2973 application. |
2973 application. |
2974 By default, this option is disabled and all pages are committed as the |
2974 By default, this option is disabled and all pages are committed as the |
2975 application uses the heap space. |
2975 application uses the heap space. |
2976 .RS |
2976 .RS |
2977 .RE |
2977 .RE |
2978 .TP |
|
2979 .B \f[CB]\-XX:+CMSClassUnloadingEnabled\f[R] |
|
2980 Enables class unloading when using the concurrent mark\-sweep (CMS) |
|
2981 garbage collector. |
|
2982 This option is enabled by default. |
|
2983 To disable class unloading for the CMS garbage collector, specify |
|
2984 \f[CB]\-XX:\-CMSClassUnloadingEnabled\f[R]. |
|
2985 .RS |
|
2986 .RE |
|
2987 .TP |
|
2988 .B \f[CB]\-XX:CMSExpAvgFactor=\f[R]\f[I]percent\f[R] |
|
2989 Sets the percentage of time (0 to 100) used to weight the current sample |
|
2990 when computing exponential averages for the concurrent collection |
|
2991 statistics. |
|
2992 By default, the exponential averages factor is set to 25%. |
|
2993 The following example shows how to set the factor to 15%: |
|
2994 .RS |
|
2995 .RS |
|
2996 .PP |
|
2997 \f[CB]\-XX:CMSExpAvgFactor=15\f[R] |
|
2998 .RE |
|
2999 .RE |
|
3000 .TP |
|
3001 .B \f[CB]\-XX:CMSInitiatingOccupancyFraction=\f[R]\f[I]percent\f[R] |
|
3002 Sets the percentage of the old generation occupancy (0 to 100) at which |
|
3003 to start a CMS collection cycle. |
|
3004 The default value is set to \-1. |
|
3005 Any negative value (including the default) implies that the option |
|
3006 \f[CB]\-XX:CMSTriggerRatio\f[R] is used to define the value of the |
|
3007 initiating occupancy fraction. |
|
3008 .RS |
|
3009 .PP |
|
3010 The following example shows how to set the factor to 20%: |
|
3011 .RS |
|
3012 .PP |
|
3013 \f[CB]\-XX:CMSInitiatingOccupancyFraction=20\f[R] |
|
3014 .RE |
|
3015 .RE |
|
3016 .TP |
|
3017 .B \f[CB]\-XX:CMSIncrementalDutySafetyFactor=\f[R]\f[I]percent\f[R] |
|
3018 Sets the percentage (0 to 100) used to add conservatism when computing |
|
3019 the duty cycle. |
|
3020 The default value is 10. |
|
3021 .RS |
|
3022 .RE |
|
3023 .TP |
|
3024 .B \f[CB]\-XX:+CMSScavengeBeforeRemark\f[R] |
|
3025 Enables scavenging attempts before the CMS remark step. |
|
3026 By default, this option is disabled. |
|
3027 .RS |
|
3028 .RE |
|
3029 .TP |
|
3030 .B \f[CB]\-XX:CMSTriggerRatio=percent\f[R] |
|
3031 Sets the percentage (0 to 100) of the value specified by the option |
|
3032 \f[CB]\-XX:MinHeapFreeRatio\f[R] that\[aq]s allocated before a CMS |
|
3033 collection cycle commences. |
|
3034 The default value is set to 80%. |
|
3035 .RS |
|
3036 .PP |
|
3037 The following example shows how to set the occupancy fraction to 75%: |
|
3038 .RS |
|
3039 .PP |
|
3040 \f[CB]\-XX:CMSTriggerRatio=75\f[R] |
|
3041 .RE |
|
3042 .RE |
2978 .RE |
3043 .TP |
2979 .TP |
3044 .B \f[CB]\-XX:ConcGCThreads=\f[R]\f[I]threads\f[R] |
2980 .B \f[CB]\-XX:ConcGCThreads=\f[R]\f[I]threads\f[R] |
3045 Sets the number of threads used for concurrent GC. |
2981 Sets the number of threads used for concurrent GC. |
3046 Sets \f[I]\f[CI]threads\f[I]\f[R] to approximately 1/4 of the number of |
2982 Sets \f[I]\f[CI]threads\f[I]\f[R] to approximately 1/4 of the number of |
3068 .TP |
3004 .TP |
3069 .B \f[CB]\-XX:+ExplicitGCInvokesConcurrent\f[R] |
3005 .B \f[CB]\-XX:+ExplicitGCInvokesConcurrent\f[R] |
3070 Enables invoking of concurrent GC by using the \f[CB]System.gc()\f[R] |
3006 Enables invoking of concurrent GC by using the \f[CB]System.gc()\f[R] |
3071 request. |
3007 request. |
3072 This option is disabled by default and can be enabled only with the |
3008 This option is disabled by default and can be enabled only with the |
3073 deprecated \f[CB]\-XX:+UseConcMarkSweepGC\f[R] option and the |
|
