vy commented on code in PR #2581: URL: https://github.com/apache/logging-log4j2/pull/2581#discussion_r1602715319
########## src/site/antora/modules/ROOT/pages/manual/index.adoc: ########## @@ -16,122 +16,57 @@ //// = Manual -== Welcome to Log4j! - -Almost every large application includes its own logging or tracing API. -In conformance with this rule, the E.U. http://www.semper.org[SEMPER] -project decided to write its own tracing API. This was in early 1996. -After countless enhancements, several incarnations and much work that -API has evolved to become log4j, a popular logging package for Java. The -package is distributed under the https://www.apache.org/licenses/LICENSE-2.0[Apache Software -License], a fully-fledged open source license certified by the -http://www.opensource.org[open source] initiative. The latest log4j -version, including full-source code, class files and documentation can -be found at -https://logging.apache.org/log4j/2.x/index.html[*https://logging.apache.org/log4j/2.x/index.html*]. - -Inserting log statements into code is a low-tech method for debugging -it. It may also be the only way because debuggers are not always -available or applicable. This is usually the case for multithreaded -applications and distributed applications at large. - -Experience indicates that logging was an important component of the -development cycle. It offers several advantages. It provides precise -_context_ about a run of the application. Once inserted into the code, -the generation of logging output requires no human intervention. -Moreover, log output can be saved in persistent medium to be studied at -a later time. In addition to its use in the development cycle, a -sufficiently rich logging package can also be viewed as an auditing -tool. - -As Brian W. Kernighan and Rob Pike put it in their truly excellent book -_"The Practice of Programming":_ - -____ -As personal choice, we tend not to use debuggers beyond getting a stack -trace or the value of a variable or two. One reason is that it is easy -to get lost in details of complicated data structures and control flow; -we find stepping through a program less productive than thinking harder -and adding output statements and self-checking code at critical places. -Clicking over statements takes longer than scanning the output of -judiciously-placed displays. It takes less time to decide where to put -print statements than to single-step to the critical section of code, -even assuming we know where that is. More important, debugging -statements stay with the program; debugging sessions are transient. -____ - -Logging does have its drawbacks. It can slow down an application. If too -verbose, it can cause scrolling blindness. To alleviate these concerns, -log4j is designed to be reliable, fast and extensible. Since logging is -rarely the main focus of an application, the log4j API strives to be -simple to understand and to use. - -== Log4j 2 - -Log4j 1 has been widely adopted and used in many applications. -However, through the years development on it has slowed down. It has -become more difficult to maintain due to its need to be compliant with -very old versions of Java and became -https://blogs.apache.org/foundation/entry/apache_logging_services_project_announces[End -of Life] in August 2015. Its alternative, SLF4J/Logback made many needed -improvements to the framework. So why bother with Log4j 2? Here are a -few of the reasons. - -1. Log4j 2 is designed to be usable as an audit logging framework. Both -Log4j 1.x and Logback will lose events while reconfiguring. Log4j 2 will -not. In Logback, exceptions in Appenders are never visible to the -application. In Log4j 2 Appenders can be configured to allow the -exception to percolate to the application. -2. Log4j 2 contains next-generation xref:manual/async.adoc[Asynchronous -Loggers] based on the https://lmax-exchange.github.io/disruptor/[LMAX -Disruptor library]. In multi-threaded scenarios Asynchronous Loggers -have 10 times higher throughput and orders of magnitude lower latency -than Log4j 1.x and Logback. -3. Log4j 2 is xref:manual/garbagefree.adoc[garbage free] for stand-alone -applications, and low garbage for web applications during steady state -logging. This reduces pressure on the garbage collector and can give -better response time performance. -4. Log4j 2 uses a xref:manual/plugins.adoc[Plugin system] that makes it -extremely easy to xref:manual/extending.adoc[extend the framework] by adding -new xref:manual/appenders.adoc[Appenders], xref:manual/filters.adoc[Filters], -xref:manual/layouts.adoc[Layouts], xref:manual/lookups.adoc[Lookups], and Pattern -Converters without requiring any changes to Log4j. -5. Due to the Plugin system configuration is simpler. Entries in the -configuration do not require a class name to be specified. -6. Support for xref:manual/customloglevels.adoc[custom log levels]. Custom log -levels can be defined in code or in configuration. -7. Support for