[logback-dev] [JIRA] (LOGBACK-1027) Circular Referenced Suppressed Exception Throws StackOverflowError

QOS.CH (JIRA) Fri, 05 Jun 2020 08:38:27 -0700

Title: Message Title

Eclipse Jetty hit this issue as well.
Looks like OpenJDK 8u252 and OpenJDK 11.0.7 both have circular suppressed exception loops within their TLS layer.

Circular Exception references are supported by the JVM's own Throwable.printStackTrace(), so we feel that logback should support them as well. (note: this is only a bug on logback, other slf4j implementations do not have this issue).

In Jetty we worked out a hack with our community for a custom logback TurboFilter that can be used to hack around this bug in logback.

 
                                                                package org.eclipse.jetty.logbackhack;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.HashSet;
import java.util.Set;

import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.turbo.TurboFilter;
import ch.qos.logback.core.spi.FilterReply;
import org.slf4j.LoggerFactory;
import org.slf4j.Marker;

public class RecursiveThrowableFixTurboFilter extends TurboFilter
{
    public static void init()
    {
        ch.qos.logback.classic.Logger rootLogger = (ch.qos.logback.classic.Logger)LoggerFactory.getLogger(org.slf4j.Logger.ROOT_LOGGER_NAME);
        rootLogger.getLoggerContext().addTurboFilter(new RecursiveThrowableFixTurboFilter());
    }

    @Override
    public FilterReply decide(Marker marker, Logger logger, Level level, String format, Object[] params, Throwable cause)
    {
        if (hasRecursiveThrowableReference(cause, null))
        {
            int locationAwareLoggerInteger = Level.toLocationAwareLoggerInteger(level);
            logger.log(marker, logger.getName(), locationAwareLoggerInteger, format, params, new SafeException(cause));
            return FilterReply.DENY;
        }

        return FilterReply.NEUTRAL;
    }

    private boolean hasRecursiveThrowableReference(Throwable cause, Set<Throwable> seen)
    {
        if (cause == null)
            return false;

        if (seen == null)
        {
            seen = new HashSet<>();
        }
        else if (!seen.add(cause))
        {
            return true;
        }

        for (Throwable suppressed : cause.getSuppressed())
        {
            if (hasRecursiveThrowableReference(suppressed, seen))
            {
                return true;
            }
        }
        return hasRecursiveThrowableReference(cause.getCause(), seen);
    }

    public static String toStackTrace(Throwable cause)
    {
        try (StringWriter sw = new StringWriter();
             PrintWriter pw = new PrintWriter(sw))
        {
            cause.printStackTrace(pw);
            return sw.toString();
        }
        catch (IOException e)
        {
            return "Unable to produce Stacktrace for " + cause;
        }
    }

    public static class SafeException extends RuntimeException
    {
        public SafeException(Throwable cause)
        {
            super(toStackTrace(cause));
        }
    }
}
 
                                                            

We would appreciate a fix in the logback 1.2.x series (seeing as logback 1.3.x is all about radical API changes for slf4j 2.x)

If the existing PR at https://github.com/qos-ch/logback/pull/399 isn't suitable. Let us know, and we'll submit our own PR for a solution for this.

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[logback-dev] [JIRA] (LOGBACK-1027) Circular Referenced Suppressed Exception Throws StackOverflowError

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