2222.\" t
2323.\" Automatically generated by Pandoc 2.3.1
2424.\"
25- .TH "JAVA" "1" "2021 " "JDK 18\- ea " "JDK Commands"
25+ .TH "JAVA" "1" "2022 " "JDK 18" "JDK Commands"
2626.hy
2727.SH NAME
2828.PP
@@ -935,11 +935,11 @@ size of the heap for the young generation, you can use
935935.RE
936936.TP
937937.B \f[CB] \- Xms \f[ R ] \f[I] size \f[ R ]
938- Sets the minimum and initial size (in bytes) of the heap.
938+ Sets the minimum and the initial size (in bytes) of the heap.
939939This value must be a multiple of 1024 and greater than 1 MB.
940940Append the letter \f[CB] k \f[ R ] or \f[CB] K \f[ R ] to indicate kilobytes,
941- \f[CB] m \f[ R ] or \f[CB] M \f[ R ] to indicate megabytes, \f[CB] g \f[ R ] or \f[CB] G \f[ R ]
942- to indicate gigabytes.
941+ \f[CB] m \f[ R ] or \f[CB] M \f[ R ] to indicate megabytes, or \f[CB] g \f[ R ] or
942+ \f[CB] G \f[ R ] to indicate gigabytes.
943943The following examples show how to set the size of allocated memory to 6
944944MB using various units:
945945.RS
@@ -952,14 +952,17 @@ MB using various units:
952952\f[ R ]
953953.fi
954954.PP
955- Instead of the \f[CB] \- Xms \f[ R ] option to set both the minimum and initial
956- size of the heap, you can use \f[CB] \- XX:MinHeapSize \f[ R ] to set the
957- minimum size and \f[CB] \- XX:InitialHeapSize \f[ R ] to set the initial size.
958- .PP
959- If you don\[aq ] t set this option, the initial size is set as the sum of
960- the sizes allocated for the old generation and the young generation.
955+ If you do not set this option, then the initial size will be set as the
956+ sum of the sizes allocated for the old generation and the young
957+ generation.
961958The initial size of the heap for the young generation can be set using
962959the \f[CB] \- Xmn \f[ R ] option or the \f[CB] \- XX:NewSize \f[ R ] option.
960+ .PP
961+ Note that the \f[CB] \- XX:InitialHeapSize \f[ R ] option can also be used to
962+ set the initial heap size.
963+ If it appears after \f[CB] \- Xms \f[ R ] on the command line, then the initial
964+ heap size gets set to the value specified with
965+ \f[CB] \- XX:InitialHeapSize \f[ R ] .
963966.RE
964967.TP
965968.B \f[CB] \- Xmx \f[ R ] \f[I] size \f[ R ]
@@ -1366,7 +1369,7 @@ By default this option is disabled.
13661369.RS
13671370.RE
13681371.TP
1369- .B \f[CB] \- XX:FlightRecorderOptions= \f[ R ]\f[I] parameter \f[ R ]\f[CB] = \f[ R ]\f[I] value \f[ R ] (or)\f[CB] \- XX:FlightRecorderOptions: \f[ R ]\f[I] parameter \f[ R ]\f[CB] = \f[ R ]\f[I] value \f[ R ]
1372+ .B \f[CB] \- XX:FlightRecorderOptions= \f[ R ]\f[I] parameter \f[ R ]\f[CB] = \f[ R ]\f[I] value \f[ R ] (or) \f[CB] \- XX:FlightRecorderOptions: \f[ R ]\f[I] parameter \f[ R ]\f[CB] = \f[ R ]\f[I] value \f[ R ]
13701373Sets the parameters that control the behavior of JFR.
13711374.RS
13721375.PP
@@ -1640,7 +1643,7 @@ Specifies the path and name of the class data sharing (CDS) archive file
16401643See \f[B] Application Class Data Sharing \f[ R ] .
16411644.RE
16421645.TP
1643- .B \f[CB] \- XX:SharedArchiveConfigFile \f[ R ]= \f[I] shared_config_file \f[ R ]
1646+ .B \f[CB] \- XX:SharedArchiveConfigFile= \f[ R ]\f[I] shared_config_file \f[ R ]
16441647Specifies additional shared data added to the archive file.
16451648.RS
16461649.RE
@@ -1747,9 +1750,6 @@ written when the recording is stopped, for example:
17471750\f[CB] /home/user/recordings/recording.jfr \f[ R ]
17481751.IP \[bu ] 2
17491752\f[CB] c: \\r ecordings \\r ecording.jfr \f[ R ]
1750- .PP
1751- If \f[CB] %p \f[ R ] and/or \f[CB] %t \f[ R ] is specified in the filename, it expands to the JVM\[aq ] s
1752- PID and the current timestamp, respectively.