xref:manual/api.adoc#LambdaSupport[lambda expressions]. Client -code running on Java 8 can use lambda expressions to lazily construct a -log message only if the requested log level is enabled. Explicit level -checks are not needed, resulting in cleaner code. -8. Support for xref:manual/messages.adoc[Message objects]. Messages allow -support for interesting and complex constructs to be passed through the -logging system and be efficiently manipulated. Users are free to create -their own `Message` types and write custom xref:manual/layouts.adoc[Layouts], -xref:manual/filters.adoc[Filters] and xref:manual/lookups.adoc[Lookups] to manipulate -them. -9. Log4j 1.x supports Filters on Appenders. Logback added TurboFilters -to allow filtering of events before they are processed by a Logger. -Log4j 2 supports Filters that can be configured to process events before -they are handled by a Logger, as they are processed by a Logger or on an -Appender. -10. Many Logback Appenders do not accept a Layout and will only send -data in a fixed format. Most Log4j 2 Appenders accept a Layout, allowing -the data to be transported in any format desired. -11. Layouts in Log4j 1.x and Logback return a String. This resulted in -the problems discussed at -http://logback.qos.ch/manual/encoders.html[Logback Encoders]. Log4j 2 -takes the simpler approach that xref:manual/layouts.adoc[Layouts] always return -a byte array. This has the advantage that it means they can be used in -virtually any Appender, not just the ones that write to an OutputStream. -12. The xref:manual/appenders.adoc#SyslogAppender[Syslog Appender] supports -both TCP and UDP as well as support for the BSD syslog and the -http://tools.ietf.org/html/rfc5424[RFC 5424] formats. -13. Log4j 2 takes advantage of Java 5 concurrency support and performs -locking at the lowest level possible. Log4j 1.x has known deadlock -issues. Many of these are fixed in Logback but many Logback classes -still require synchronization at a fairly high level. -14. It is an Apache Software Foundation project following the community -and support model used by all ASF projects. If you want to contribute or -gain the right to commit changes just follow the path outlined at -http://jakarta.apache.org/site/contributing.html[Contributing]. +== Welcome to Apache Log4j! + +Welcome to Apache Log4j, one of the world's most widely used logging frameworks. + +Logging is an essential part of the software development process. +It provides a way to track the flow of execution in a program, allowing developers +to understand the application's behavior without needing a debugger. +This is particularly useful when trying to track down a bug or understand +why a particular piece of code is running slow. + +The original concept for Log4j was conceived in early 1996 when the +E.U. SEMPER project decided to develop its own tracing API. +In 2003, the project was donated to the Apache Software Foundation, becoming Apache Log4j. + +Since then, Log4j has seen numerous releases and has become a widely adopted solution. + +== When should you use Log4j? + +Log4j is an excellent choice for any Java application that needs logging capabilities. +It is user-friendly, fast, and flexible. You can use it to log messages at +different levels of severity, from debug to fatal, and you can configure it to +log messages to various destinations, such as files, databases, or the console. + +== When not to use Log4j? + +While Log4j is a highly suitable choice for many applications, +it may be challenging to locate the information you require when +logging a high volume of messages. +Additionally, logging can impact your application's performance. + +Log4j offers solutions to address these concerns. However, if you are in +a unique situation where you are concerned about logging overhead or volume, you may wish +to consider not using logging at all. + +== Benefits of Log4j + +Log4j offers numerous advantages, including: Review Comment: To be coherent with the question-style headers preceding in the page. ```suggestion == What does Log4j offer? Log4j offers numerous features, including: ``` ########## src/site/antora/modules/ROOT/pages/manual/index.adoc: ########## @@ -16,122 +16,57 @@ //// = Manual -== Welcome to Log4j! - -Almost every large application includes its own logging or tracing API. -In conformance with this rule, the E.U. http://www.semper.org[SEMPER] -project decided to write its own tracing API. This was in early 1996. -After countless enhancements, several incarnations and much work that -API has evolved to become log4j, a popular logging package for Java. The -package is distributed under the https://www.apache.org/licenses/LICENSE-2.0[Apache Software -License], a fully-fledged open source license certified by the -http://www.opensource.org[open source] initiative. The latest log4j -version, including full-source code, class files and documentation can -be found at -https://logging.apache.org/log4j/2.x/index.html[*https://logging.apache.org/log4j/2.x/index.html*]. - -Inserting