quaff opened a new issue, #2893: URL: https://github.com/apache/logging-log4j2/issues/2893
## Description Log operation is blocked when the RingBuffer is full, then waiting for appender to consume LogEvent's from the RingBuffer, but the appender itself may operate logging before the consumption to trigger deadlock. Here is my actual case in production, I'm using Kafka appender, the Kafka client logging caused deadlock, see [TransactionManager.java](https://github.com/apache/kafka/blob/f9e30289d96b6c096c2bad44d714200e4c34cc04/clients/src/main/java/org/apache/kafka/clients/producer/internals/TransactionManager.java#L503) ``` "kafka-producer-network-thread | producer-1" #44 daemon prio=5 os_prio=0 tid=0x00007f468310c800 nid=0x256255 waiting for monitor entry [0x00007f467ad6c000] java.lang.Thread.State: BLOCKED (on object monitor) at org.apache.logging.log4j.core.async.AsyncLoggerDisruptor.enqueueLogMessageWhenQueueFull(AsyncLoggerDisruptor.java:246) - waiting to lock <0x0000000701070490> (a java.lang.Object) at org.apache.logging.log4j.core.async.AsyncLogger.handleRingBufferFull(AsyncLogger.java:246) at org.apache.logging.log4j.core.async.AsyncLogger.publish(AsyncLogger.java:230) at org.apache.logging.log4j.core.async.AsyncLogger.logWithThreadLocalTranslator(AsyncLogger.java:202) at org.apache.logging.log4j.core.async.AsyncLogger.access$100(AsyncLogger.java:67) at org.apache.logging.log4j.core.async.AsyncLogger$1.log(AsyncLogger.java:157) at org.apache.logging.log4j.core.async.AsyncLogger.logMessage(AsyncLogger.java:130) at org.apache.logging.slf4j.Log4jLogger.log(Log4jLogger.java:378) at org.apache.kafka.common.utils.LogContext$LocationAwareKafkaLogger.writeLog(LogContext.java:434) at org.apache.kafka.common.utils.LogContext$LocationAwareKafkaLogger.info(LogContext.java:387) at org.apache.kafka.clients.producer.internals.TransactionManager.setProducerIdAndEpoch(TransactionManager.java:505) at org.apache.kafka.clients.producer.internals.TransactionManager.bumpIdempotentProducerEpoch(TransactionManager.java:542) at org.apache.kafka.clients.producer.internals.TransactionManager.bumpIdempotentEpochAndResetIdIfNeeded(TransactionManager.java:559) - locked <0x00000007016c0898> (a org.apache.kafka.clients.producer.internals.TransactionManager) at org.apache.kafka.clients.producer.internals.Sender.runOnce(Sender.java:330) at org.apache.kafka.clients.producer.internals.Sender.run(Sender.java:247) at java.lang.Thread.run(Thread.java:748) ``` ``` "http-nio-8080-exec-273" #3682 daemon prio=5 os_prio=0 tid=0x00007f465b422800 nid=0x2908d3 runnable [0x00007f4648b48000] java.lang.Thread.State: TIMED_WAITING (parking) at sun.misc.Unsafe.park(Native Method) at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:338) at com.lmax.disruptor.MultiProducerSequencer.next(MultiProducerSequencer.java:136) at com.lmax.disruptor.MultiProducerSequencer.next(MultiProducerSequencer.java:105) at com.lmax.disruptor.RingBuffer.publishEvent(RingBuffer.java:465) at com.lmax.disruptor.dsl.Disruptor.publishEvent(Disruptor.java:331) at org.apache.logging.log4j.core.async.AsyncLoggerDisruptor.enqueueLogMessageWhenQueueFull(AsyncLoggerDisruptor.java:247) - locked <0x0000000701070490> (a java.lang.Object) at org.apache.logging.log4j.core.async.AsyncLogger.handleRingBufferFull(AsyncLogger.java:246) at org.apache.logging.log4j.core.async.AsyncLogger.publish(AsyncLogger.java:230) at org.apache.logging.log4j.core.async.AsyncLogger.logWithThreadLocalTranslator(AsyncLogger.java:225) at org.apache.logging.log4j.core.async.AsyncLogger.access$000(AsyncLogger.java:67) at org.apache.logging.log4j.core.async.AsyncLogger$1.log(AsyncLogger.java:152) at org.apache.logging.log4j.core.async.AsyncLogger.log(AsyncLogger.java:136) at org.apache.logging.log4j.spi.AbstractLogger.tryLogMessage(AbstractLogger.java:2168) at org.apache.logging.log4j.spi.AbstractLogger.logMessageTrackRecursion(AbstractLogger.java:2122) at org.apache.logging.log4j.spi.AbstractLogger.logMessageSafely(AbstractLogger.java:2105) at org.apache.logging.log4j.spi.AbstractLogger.logMessage(AbstractLogger.java:1997) at org.apache.logging.log4j.spi.AbstractLogger.logIfEnabled(AbstractLogger.java:1862) at org.apache.logging.slf4j.Log4jLogger.info(Log4jLogger.java:185) ``` ## Proposal The issue is not Kafka specified, log4j should discard `LogEvent` from appenders if the underlying `RingBuffer` is full. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
