Configuration:
<appender name="DebugLog" class="ch.qos.logback.core.rolling.RollingFileAppender">
<!--See also http://logback.qos.ch/manual/appenders.html#RollingFileAppender-->
<file>c:/log/debug.log</file>
<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
<!-- rollover daily -->
<fileNamePattern>c:/log/debug-old-%d

{yyyy-MM-dd}

.%i.log</fileNamePattern>
<maxHistory>3</maxHistory>
<timeBasedFileNamingAndTriggeringPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
<maxFileSize>10KB</maxFileSize>
</timeBasedFileNamingAndTriggeringPolicy>
</rollingPolicy>
<encoder>
<pattern>%date

{ISO8601}

%-5level [%thread] %logger

{30}

:%line - %msg%n</pattern>
</encoder>
</appender>

Steps to reproduce:
1. Start the application
2. debug.log was created.
3. let run, until periodscounter reaches 10 or more (or prepare the files), e.g.

c:\log\debug-old-2010-08-10.0.log
c:\log\debug-old-2010-08-10.1.log
c:\log\debug-old-2010-08-10.10.log
c:\log\debug-old-2010-08-10.11.log
c:\log\debug-old-2010-08-10.12.log
c:\log\debug-old-2010-08-10.2.log
c:\log\debug-old-2010-08-10.3.log
c:\log\debug-old-2010-08-10.4.log
c:\log\debug-old-2010-08-10.5.log
c:\log\debug-old-2010-08-10.6.log
c:\log\debug-old-2010-08-10.7.log
c:\log\debug-old-2010-08-10.8.log
c:\log\debug-old-2010-08-10.9.log

4. restart the application
5. log to base.log
6. yyyy-MM-dd.10.log was (re-)created on rollover, overwrite the previous yyyy-MM-dd.10.log. Logging messages are lost.

It looks like the root cause is the (reversed) sorting via filenames in method

ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP.computeCurrentPeriodsHighestCounterValue(String)

FileFilterUtil.reverseSortFileArrayByName(matchingFileArray);
currentPeriodsCounter = FileFilterUtil.extractCounter(matchingFileArray[0], stemRegex);

because the input file array looks like:

c:\log\debug-old-2010-08-10.0.log
c:\log\debug-old-2010-08-10.1.log
c:\log\debug-old-2010-08-10.10.log
c:\log\debug-old-2010-08-10.11.log
c:\log\debug-old-2010-08-10.12.log
c:\log\debug-old-2010-08-10.2.log
c:\log\debug-old-2010-08-10.3.log
c:\log\debug-old-2010-08-10.4.log
c:\log\debug-old-2010-08-10.5.log
c:\log\debug-old-2010-08-10.6.log
c:\log\debug-old-2010-08-10.7.log
c:\log\debug-old-2010-08-10.8.log
c:\log\debug-old-2010-08-10.9.log

and in reversed order:

c:\log\debug-old-2010-08-10.9.log
c:\log\debug-old-2010-08-10.8.log
c:\log\debug-old-2010-08-10.7.log
c:\log\debug-old-2010-08-10.6.log
c:\log\debug-old-2010-08-10.5.log
c:\log\debug-old-2010-08-10.4.log
c:\log\debug-old-2010-08-10.3.log
c:\log\debug-old-2010-08-10.2.log
c:\log\debug-old-2010-08-10.12.log
c:\log\debug-old-2010-08-10.11.log
c:\log\debug-old-2010-08-10.10.log
c:\log\debug-old-2010-08-10.1.log
c:\log\debug-old-2010-08-10.0.log

then the wrong index 9 of the first file is used!

Suggestion for solution:

Get all indizes and use the highest.

for example:

void computeCurrentPeriodsHighestCounterValue(final String stemRegex) {
File file = new File(getCurrentPeriodsFileNameWithoutCompressionSuffix());

File parentDir = file.getParentFile();
File[] matchingFileArray = FileFilterUtil
.filesInFolderMatchingStemRegex(parentDir, stemRegex);

if (matchingFileArray == null || matchingFileArray.length == 0)

{ currentPeriodsCounter = 0; return; }

// FileFilterUtil.reverseSortFileArrayByName(matchingFileArray);
// currentPeriodsCounter = FileFilterUtil.extractCounter(matchingFileArray[0], stemRegex);

for (File logFile : matchingFileArray) {
int aPeriodCounter = FileFilterUtil.extractCounter(logFile, stemRegex);
if (aPeriodCounter > currentPeriodsCounter)

{ currentPeriodsCounter = aPeriodCounter; }

}

if (tbrp.getParentsRawFileProperty() != null)

{ currentPeriodsCounter++; }

}