log statements into code is a low-tech method for debugging -it. It may also be the only way because debuggers are not always -available or applicable. This is usually the case for multithreaded -applications and distributed applications at large. - -Experience indicates that logging was an important component of the -development cycle. It offers several advantages. It provides precise -_context_ about a run of the application. Once inserted into the code, -the generation of logging output requires no human intervention. -Moreover, log output can be saved in persistent medium to be studied at -a later time. In addition to its use in the development cycle, a -sufficiently rich logging package can also be viewed as an auditing -tool. - -As Brian W. Kernighan and Rob Pike put it in their truly excellent book -_"The Practice of Programming":_ - -____ -As personal choice, we tend not to use debuggers beyond getting a stack -trace or the value of a variable or two. One reason is that it is easy -to get lost in details of complicated data structures and control flow; -we find stepping through a program less productive than thinking harder -and adding output statements and self-checking code at critical places. -Clicking over statements takes longer than scanning the output of -judiciously-placed displays. It takes less time to decide where to put -print statements than to single-step to the critical section of code, -even assuming we know where that is. More important, debugging -statements stay with the program; debugging sessions are transient. -____ - -Logging does have its drawbacks. It can slow down an application. If too -verbose, it can cause scrolling blindness. To alleviate these concerns, -log4j is designed to be reliable, fast and extensible. Since logging is -rarely the main focus of an application, the log4j API strives to be -simple to understand and to use. - -== Log4j 2 - -Log4j 1 has been widely adopted and used in many applications. -However, through the years development on it has slowed down. It has -become more difficult to maintain due to its need to be compliant with -very old versions of Java and became -https://blogs.apache.org/foundation/entry/apache_logging_services_project_announces[End -of Life] in August 2015. Its alternative, SLF4J/Logback made many needed -improvements to the framework. So why bother with Log4j 2? Here are a -few of the reasons. - -1. Log4j 2 is designed to be usable as an audit logging framework. Both -Log4j 1.x and Logback will lose events while reconfiguring. Log4j 2 will -not. In Logback, exceptions in Appenders are never visible to the -application. In Log4j 2 Appenders can be configured to allow the -exception to percolate to the application. -2. Log4j 2 contains next-generation xref:manual/async.adoc[Asynchronous -Loggers] based on the https://lmax-exchange.github.io/disruptor/[LMAX -Disruptor library]. In multi-threaded scenarios Asynchronous Loggers -have 10 times higher throughput and orders of magnitude lower latency -than Log4j 1.x and Logback. -3. Log4j 2 is xref:manual/garbagefree.adoc[garbage free] for stand-alone -applications, and low garbage for web applications during steady state -logging. This reduces pressure on the garbage collector and can give -better response time performance. -4. Log4j 2 uses a xref:manual/plugins.adoc[Plugin system] that makes it -extremely easy to xref:manual/extending.adoc[extend the framework] by adding -new xref:manual/appenders.adoc[Appenders], xref:manual/filters.adoc[Filters], -xref:manual/layouts.adoc[Layouts], xref:manual/lookups.adoc[Lookups], and Pattern -Converters without requiring any changes to Log4j. -5. Due to the Plugin system configuration is simpler. Entries in the -configuration do not require a class name to be specified. -6. Support for xref:manual/customloglevels.adoc[custom log levels]. Custom log -levels can be defined in code or in configuration. -7. Support for xref:manual/api.adoc#LambdaSupport[lambda expressions]. Client -code running on Java 8 can use lambda expressions to lazily construct a -log message only if the requested log level is enabled. Explicit level -checks are not needed, resulting in cleaner code. -8. Support for xref:manual/messages.adoc[Message objects]. Messages allow -support for interesting and complex constructs to be passed through the -logging system and be efficiently manipulated. Users are free to create -their own `Message` types and write custom xref:manual/layouts.adoc[Layouts], -xref:manual/filters.adoc[Filters] and xref:manual/lookups.adoc[Lookups] to manipulate -them. -9. Log4j 1.x supports Filters on Appenders. Logback added TurboFilters -to allow filtering of events before they are processed by a Logger. -Log4j 2 supports Filters that can be configured to process events before -they are handled by a Logger, as they are processed by a Logger or on an -Appender. -10. Many Logback Appenders do not accept a Layout