Java OpenJDK 17

This page describes the Optimization Pack for Java OpenJDK 17 JVM.

Metrics

Memory

MetricUnitDescription

mem_used

bytes

The total amount of memory used

jvm_heap_size

bytes

The size of the JVM heap memory

jvm_heap_used

bytes

The amount of heap memory used

jvm_heap_util

percent

The utilization % of heap memory

jvm_off_heap_used

bytes

The amount of non-heap memory used

jvm_heap_old_gen_used

bytes

The amount of heap memory used (old generation)

jvm_heap_young_gen_used

bytes

The amount of heap memory used (young generation)

jvm_heap_old_gen_size

bytes

The size of the JVM heap memory (old generation)

jvm_heap_young_gen_size

bytes

The size of the JVM heap memory (young generation)

jvm_memory_used

bytes

The total amount of memory used across all the JVM memory pools

jvm_heap_committed

bytes

The size of the JVM committed memory

jvm_memory_buffer_pool_used

bytes

The total amount bytes used by buffers within the JVM buffer memory pool

CPU

MetricUnitDescription

cpu_util

percent

The average CPU utilization % across all the CPUs (i.e., how much time on average the CPUs are busy doing work)

cpu_used

CPUs

The total amount of CPUs used

Garbage Collection

MetricUnitDescription

jvm_gc_time

percent

The % of wall clock time the JVM spent doing stop the world garbage collection activities

jvm_gc_count

collections/s

The total number of stop the world JVM garbage collections that have occurred per second

jvm_gc_duration

seconds

The average duration of a stop the world JVM garbage collection

Other metrics

MetricUnitDescription

jvm_threads_current

threads

The total number of active threads within the JVM

jvm_threads_deadlocked

threads

The total number of deadlocked threads within the JVM

jvm_compilation_time

milliseconds

The total time spent by the JVM JIT compiler compiling bytecode

Parameters

Memory

NameTypeUnitDefaultDomainRestartDescription

jvm_minHeapSize

integer

megabytes

You should select your own default value.

You should select your own domain.

yes

The minimum heap size.

jvm_maxHeapSize

integer

megabytes

You should select your own default value.

You should select your own domain.

yes

The maximum heap size.

jvm_maxRAM

integer

megabytes

You should select your own default value.

You should select your own domain.

yes

The maximum amount of memory used by the JVM.

jvm_initialRAMPercentage

real

percent

2

1100

yes

The percentage of memory used for initial heap size.

jvm_maxRAMPercentage

integer

percent

25

1100

yes

The percentage of memory used for maximum heap size, on systems with large physical memory size (more than 512MB).

jvm_minRAMPercentage

integer

percent

25

1100

yes

The percentage of memory used for maximum heap size, on systems with small physical memory size (up to 256MB)

jvm_alwaysPreTouch

categorical

-AlwaysPreTouch

+AlwaysPreTouch, -AlwaysPreTouch

yes

Pretouch pages during initialization.

jvm_metaspaceSize

integer

megabytes

20

You should select your own domain within 1 and 1024

yes

The initial size of the allocated class metadata space.

jvm_maxMetaspaceSize

integer

megabytes

20

You should select your own domain within 1 and 1024

yes

The maximum size of the allocated class metadata space.

jvm_useTransparentHugePages

categorical

-UseTransparentHugePages

+UseTransparentHugePages, -UseTransparentHugePages

yes

Enables the use of large pages that can dynamically grow or shrink.

jvm_allocatePrefetchInstr

integer

0

03

yes

Prefetch ahead of the allocation pointer.

jvm_allocatePrefetchDistance

integer

bytes

0

0512

yes

Distance to prefetch ahead of allocation pointer. -1 use system-specific value (automatically determined).

jvm_allocatePrefetchLines

integer

lines

3

064

yes

The number of lines to prefetch ahead of array allocation pointer.

jvm_allocatePrefetchStyle

integer

1

03

yes

Selects the prefetch instruction to generate.

jvm_useLargePages

categorical

+UseLargePages

+UseLargePages, -UseLargePages

yes

Enable the use of large page memory.

jvm_aggressiveHeap

categorical

-AggressiveHeap

-AggressiveHeap, +AggressiveHeap

yes

Optimize heap options for long-running memory intensive apps.

Garbage Collection

NameTypeUnitDefaultDomainRestartDescription

jvm_newRatio

integer

2

02147483647

yes

The ratio of old/new generation sizes.

jvm_newSize

integer

megabytes

You should select your own default value.

