Printing JVM Information

3 Printing JVM Information

Enterprise Performance Pack uses Unified JVM Logging, which replaces JDK 8 options that print details about the JVM with -Xlog options.

See JEP 158: Unified JVM Logging for more information.

The following lists JDK 8 options that are automatically mapped to their equivalent -Xlog configuration on Enterprise Performance Pack:

Table 3-1 JDK 8 Options Mapped to Equivalent -Xlog Configuration

JDK 8 Option	`-Xlog` Configuration
`-XX:+PrintGC`	`-Xlog:gc`
`-XX:+PrintGCDetails`	`-Xlog:gc*`
`-XX:+PrintHeapAtGC`	`-Xlog:gc+heap=debug`
`-Xloggc:<filename>`	`-Xlog:gc:<filename>`

The following table lists JDK 8 options and the -Xlog configurations that replace them on Enterprise Performance Pack:

Table 3-2 JDK 8 Options Replaced by Equivalent -Xlog Configuration

JDK 8 Option	`-Xlog` Configuration
`G1PrintHeapRegions`	`-Xlog:gc+region=trace`
`G1PrintRegionLivenessInfo`	`-Xlog:gc+liveness=trace`
`G1SummarizeConcMark`	`-Xlog:gc+marking=trace`
`G1SummarizeRSetStats`	`-Xlog:gc+remset+exit=trace`
`GCLogFileSize`, `NumberOfGCLogFiles`, `UseGCLogFileRotation`	`-Xlog:gc*:file=<filename>::filecount=<count>,filesize=<filesize in kb>`
`PrintAdaptiveSizePolicy`	`-Xlog:gc+ergo*=trace`
`PrintClassHistogramAfterFullGC`	`-Xlog:gc+classhisto=trace`
`PrintClassHistogramBeforeFullGC`	`-Xlog:gc+classhisto=trace`
`PrintGCApplicationConcurrentTime`	`-Xlog:safepoint`
`PrintGCApplicationStoppedTime`	`-Xlog:safepoint`
`PrintGCCause`	Always printed
`PrintGCDateStamps`	`-Xlog:gc*:file=<filename>:time,uptime`
`PrintGCID`	Always printed
`PrintGCTaskTimeStamps`	`-Xlog:gc+task+time=debug`
`PrintGCTimeStamps`	The `uptime` decorator is enabled by default. Alternatively, you can enable it explicitly: `-Xlog:gc*:file=<filename>:time,uptime`
`PrintHeapAtGCExtended`	`-Xlog:gc+heap=trace`
`PrintJNIGCStalls`	`-Xlog:gc+jni=debug`
`PrintOldPLAB`	`-Xlog:gc+plab=trace`
`PrintParallelOldGCPhaseTimes`	`-Xlog:gc+phases=trace`
`PrintPLAB`	`-Xlog:gc+plab=trace`
`PrintPromotionFailure`	`-Xlog:gc+promotion=debug`
`PrintReferenceGC`	`-Xlog:gc+ref=debug`
`PrintStringDeduplicationStatistics`	`-Xlog:gc+stringdedup`
`PrintTenuringDistribution`	`-Xlog:gc+age=trace`
`PrintTLAB`	`-Xlog:gc+tlab=trace`
`TraceAdaptiveGCBoundary`	No equivalent exists. The functionality of the related option `UseAdaptiveGCBoundary` has been removed.
`TraceDynamicGCThreads`	`-Xlog:gc+task=trace`
`TraceMetadataHumongousAllocation`	No equivalent exists, but this configuration prints detailed metaspace information: `-Xlog:gc+metaspace=trace`
`G1TraceConcRefinement`	`-Xlog:gc+refine=debug`
`G1TraceEagerReclaimHumongousObjects` (experimental)	`-Xlog:gc+humongous=debug`
`G1TraceStringSymbolTableScrubbing`	No equivalent exists, but this configuration prints detailed string and symbol table information: `-Xlog:symboltable=trace,stringtable=trace`

Note:

Other flags that print information not related to the garbage collector have been mapped to or replaced by an equivalent -Xlog configuration. See Enable Logging with the JVM Unified Logging Framework in the JDK 17 documentation for the java tool for more information.