and will only send -data in a fixed format. Most Log4j 2 Appenders accept a Layout, allowing -the data to be transported in any format desired. -11. Layouts in Log4j 1.x and Logback return a String. This resulted in -the problems discussed at -http://logback.qos.ch/manual/encoders.html[Logback Encoders]. Log4j 2 -takes the simpler approach that xref:manual/layouts.adoc[Layouts] always return -a byte array. This has the advantage that it means they can be used in -virtually any Appender, not just the ones that write to an OutputStream. -12. The xref:manual/appenders.adoc#SyslogAppender[Syslog Appender] supports -both TCP and UDP as well as support for the BSD syslog and the -http://tools.ietf.org/html/rfc5424[RFC 5424] formats. -13. Log4j 2 takes advantage of Java 5 concurrency support and performs -locking at the lowest level possible. Log4j 1.x has known deadlock -issues. Many of these are fixed in Logback but many Logback classes -still require synchronization at a fairly high level. -14. It is an Apache Software Foundation project following the community -and support model used by all ASF projects. If you want to contribute or -gain the right to commit changes just follow the path outlined at -http://jakarta.apache.org/site/contributing.html[Contributing]. +== Welcome to Apache Log4j! + +Welcome to Apache Log4j, one of the world's most widely used logging frameworks. + +Logging is an essential part of the software development process. +It provides a way to track the flow of execution in a program, allowing developers +to understand the application's behavior without needing a debugger. +This is particularly useful when trying to track down a bug or understand +why a particular piece of code is running slow. + +The original concept for Log4j was conceived in early 1996 when the +E.U. SEMPER project decided to develop its own tracing API. +In 2003, the project was donated to the Apache Software Foundation, becoming Apache Log4j. + +Since then, Log4j has seen numerous releases and has become a widely adopted solution. + +== When should you use Log4j? + +Log4j is an excellent choice for any Java application that needs logging capabilities. +It is user-friendly, fast, and flexible. You can use it to log messages at +different levels of severity, from debug to fatal, and you can configure it to +log messages to various destinations, such as files, databases, or the console. + +== When not to use Log4j? + +While Log4j is a highly suitable choice for many applications, +it may be challenging to locate the information you require when +logging a high volume of messages. +Additionally, logging can impact your application's performance. + +Log4j offers solutions to address these concerns. However, if you are in +a unique situation where you are concerned about logging overhead or volume, you may wish +to consider not using logging at all. + +== Benefits of Log4j + +Log4j offers numerous advantages, including: + +1. **Easy to use**: Log4j is easy to use and configure. You can get started + with just a few lines of code. +2. **Speed**: Log4j is fast and has a low overhead. For more information see: xref:manual/async.adoc[Asynchronous Loggers] +3. **Reliable**: Log4j is reliable and has been used in many production applications. +4. **Audit-ready**: Log4j is designed to be a reliable audit logging framework that + does not lose any events, unlike some competing frameworks. +5. **Small footprint**: Log4j has a small impact on the garbage collector. For details, see: xref:manual/garbagefree.adoc[garbage-free]. +6. **Extensible**: Log4j is designed to be easily extended using a xref:manual/plugins.adoc[plugin system], + allowing users to customize it to xref:manual/extending.adoc[fit their specific needs]. +7. **Modern Syntax**: Log4j supports xref:manual/api.adoc#LambdaSupport[lambda expressions] +8. **Integration**: Log4j integrates with numerous other frameworks and libraries. +9. **ASF Standards**: Developed at the Apache Software Foundation, adhering to rigorous standards and best practices. + +== How to learn more? + +To get started, learn more about the xref:manual/api.adoc[Log4j API] and it's xref:manual/architecture.adoc[architecture.] Review Comment: Instead of just linking to API and Architecture pages, I think a question-answer style quick links (just like we have [in the front page](https://logging.apache.org/log4j/2.x/#links)) will be more convenient for users: ```suggestion * xref:manual/installation.adoc[How can I install Log4j?] * xref:manual/configuration.adoc[How can I configure Log4j?] * xref:manual/api.adoc[How can I use Log4j API?] * xref:manual/performance.adoc[How can I tune my Log4j setup for performance?] * xref:manual/migration.adoc[How can I migrate from Log4j 1 to Log4j 2]? * xref:manual/plugins.adoc[What are Log4j plugins] and xref:manual/extending.adoc[how can I use them to extend Log4j?] ``` ########## src/site/antora/modules/ROOT/pages/manual/index.adoc: ########## @@ -16,122 +16,57 @@ //// = Manual -== Welcome to Log4j! - -Almost every large application includes its own logging or tracing API. -In conformance with this rule, the E.U. http://www.semper.org[SEMPER] -project decided to write its own tracing API. This was in early 1996. -After countless enhancements, several incarnations and much work that -API has evolved to become log4j, a popular logging package for Java. The -package is distributed under the https://www.apache.org/licenses/LICENSE-2.0[Apache Software -License], a fully-fledged open source license certified by the -http://www.opensource.org[open source] initiative. The latest log4j -version, including full-source code, class files and documentation can -be found at -https://logging.apache.org/log4j/2.x/index.html[*https://logging.apache.org/log4j/2.x/index.html*]. - -Inserting log statements into code is a low-tech method for debugging -it. It may also be the only way because debuggers are not always -available or applicable. This is usually the case for multithreaded -applications and distributed applications at large. - -Experience indicates that logging was an important component of the -development cycle. It offers several advantages. It provides precise -_context_ about a run of the application. Once inserted into the code, -the generation of logging output requires no human intervention. -Moreover, log output can be saved in persistent medium to be studied at -a later time. In addition to its use in the development cycle, a -sufficiently rich logging package can also be viewed as an auditing -tool. - -As Brian W. Kernighan and Rob Pike put it in their truly excellent book -_"The Practice of Programming":_ - -____ -As personal choice, we tend not to use debuggers beyond getting a stack -trace or the value of a variable or two. One reason is that it is easy -to get lost in details of complicated data structures and control flow; -we find stepping through a program less productive than thinking harder -and adding output statements and self-checking code at critical places. -Clicking over statements takes longer than scanning the output of -judiciously-placed displays. It takes less time to decide where to put -print statements than to single-step to the critical section of code, -even assuming we know where that is. More important, debugging -statements stay with the program; debugging sessions are transient. -____ - -Logging does have its drawbacks. It can slow down an application. If too -verbose, it can cause scrolling blindness. To alleviate these concerns, -log4j is designed to be reliable, fast and extensible. Since logging is -rarely the main focus of an application, the log4j API strives to be -simple to understand and to use. - -== Log4j 2 - -Log4j 1 has been widely adopted and used in many applications. -However, through the years development on it has slowed down. It has -become more difficult to maintain due to its need to be compliant with -very old versions of Java and became -https://blogs.apache.org/foundation/entry/apache_logging_services_project_announces[End -of Life] in August 2015. Its alternative, SLF4J/Logback made many needed -improvements to the framework. So why bother with Log4j 2? Here are a -few of the reasons. - -1. Log4j 2 is designed to be usable as an audit logging framework. Both -Log4j 1.x and Logback will lose events while reconfiguring. Log4j 2 will -not. In Logback, exceptions in Appenders are never visible to the -application. In Log4j 2 Appenders can be configured to allow the -exception to percolate to the application. -2. Log4j 2 contains next-generation xref:manual/async.adoc[Asynchronous -Loggers] based on the https://lmax-exchange.github.io/disruptor/[LMAX -Disruptor library]. In multi-threaded scenarios Asynchronous Loggers -have 10 times higher throughput and orders of magnitude lower latency -than Log4j 1.x and Logback. -3. Log4j 2 is xref:manual/garbagefree.adoc[garbage free] for stand-alone -applications, and low garbage for web applications during steady state -logging. This reduces pressure on the garbage collector and can give -better response time performance. -4. Log4j 2 uses a xref:manual/plugins.adoc[Plugin system] that makes it -extremely easy to xref:manual/extending.adoc[extend the framework] by adding -new xref:manual/appenders.adoc[Appenders], xref:manual/filters.adoc[Filters], -xref:manual/layouts.adoc[Layouts], xref:manual/lookups.adoc[Lookups], and Pattern -Converters without requiring any changes to Log4j. -5. Due to the Plugin system configuration is simpler. Entries in the -configuration do not require a class name to be specified. -6. Support for xref:manual/customloglevels.adoc[custom log levels]. Custom log -levels can be defined in code or in configuration. -7. Support for xref:manual/api.adoc#LambdaSupport[lambda expressions]. Client -code running on Java 8 can use lambda expressions to lazily construct a -log message only if the requested log level is enabled. Explicit level -checks