You should select your own domain.

yes

Sets the initial and maximum size of the heap for the young generation (nursery).

jvm_maxNewSize

integer

megabytes

You should select your own default value.

You should select your own domain.

yes

Specifies the upper bound for the young generation size.

jvm_survivorRatio

integer

8

1100

yes

The ratio between the Eden and each Survivor-space within the JVM. For example, a jvm_survivorRatio would mean that the Eden-space is 6 times one Survivor-space.

jvm_useAdaptiveSizePolicy

categorical

+UseAdaptiveSizePolicy

+UseAdaptiveSizePolicy, -UseAdaptiveSizePolicy

yes

Enable adaptive generation sizing. Disable coupled with jvm_targetSurvivorRatio.

jvm_adaptiveSizePolicyWeight

integer

10

0 → 100

yes

The weighting given to the current Garbage Collection time versus previous GC times when checking the timing goal.

jvm_targetSurvivorRatio

integer

50

1100

yes

The desired percentage of Survivor-space used after young garbage collection.

jvm_minHeapFreeRatio

integer

40

199

yes

The minimum percentage of heap free after garbage collection to avoid shrinking.

jvm_maxHeapFreeRatio

integer

70

0100

yes

The maximum percentage of heap free after garbage collection to avoid shrinking.

jvm_maxTenuringThreshold

integer

15

015

yes

The maximum value for the tenuring threshold.

jvm_gcType

categorical

G1

Serial, Parallel, G1, Z , Shenandoah

yes

Type of the garbage collection algorithm.

jvm_concurrentGCThreads

integer

threads

You should select your own default value.

You should select your own domain.

yes

The number of threads concurrent garbage collection will use.

jvm_parallelGCThreads

integer

threads

You should select your own default value.

You should select your own domain.

yes

The number of threads garbage collection will use for parallel phases.

jvm_maxGCPauseMillis

integer

milliseconds

200

11000

yes

Adaptive size policy maximum GC pause time goal in millisecond.

jvm_resizePLAB

categorical

+ResizePLAB

+ResizePLAB, -ResizePLAB

yes

Enables the dynamic resizing of promotion LABs.

jvm_GCTimeRatio

integer

99

0100

yes

The target fraction of time that can be spent in garbage collection before increasing the heap, computet as 1 / (1 + GCTimeRatio).

jvm_initiatingHeapOccupancyPercent

integer

45

0100

yes

Sets the percentage of the heap occupancy at which to start a concurrent GC cycle.

jvm_youngGenerationSizeIncrement

integer

20

0100

yes

The increment size for Young Generation adaptive resizing.

jvm_tenuredGenerationSizeIncrement

integer

20

0100

yes

The increment size for Old/Tenured Generation adaptive resizing.

jvm_adaptiveSizeDecrementScaleFactor

integer

4

11024

yes

Specifies the scale factor for goal-driven generation resizing.

jvm_G1HeapRegionSize

integer

megabytes

8

132

yes

Sets the size of the regions for G1.

jvm_G1ReservePercent

integer

10

050

yes

Sets the percentage of the heap that is reserved as a false ceiling to reduce the possibility of promotion failure for the G1 collector.

jvm_G1NewSizePercent

integer

5

0100

yes

Sets the percentage of the heap to use as the minimum for the young generation size.

jvm_G1MaxNewSizePercent

integer

60

0100

yes

Sets the percentage of the heap size to use as the maximum for young generation size.

jvm_G1MixedGCLiveThresholdPercent

integer

85

0100

yes

Sets the occupancy threshold for an old region to be included in a mixed garbage collection cycle.

jvm_G1HeapWastePercent

integer

5

0100

yes

The maximum percentage of the reclaimable heap before starting mixed GC.

jvm_G1MixedGCCountTarget

integer

collections

8

0100

yes

Sets the target number of mixed garbage collections after a marking cycle to collect old regions with at most G1MixedGCLIveThresholdPercent live data. The default is 8 mixed garbage collections.

jvm_G1OldCSetRegionThresholdPercent

integer

10

0100

yes

The upper limit on the number of old regions to be collected during mixed GC.

jvm_G1AdaptiveIHOPNumInitialSamples

integer

3

12097152

yes

The number of completed time periods from initial mark to first mixed GC required to use the input values for prediction of the optimal occupancy to start marking.

jvm_G1UseAdaptiveIHOP

categorical

+G1UseAdaptiveIHOP

+G1UseAdaptiveIHOP, -G1UseAdaptiveIHOP

yes

Adaptively adjust the initiating heap occupancy from the initial value of InitiatingHeapOccupancyPercent.

