FileHandler generate extra logs files when original log is locked

Question

I need generate one log file by each application installed and running on websphere application server 9. I use JUL for generate log's file. My solution was create a especific Class thas inherits from FileHandler and set logs properties by a config file.

This is my code:

//Read config file
LogManager.getLogManager().readConfiguration(LoggerJUL.class.getResourceAsStream("/Logger.properties"));
//Add handler to logger
Logger.getLogger(clazz)).addHandler(new PersonalFileHandler());

PersonalFileHandler extends FileHandler, and properties are set by configure method on FileHandler class on runtime.

In this way i achieve make one log file by application running over Websphere, without overwriting the destination of the server log.

Although I achieve part of the objective, extra files are generated if the original log file is locked, same like this: testLogs.log.0, testLogs.log.1, testLogs.log.0.1, etc. I read many suggestions and solutions, but i can't stop this isue. Any suggestions ?

handlers = com.mucam.xxxx.PersonalFileHandler
# Set the default formatter to be the simple formatter
com.mucam.xxxx.PersonalFileHandler.formatter = java.util.logging.SimpleFormatter
# Write the log files to some file pattern
com.mucam.xxxx.PersonalFileHandler.pattern = C:/Users/pmendez/Documents/Log/testLogs.log
# Limit log file size to 5 Kb
com.mucam.xxxx.PersonalFileHandler.limit = 5000
# Keep 10 log files
com.mucam.xxxx.PersonalFileHandler.count = 10
#Customize the SimpleFormatter output format 
java.util.logging.SimpleFormatter.format = %d{ISO8601} [%t] %-5p %c %x - %m%n
#Append to existing file
com.mucam.xxxx.PersonalFileHandler.append = true

jmehrens · Accepted Answer · 2019-08-28T18:55:01.253

Although I achieve part of the objective, extra files are generated if the original log file is locked, same like this: testLogs.log.0, testLogs.log.1, testLogs.log.0.1, etc. I read many suggestions and solutions, but i can't stop this isue. Any suggestions ?

Since your count is set to 10 you need to specify the %g pattern to log the generation.

com.mucam.xxxx.PersonalFileHandler.pattern = C:/Users/pmendez/Documents/Log/testLogs%g.log

The pattern is absolute path so if you create multiple filehandlers it will resolve conflicts by appending unique number to the end. This is specified by the %u pattern. So if you want to move where the integer is placed in the file name you specify the %u token in the pattern.

This also means that you are creating multiple instances of your custom file handler and they are not being closed. If you want to control the number of files you either need to control the number of PersonalFileHandler you create and or share a reference to singleton PersonalFileHandler. Otherwise you need to make sure that if you explicitly create a PersonalFileHandler that you are explicit closing that PersonalFileHandler before you create a second new PersonalFileHandler.

Loggers are subject to garbage collection. The line:

Logger.getLogger(clazz).addHandler(new PersonalFileHandler());

Is subject to garbage collection unless the code elsewhere as already pinned that logger in memory. This can cause log files to be created, locked, and empty.

FileHandler generate extra logs files when original log is locked

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