are not needed, resulting in cleaner code. -8. Support for xref:manual/messages.adoc[Message objects]. Messages allow -support for interesting and complex constructs to be passed through the -logging system and be efficiently manipulated. Users are free to create -their own `Message` types and write custom xref:manual/layouts.adoc[Layouts], -xref:manual/filters.adoc[Filters] and xref:manual/lookups.adoc[Lookups] to manipulate -them. -9. Log4j 1.x supports Filters on Appenders. Logback added TurboFilters -to allow filtering of events before they are processed by a Logger. -Log4j 2 supports Filters that can be configured to process events before -they are handled by a Logger, as they are processed by a Logger or on an -Appender. -10. Many Logback Appenders do not accept a Layout and will only send -data in a fixed format. Most Log4j 2 Appenders accept a Layout, allowing -the data to be transported in any format desired. -11. Layouts in Log4j 1.x and Logback return a String. This resulted in -the problems discussed at -http://logback.qos.ch/manual/encoders.html[Logback Encoders]. Log4j 2 -takes the simpler approach that xref:manual/layouts.adoc[Layouts] always return -a byte array. This has the advantage that it means they can be used in -virtually any Appender, not just the ones that write to an OutputStream. -12. The xref:manual/appenders.adoc#SyslogAppender[Syslog Appender] supports -both TCP and UDP as well as support for the BSD syslog and the -http://tools.ietf.org/html/rfc5424[RFC 5424] formats. -13. Log4j 2 takes advantage of Java 5 concurrency support and performs -locking at the lowest level possible. Log4j 1.x has known deadlock -issues. Many of these are fixed in Logback but many Logback classes -still require synchronization at a fairly high level. -14. It is an Apache Software Foundation project following the community -and support model used by all ASF projects. If you want to contribute or -gain the right to commit changes just follow the path outlined at -http://jakarta.apache.org/site/contributing.html[Contributing]. +== Welcome to Apache Log4j! + +Welcome to Apache Log4j, one of the world's most widely used logging frameworks. + +Logging is an essential part of the software development process. +It provides a way to track the flow of execution in a program, allowing developers +to understand the application's behavior without needing a debugger. +This is particularly useful when trying to track down a bug or understand +why a particular piece of code is running slow. + +The original concept for Log4j was conceived in early 1996 when the +E.U. SEMPER project decided to develop its own tracing API. +In 2003, the project was donated to the Apache Software Foundation, becoming Apache Log4j. Review Comment: **Tip:** I think it would be sweet if we can provide some links to these historical facts. ########## src/site/antora/modules/ROOT/pages/manual/index.adoc: ########## Review Comment: While it is not strictly required, I'd appreciate it if you can follow [the one-sentence-per-line convention](https://www.google.com/search?q=one+sentence+per+line). @ppkarwasz, @jvz, and I already adhere to that. ########## src/site/antora/modules/ROOT/pages/manual/index.adoc: ########## @@ -16,122 +16,57 @@ //// = Manual -== Welcome to Log4j! - -Almost every large application includes its own logging or tracing API. -In conformance with this rule, the E.U. http://www.semper.org[SEMPER] -project decided to write its own tracing API. This was in early 1996. -After countless enhancements, several incarnations and much work that -API has evolved to become log4j, a popular logging package for Java. The -package is distributed under the https://www.apache.org/licenses/LICENSE-2.0[Apache Software -License], a fully-fledged open source license certified by the -http://www.opensource.org[open source] initiative. The latest log4j -version, including full-source code, class files and documentation can -be found at -https://logging.apache.org/log4j/2.x/index.html[*https://logging.apache.org/log4j/2.x/index.html*]. - -Inserting log statements into code is a low-tech method for debugging -it. It may also be the only way because debuggers are not always -available or applicable. This is usually the case for multithreaded -applications and distributed applications at large. - -Experience indicates that logging was an important component of the -development cycle. It offers several advantages. It provides precise -_context_ about a run of the application. Once inserted into the code, -the generation of logging output requires no human intervention. -Moreover, log output can be saved in persistent medium to be studied at -a later time. In addition to its use in the development cycle, a -sufficiently rich logging package can also be viewed as an auditing -tool. - -As Brian W. Kernighan and Rob Pike put it in their truly excellent book -_"The Practice of Programming":_ - -____ -As personal choice, we tend not to use debuggers