3074 \f[CB]\-XX:+UseG1GC\f[R] option. |
3009 \f[CB]\-XX:+UseG1GC\f[R] option. |
3075 .RS |
3010 .RS |
3076 .RE |
3011 .RE |
3077 .TP |
3012 .TP |
3078 .B \f[CB]\-XX:G1AdaptiveIHOPNumInitialSamples=\f[R]\f[I]number\f[R] |
3013 .B \f[CB]\-XX:G1AdaptiveIHOPNumInitialSamples=\f[R]\f[I]number\f[R] |
3458 .RE |
3393 .RE |
3459 .TP |
3394 .TP |
3460 .B \f[CB]\-XX:MaxTenuringThreshold=\f[R]\f[I]threshold\f[R] |
3395 .B \f[CB]\-XX:MaxTenuringThreshold=\f[R]\f[I]threshold\f[R] |
3461 Sets the maximum tenuring threshold for use in adaptive GC sizing. |
3396 Sets the maximum tenuring threshold for use in adaptive GC sizing. |
3462 The largest value is 15. |
3397 The largest value is 15. |
3463 The default value is 15 for the parallel (throughput) collector, and 6 |
3398 The default value is 15 for the parallel (throughput) collector. |
3464 for the CMS collector. |
|
3465 .RS |
3399 .RS |
3466 .PP |
3400 .PP |
3467 The following example shows how to set the maximum tenuring threshold to |
3401 The following example shows how to set the maximum tenuring threshold to |
3468 10: |
3402 10: |
3469 .RS |
3403 .RS |
3722 allocation pool explicitly. |
3656 allocation pool explicitly. |
3723 See the \f[CB]\-XX:SurvivorRatio\f[R] option. |
3657 See the \f[CB]\-XX:SurvivorRatio\f[R] option. |
3724 .RS |
3658 .RS |
3725 .RE |
3659 .RE |
3726 .TP |
3660 .TP |
3727 .B \f[CB]\-XX:+UseCMSInitiatingOccupancyOnly\f[R] |
|
3728 Enables the use of the occupancy value as the only criterion for |
|
3729 initiating the CMS collector. |
|
3730 By default, this option is disabled and other criteria may be used. |
|
3731 .RS |
|
3732 .RE |
|
3733 .TP |
|
3734 .B \f[CB]\-XX:+UseG1GC\f[R] |
3661 .B \f[CB]\-XX:+UseG1GC\f[R] |
3735 Enables the use of the garbage\-first (G1) garbage collector. |
3662 Enables the use of the garbage\-first (G1) garbage collector. |
3736 It\[aq]s a server\-style garbage collector, targeted for multiprocessor |
3663 It\[aq]s a server\-style garbage collector, targeted for multiprocessor |
3737 machines with a large amount of RAM. |
3664 machines with a large amount of RAM. |
3738 This option meets GC pause time goals with high probability, while |
3665 This option meets GC pause time goals with high probability, while |
3972 .PP |
3899 .PP |
3973 The replacement Unified Logging syntax is |
3900 The replacement Unified Logging syntax is |
3974 \f[CB]\-Xlog:class+loader+constraints=info\f[R]. |
3901 \f[CB]\-Xlog:class+loader+constraints=info\f[R]. |
3975 See \f[B]Enable Logging with the JVM Unified Logging Framework\f[R]. |
3902 See \f[B]Enable Logging with the JVM Unified Logging Framework\f[R]. |
3976 .RE |
3903 .RE |
3977 .TP |
|
3978 .B \f[CB]\-XX:+UseConcMarkSweepGC\f[R] |
|
3979 Enables the use of the CMS garbage collector for the old generation. |
|
3980 CMS is an alternative to the default garbage collector (G1), which also |
|
3981 focuses on meeting application latency requirements. |
|
3982 By default, this option is disabled and the collector is selected |
|
3983 automatically based on the configuration of the machine and type of the |
|
3984 JVM. |
|
3985 The CMS garbage collector is deprecated. |
|
3986 .RS |
|
3987 .RE |
|
3988 .SH OBSOLETE JAVA OPTIONS |
|
3989 .PP |
|
3990 These \f[CB]java\f[R] options are still accepted but ignored, and a |
|
3991 warning is issued when they\[aq]re used. |
|
3992 .TP |
3904 .TP |
3993 .B \f[CB]\-XX:+UseMembar\f[R] |
3905 .B \f[CB]\-XX:+UseMembar\f[R] |
3994 Enabled issuing membars on thread\-state transitions. |
3906 Enabled issuing membars on thread\-state transitions. |
3995 This option was disabled by default on all platforms except ARM servers, |
3907 This option was disabled by default on all platforms except ARM servers, |
3996 where it was enabled. |
3908 where it was enabled. |