17531753.RE
17541754.TP
17551755.B \f[CB] name= \f[ R ]\f[I] identifier \f[ R ]
@@ -1825,10 +1825,10 @@ To list available options, use the \f[CB]JAVA_HOME\f[R]/bin/jfr tool.
18251825.RS
18261826.RE
18271827.TP
1828- .B \f[CB] event \- setting \f[ R ]= \f[I] value \f[ R ]
1828+ .B \f[CB] event \- setting= \f[ R ]\f[I] value \f[ R ]
18291829Specifies the event setting value to modify.
1830- Use the form: #= To add a new event setting, prefix the event name with
1831- \[aq ] +\[aq ] .
1830+ Use the form: \f[CB] < event\- name>#< setting\- name>=<value> \f[ R ] .
1831+ To add a new event setting, prefix the event name with \[aq ] +\[aq ] .
18321832.RS
18331833.RE
18341834.PP
@@ -2591,23 +2591,19 @@ The \f[CB]\-XX:UseRTMLocking\f[R] option must be enabled.
25912591.RE
25922592.TP
25932593.B \f[CB] \- XX:+SegmentedCodeCache \f[ R ]
2594- Enables segmentation of the code cache.
2595- Without the \f[CB] \- XX:+SegmentedCodeCache \f[ R ] , the code cache consists
2596- of one large segment.
2597- With \f[CB] \- XX:+SegmentedCodeCache \f[ R ] , we have separate segments for
2598- nonmethod, profiled method, and nonprofiled method code.
2599- These segments aren\[aq ] t resized at runtime.
2600- The feature is enabled by default if tiered compilation is enabled
2601- (\f[CB] \- XX:+TieredCompilation \f[ R ] ) and
2602- \f[CB] \- XX:ReservedCodeCacheSize \f[ R ] >= 240 MB.
2594+ Enables segmentation of the code cache, without which the code cache
2595+ consists of one large segment.
2596+ With \f[CB] \- XX:+SegmentedCodeCache \f[ R ] , separate segments will be used
2597+ for non\- method, profiled method, and non\- profiled method code.
2598+ The segments are not resized at runtime.
26032599The advantages are better control of the memory footprint, reduced code
2604- fragmentation, and better iTLB/iCache behavior due to improved locality.
2605- iTLB/iCache is a CPU\- specific term meaning Instruction Translation
2606- Lookaside Buffer (ITLB).
2607- ICache is an instruction cache in theCPU.
2608- The implementation of the code cache can be found in the file:
2609- \f[CB] /share/vm/code/codeCache.cpp \f[ R ] .
2600+ fragmentation, and better CPU iTLB (instruction translation lookaside
2601+ buffer) and instruction cache behavior due to improved locality.
26102602.RS
2603+ .PP
2604+ The feature is enabled by default if tiered compilation is enabled
2605+ (\f[CB] \- XX:+TieredCompilation \f[ R ] ) and the reserved code cache size
2606+ (\f[CB] \- XX:ReservedCodeCacheSize \f[ R ] ) is at least 240 MB.
26112607.RE
26122608.TP
26132609.B \f[CB] \- XX:StartAggressiveSweepingAt= \f[ R ]\f[I] percent \f[ R ]
@@ -2639,16 +2635,17 @@ Is set by default to the highest supported version available (x86 only).
26392635Enables hardware\- based AES intrinsics for hardware that supports it.
26402636This option is on by default on hardware that has the necessary
26412637instructions.
2642- The \f[CB] \- XX:+UseAES \f[ R ] is used in conjunction with UseAESIntrinsics.
2638+ The \f[CB] \- XX:+UseAES \f[ R ] is used in conjunction with
2639+ \f[CB] UseAESIntrinsics \f[ R ] .
26432640Flags that control intrinsics now require the option
26442641\f[CB] \- XX:+UnlockDiagnosticVMOptions \f[ R ] .
26452642.RS
26462643.RE
26472644.TP
26482645.B \f[CB] \- XX:+UseAESIntrinsics \f[ R ]
26492646Enables AES intrinsics.
2650- Specifying\f[CB] \- XX:+UseAESIntrinsics \f[ R ] is equivalent to also enabling
2651- \f[CB] \- XX:+UseAES \f[ R ] .
2647+ Specifying \f[CB] \- XX:+UseAESIntrinsics \f[ R ] is equivalent to also
2648+ enabling \f[CB] \- XX:+UseAES \f[ R ] .
26522649To disable hardware\- based AES intrinsics, specify
26532650\f[CB] \- XX: \- UseAES \ \- XX: \- UseAESIntrinsics \f[ R ] .
26542651For example, to enable hardware AES, use the following flags:
@@ -2844,7 +2841,7 @@ The default value is 1,000.
