7240-Enable verbose garbage collection by default on IBM Java-Semeru-1

 7240-Enable verbose garbage collection by default on IBM Java-Semeru-1

#7240

modules/ROOT/pages/log-trace-configuration.adoc

@@ -14,16 +14,18 @@
 
 Open Liberty has a unified logging component that handles messages that are written by applications and the runtime, and provides First Failure Data Capture (FFDC) capability. Logging data that is written by applications by using the `System.out`, `System.err`, or `java.util.logging.Logger` streams is combined into the server logs.
 
-A server has the following three primary log files:
+A server has the following four primary log files:
 
 - `console.log` - This file is created by the `server start` command. It contains the redirected standard output and standard error streams from the underlying JVM process. This console output is formatted for human readability and it lacks some information that is useful for automated log analysis. The `console.log` file is reset when the server is restarted.
 - `messages.log` - This file contains all messages that are written or captured by the logging component. All messages that are written to this file contain additional information such as the message timestamp and the ID of the thread that wrote the message. This file is suitable for automated log analysis. This file does not contain messages that are written directly by the JVM process.
 - `trace.log` - This file is created only if you enable trace. It contains all the content of the `messages.log` file plus any enabled trace. This file does not contain messages that are written directly by the JVM process.
+- `verbosegc.XXX.log` - This file contains the verbose garbage collection output from the JVM, generated by running IBM Java and IBM Semeru Runtimes. Up to ten rolling log files are maintained, with each file's log number denoted by `XXX`.
 
 The following sections provide more information about configuring your Open Liberty logs:
 
 * <<#configuaration,Logging configuration>>
 * <<#storage,Log file storage management>>
+* <<#verbosegc,Verbose garbage collection logging>>
 * <<#log_formats,Log formats>>
 * <<#json,JSON logging>>
   ** <<#names,Configurable JSON field names>>
@@ -56,6 +58,12 @@ com.ibm.ws.logging.console.log.level=OFF
 com.ibm.ws.logging.copy.system.streams=false
 ----
 
+[#verbosegc]
+== Verbose garbage collection logging
+If you are using IBM Java, verbose garbage collection logging is enabled by default. This feature generates up to 10 rotating log files within the logs directory. Verbose garbage collection logging is valuable for diagnosing performance problems and `OutOfMemory` errors. Keep the logging feature active in production environments, as it impacts performance by less than 1%.If you set up your own verbose garbage collection configurations, those settings take precedence over the default ones. To turn off verbose GC logging, add `VERBOSEGC=false` to your `server.env` file.
+
+For more information on verbose garbage collection logs, see https://www.ibm.com/docs/en/sdk-java-technology/8?topic=gc-verbose-logs[Verbose garbage collection logs]. 
+
 [#log_formats]
 == Log formats