jvm_G1PeriodicGCInterval

integer

milliseconds

0

03600000

yes

The number of milliseconds after a previous GC to wait before triggering a periodic gc. A value of zero disables periodically enforced gc cycles.

jvm_ZProactive

categorical

+ZProactive

+ZProactive, -ZProactive

yes

Enable proactive GC cycles.

jvm_ZUncommit

categorical

+ZUncommit

+ZUncommit, -ZUncommit

yes

Enable uncommit (free) of unused heap memory back to the OS.

jvm_ZAllocationSpikeTolerance

integer

2

110

yes

The allocation spike tolerance factor for ZGC.

jvm_ZFragmentationLimit

integer

25

1090

yes

The maximum allowed heap fragmentation for ZGC.

jvm_ZCollectionInterval

integer

seconds

0

03600

yes

Force GC at a fixed time interval (in seconds) for ZGC.

jvm_ZMarkStackSpaceLimit

integer

bytes

8589934592

335544321099511627776

yes

The maximum number of bytes allocated for mark stacks for ZGC.

Compilation

NameTypeUnitDefaultDomainRestartDescription

jvm_reservedCodeCacheSize

integer

megabytes

240

322048

yes

The maximum size of the compiled code cache pool.

jvm_tieredCompilation

categorical

+TieredCompilation

+TieredCompilation, -TieredCompilation

yes

The type of the garbage collection algorithm.

jvm_tieredCompilationStopAtLevel

integer

4

04

yes

Overrides the number of detected CPUs that the VM will use to calculate the size of thread pools.

jvm_compilationThreads

integer

threads

You should select your own default value.

You should select your own domain.

yes

The number of compilation threads.

jvm_backgroundCompilation

categorical

+BackgroundCompilation

+BackgroundCompilation, -BackgroundCompilation

yes

Allow async interpreted execution of a method while it is being compiled.

jvm_inline

categorical

+Inline

+Inline, -Inline

yes

Enable inlining.

jvm_maxInlineSize

integer

bytes

35

12097152

yes

The bytecode size limit (in bytes) of the inlined methods.

jvm_inlineSmallCode

integer

bytes

2000

5005000

yes

The maximum compiled code size limit (in bytes) of the inlined methods.

jvm_maxInlineLevel

integer

15

164

yes

The maximum number of nested calls that are inlined by high tier compiler.

jvm_freqInlineSize

integer

bytes

325

13250

yes

The maximum number of bytecode instructions to inline for a method.

jvm_compilationMode

categorical

default

default, quick-only, high-only, high-only-quick-internal

yes

The JVM compilation mode.

jvm_typeProfileWidth

integer

2

18

yes

The number of receiver types to record in call/cast profile.

Other parameters

NameTypeUnitDefaultDomainRestartDescription

jvm_usePerfData

categorical

+UsePerfData

+UsePerfData, -UsePerfData

yes

Enable monitoring of performance data.

jvm_useNUMA

categorical

-UseNUMA

+UseNUMA, -UseNUMA

yes

Enable NUMA.

jvm_useBiasedLocking

categorical

+UseBiasedLocking

+UseBiasedLocking, -UseBiasedLocking

yes

Manage the use of biased locking.

jvm_activeProcessorCount

integer

CPUs

1

1512

yes

Overrides the number of detected CPUs that the VM will use to calculate the size of thread pools.

jvm_threadStackSize

integer

kilobytes

1024

12816384

yes

The thread Stack Size (in Kbytes).

Domains

The following parameters require their ranges or default values to be updated according to the described rules:

Parameter

Default value

Domain

jvm_minHeapSize

Depends on the instance available memory

jvm_maxHeapSize

Depends on the instance available memory

jvm_newSize

Depends on the configured heap

jvm_maxNewSize

Depends on the configured heap

jvm_concurrentGCThreads

Depends on the available CPU cores

Depends on the available CPU cores

jvm_parallelGCThreads

Depends on the available CPU cores

Depends on the available CPU cores

jvm_compilation_threads

Depends on the available CPU cores

Depends on the available CPU cores

Constraints

The following tables show a list of constraints that may be required in the definition of the study, depending on the tuned parameters:

FormulaNotes

jvm.jvm_minHeapSize <= jvm.jvm_maxHeapSize

jvm.jvm_minHeapFreeRatio <= jvm.jvm_maxHeapFreeRatio

jvm.jvm_maxNewSize < jvm.jvm_maxHeapSize * 0.8

jvm.jvm_concurrentGCThreads <= jvm.jvm_parallelGCThreads

jvm_activeProcessorCount < container.cpu_limits/1000 + 1

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