog4jLogCorrelationDemo.createSampledTrace(OpenCensusLog4jLogCorrelationDemo.java:50)}}
{{ at io.opencensus.contrib.logcorrelation.log4j.demo.OpenCensusLog4jLogCorrelationDemo.main(OpenCensusLog4jLogCorrelationDemo.java:44)}}

 

I'm not sure whether this is a bug or StringMap is not meant to hold lazy formatting objects.



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