Hello, I have run into the same issue as documented in this Jira: https://jira.qos.ch/browse/LOGBACK-1421?page=com.atlassian.jira.plugin.syste... I notice most application threads are blocked with following stack trace. Looking at Jira, it seems fix for this was planned to be included as part of 1.3.0-alpha6 but I didn't find this release tag on Logback Github repo. Are there any plans to have a fix for this issue? I see we run into issue under high load. We run Java 11 on Linux RHEL 7. "ForkJoinPool.commonPool-worker-705" #29535 daemon prio=10 os_prio=0 cpu=11.37ms elapsed=343.90s tid=0x00007fd5dc197590 nid=0x2ad83 waiting for monitor entry [0x00007fccdadeb000] java.lang.Thread.State: BLOCKED (on object monitor) at ch.qos.logback.core.util.CachingDateFormatter.format(CachingDateFormatter.java:45) - waiting to lock <0x000008206586ad18> (a ch.qos.logback.core.util.CachingDateFormatter) at ch.qos.logback.classic.pattern.DateConverter.convert(DateConverter.java:61) at ch.qos.logback.classic.pattern.DateConverter.convert(DateConverter.java:23) at ch.qos.logback.core.pattern.FormattingConverter.write(FormattingConverter.java:36) at ch.qos.logback.core.pattern.PatternLayoutBase.writeLoopOnConverters(PatternLayoutBase.java:115) at ch.qos.logback.classic.PatternLayout.doLayout(PatternLayout.java:141) at ch.qos.logback.classic.PatternLayout.doLayout(PatternLayout.java:39) at ch.qos.logback.core.encoder.LayoutWrappingEncoder.encode(LayoutWrappingEncoder.java:115) at ch.qos.logback.core.OutputStreamAppender.subAppend(OutputStreamAppender.java:230) at ch.qos.logback.core.rolling.RollingFileAppender.subAppend(RollingFileAppender.java:235) at ch.qos.logback.core.OutputStreamAppender.append(OutputStreamAppender.java:102) at ch.qos.logback.core.UnsynchronizedAppenderBase.doAppend(UnsynchronizedAppenderBase.java:84) at ch.qos.logback.core.spi.AppenderAttachableImpl.appendLoopOnAppenders(AppenderAttachableImpl.java:51) at ch.qos.logback.classic.Logger.appendLoopOnAppenders(Logger.java:270) at ch.qos.logback.classic.Logger.callAppenders(Logger.java:257) at ch.qos.logback.classic.Logger.buildLoggingEventAndAppend(Logger.java:421) at ch.qos.logback.classic.Logger.filterAndLog_0_Or3Plus(Logger.java:383) at ch.qos.logback.classic.Logger.info(Logger.java:579) Thank you for your help! Prabhash Rathore