beyond getting a stack -trace or the value of a variable or two. One reason is that it is easy -to get lost in details of complicated data structures and control flow; -we find stepping through a program less productive than thinking harder -and adding output statements and self-checking code at critical places. -Clicking over statements takes longer than scanning the output of -judiciously-placed displays. It takes less time to decide where to put -print statements than to single-step to the critical section of code, -even assuming we know where that is. More important, debugging -statements stay with the program; debugging sessions are transient. -____ - -Logging does have its drawbacks. It can slow down an application. If too -verbose, it can cause scrolling blindness. To alleviate these concerns, -log4j is designed to be reliable, fast and extensible. Since logging is -rarely the main focus of an application, the log4j API strives to be -simple to understand and to use. - -== Log4j 2 - -Log4j 1 has been widely adopted and used in many applications. -However, through the years development on it has slowed down. It has -become more difficult to maintain due to its need to be compliant with -very old versions of Java and became -https://blogs.apache.org/foundation/entry/apache_logging_services_project_announces[End -of Life] in August 2015. Its alternative, SLF4J/Logback made many needed -improvements to the framework. So why bother with Log4j 2? Here are a -few of the reasons. - -1. Log4j 2 is designed to be usable as an audit logging framework. Both -Log4j 1.x and Logback will lose events while reconfiguring. Log4j 2 will -not. In Logback, exceptions in Appenders are never visible to the -application. In Log4j 2 Appenders can be configured to allow the -exception to percolate to the application. -2. Log4j 2 contains next-generation xref:manual/async.adoc[Asynchronous -Loggers] based on the https://lmax-exchange.github.io/disruptor/[LMAX -Disruptor library]. In multi-threaded scenarios Asynchronous Loggers -have 10 times higher throughput and orders of magnitude lower latency -than Log4j 1.x and Logback. -3. Log4j 2 is xref:manual/garbagefree.adoc[garbage free] for stand-alone -applications, and low garbage for web applications during steady state -logging. This reduces pressure on the garbage collector and can give -better response time performance. -4. Log4j 2 uses a xref:manual/plugins.adoc[Plugin system] that makes it -extremely easy to xref:manual/extending.adoc[extend the framework] by adding -new xref:manual/appenders.adoc[Appenders], xref:manual/filters.adoc[Filters], -xref:manual/layouts.adoc[Layouts], xref:manual/lookups.adoc[Lookups], and Pattern -Converters without requiring any changes to Log4j. -5. Due to the Plugin system configuration is simpler. Entries in the -configuration do not require a class name to be specified. -6. Support for xref:manual/customloglevels.adoc[custom log levels]. Custom log -levels can be defined in code or in configuration. -7. Support for xref:manual/api.adoc#LambdaSupport[lambda expressions]. Client -code running on Java 8 can use lambda expressions to lazily construct a -log message only if the requested log level is enabled. Explicit level -checks are not needed, resulting in cleaner code. -8. Support for xref:manual/messages.adoc[Message objects]. Messages allow -support for interesting and complex constructs to be passed through the -logging system and be efficiently manipulated. Users are free to create -their own `Message` types and write custom xref:manual/layouts.adoc[Layouts], -xref:manual/filters.adoc[Filters] and xref:manual/lookups.adoc[Lookups] to manipulate -them. -9. Log4j 1.x supports Filters on Appenders. Logback added TurboFilters -to allow filtering of events before they are processed by a Logger. -Log4j 2 supports Filters that can be configured to process events before -they are handled by a Logger, as they are processed by a Logger or on an -Appender. -10. Many Logback Appenders do not accept a Layout and will only send -data in a fixed format. Most Log4j 2 Appenders accept a Layout, allowing -the data to be transported in any format desired. -11. Layouts in Log4j 1.x and Logback return a String. This resulted in -the problems discussed at -http://logback.qos.ch/manual/encoders.html[Logback Encoders]. Log4j 2 -takes the simpler approach that xref:manual/layouts.adoc[Layouts] always return -a byte array. This has the advantage that it means they can be used in -virtually any Appender, not just the ones that write to an OutputStream. -12. The xref:manual/appenders.adoc#SyslogAppender[Syslog Appender] supports -both TCP and UDP as well as support for the BSD syslog and the -http://tools.ietf.org/html/rfc5424[RFC 5424] formats. -13. Log4j 2 takes advantage of Java 5 concurrency support and performs -locking at the lowest level possible. Log4j 1.x has known deadlock -issues. Many of these are fixed in Logback but many Logback classes -still