28442841.RS
28452842.RE
28462843.TP
2847- .B \f[CB] \- XX:LoopStripMiningIterShortLoop \f[ R ]= \f[I] number_of_iterations \f[ R ]
2844+ .B \f[CB] \- XX:LoopStripMiningIterShortLoop= \f[ R ]\f[I] number_of_iterations \f[ R ]
28482845Controls loop strip mining optimization.
28492846Loops with the number of iterations less than specified will not have
28502847safepoints in them.
@@ -2971,7 +2968,7 @@ an \f[CB]OutOfMemoryError\f[R] exception is thrown.
29712968.RS
29722969.RE
29732970.TP
2974- .B \f[CB] \- XX:HeapDumpPath=path \f[ R ]
2971+ .B \f[CB] \- XX:HeapDumpPath= \f[ R ] \f[I] path \f[ R ]
29752972Sets the path and file name for writing the heap dump provided by the
29762973heap profiler (HPROF) when the \f[CB] \- XX:+HeapDumpOnOutOfMemoryError \f[ R ]
29772974option is set.
@@ -3165,7 +3162,7 @@ The default value is 3.
31653162.RS
31663163.RE
31673164.TP
3168- .B \f[CB] \- XX:G1HeapRegionSize=size \f[ R ]
3165+ .B \f[CB] \- XX:G1HeapRegionSize= \f[ R ] \f[I] size \f[ R ]
31693166Sets the size of the regions into which the Java heap is subdivided when
31703167using the garbage\- first (G1) collector.
31713168The value is a power of 2 and can range from 1 MB to 32 MB.
@@ -3294,6 +3291,11 @@ If you set this option to 0, then the initial size is set as the sum of
32943291the sizes allocated for the old generation and the young generation.
32953292The size of the heap for the young generation can be set using the
32963293\f[CB] \- XX:NewSize \f[ R ] option.
3294+ Note that the \f[CB] \- Xms \f[ R ] option sets both the minimum and the
3295+ initial heap size of the heap.
3296+ If \f[CB] \- Xms \f[ R ] appears after \f[CB] \- XX:InitialHeapSize \f[ R ] on the
3297+ command line, then the initial heap size gets set to the value specified
3298+ with \f[CB] \- Xms \f[ R ] .
32973299.RE
32983300.TP
32993301.B \f[CB] \- XX:InitialRAMPercentage= \f[ R ]\f[I] percent \f[ R ]
@@ -3895,7 +3897,7 @@ Supports heap sizes from 8MB to 16TB.
38953897.RS
38963898.RE
38973899.TP
3898- .B \f[CB] \- XX:ZAllocationSpikeTolerance \f[ R ]= \f[I] factor \f[ R ]
3900+ .B \f[CB] \- XX:ZAllocationSpikeTolerance= \f[ R ]\f[I] factor \f[ R ]
38993901Sets the allocation spike tolerance for ZGC.
39003902By default, this option is set to 2.0.
39013903This factor describes the level of allocation spikes to expect.
@@ -3904,14 +3906,14 @@ be expected to triple at any time.
39043906.RS
39053907.RE
39063908.TP
3907- .B \f[CB] \- XX:ZCollectionInterval \f[ R ]= \f[I] seconds \f[ R ]
3909+ .B \f[CB] \- XX:ZCollectionInterval= \f[ R ]\f[I] seconds \f[ R ]
39083910Sets the maximum interval (in seconds) between two GC cycles when using
39093911ZGC.
39103912By default, this option is set to 0 (disabled).
39113913.RS
39123914.RE
39133915.TP
3914- .B \f[CB] \- XX:ZFragmentationLimit \f[ R ]= \f[I] percent \f[ R ]
3916+ .B \f[CB] \- XX:ZFragmentationLimit= \f[ R ]\f[I] percent \f[ R ]
39153917Sets the maximum acceptable heap fragmentation (in percent) for ZGC.
39163918By default, this option is set to 25.
39173919Using a lower value will cause the heap to be compacted more
@@ -3939,7 +3941,7 @@ JVM, and make that memory available for other processes to use.
39393941.RS
39403942.RE
39413943.TP
3942- .B \f[CB] \- XX:ZUncommitDelay \f[ R ]= \f[I] seconds \f[ R ]
3944+ .B \f[CB] \- XX:ZUncommitDelay= \f[ R ]\f[I] seconds \f[ R ]
39433945Sets the amount of time (in seconds) that heap memory must have been
39443946unused before being uncommitted.
39453947By default, this option is set to 300 (5 minutes).
@@ -4231,7 +4233,7 @@ In the argument file,
42314233.nf
42324234\f[CB]
42334235\- cp \ "/lib/cool \\
4234- \\a pp/jars???
4236+ \\a pp/jars"
42354237\f[ R ]
42364238.fi
42374239.PP
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