require synchronization at a fairly high level. -14. It is an Apache Software Foundation project following the community -and support model used by all ASF projects. If you want to contribute or -gain the right to commit changes just follow the path outlined at -http://jakarta.apache.org/site/contributing.html[Contributing]. +== Welcome to Apache Log4j! + +Welcome to Apache Log4j, one of the world's most widely used logging frameworks. + +Logging is an essential part of the software development process. +It provides a way to track the flow of execution in a program, allowing developers +to understand the application's behavior without needing a debugger. +This is particularly useful when trying to track down a bug or understand +why a particular piece of code is running slow. + +The original concept for Log4j was conceived in early 1996 when the +E.U. SEMPER project decided to develop its own tracing API. +In 2003, the project was donated to the Apache Software Foundation, becoming Apache Log4j. + +Since then, Log4j has seen numerous releases and has become a widely adopted solution. + +== When should you use Log4j? + +Log4j is an excellent choice for any Java application that needs logging capabilities. +It is user-friendly, fast, and flexible. You can use it to log messages at +different levels of severity, from debug to fatal, and you can configure it to +log messages to various destinations, such as files, databases, or the console. + +== When not to use Log4j? + +While Log4j is a highly suitable choice for many applications, +it may be challenging to locate the information you require when +logging a high volume of messages. +Additionally, logging can impact your application's performance. + +Log4j offers solutions to address these concerns. However, if you are in +a unique situation where you are concerned about logging overhead or volume, you may wish +to consider not using logging at all. + +== Benefits of Log4j + +Log4j offers numerous advantages, including: + +1. **Easy to use**: Log4j is easy to use and configure. You can get started + with just a few lines of code. +2. **Speed**: Log4j is fast and has a low overhead. For more information see: xref:manual/async.adoc[Asynchronous Loggers] +3. **Reliable**: Log4j is reliable and has been used in many production applications. +4. **Audit-ready**: Log4j is designed to be a reliable audit logging framework that + does not lose any events, unlike some competing frameworks. +5. **Small footprint**: Log4j has a small impact on the garbage collector. For details, see: xref:manual/garbagefree.adoc[garbage-free]. +6. **Extensible**: Log4j is designed to be easily extended using a xref:manual/plugins.adoc[plugin system], + allowing users to customize it to xref:manual/extending.adoc[fit their specific needs]. +7. **Modern Syntax**: Log4j supports xref:manual/api.adoc#LambdaSupport[lambda expressions] +8. **Integration**: Log4j integrates with numerous other frameworks and libraries. +9. **ASF Standards**: Developed at the Apache Software Foundation, adhering to rigorous standards and best practices. Review Comment: I am sort of hesitant about this entire section, since it duplicates [what we already have in the front page](https://logging.apache.org/log4j/2.x/#features). I suggest moving that content to an Antora `partial` and re-using it both here and in the front page. --- I suggest: ```suggestion Easy to use:: Log4j is easy to use and configure. You can xref:5min.adoc[get started] with just a few lines of code. Performance:: When configured correctly, Log4j excels at speed. See the xref:manual/performance.adoc[Performance] page for details. Reliable:: Log4j is reliable and has been used in many production applications. No messages will be lost even during reconfiguration. Extensible:: Log4j is designed to be easily extended using a xref:manual/plugins.adoc[plugin system], allowing users to customize it to xref:manual/extending.adoc[fit their specific needs]. Integration:: Log4j integrates with numerous other frameworks and libraries. ASF Standards:: Developed at the Apache Software Foundation, Log4j adheres to rigorous standards and best practices. ``` Removed _small memory footprint_, since Log4j is the biggest logging API/implementation in the wild. Hence, it is not small by any means, AFAICT. I am also hesitant to advertise garbage-free in the very first page, since 1. It is an advanced feature and we already indirectly share it in the performance page (which we reference above) 1. As @ppkarwasz's recent benchmarks hint, it is not a relevant feature anymore as much as it was in the past thanks to the continuous improvements in the JVM's GC. I removed _modern syntax, lambda expressions_ too, since all popular logging APIs (SLF4J, Tinylog, etc.) support it. I don't think it qualifies as a selling point. -- 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: notifications-unsubscr...@logging.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
