Java OpenJDK 11

This page describes the Optimization Pack for Java OpenJDK 11 JVM.

Metrics

Memory

MetricUnitDescription

mem_used

bytes

The total amount of memory used

requests_throughput

requests/s

The number of requests performed per second

requests_response_time

milliseconds

The average request response time

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_memory_used

bytes

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

jvm_memory_used_details

bytes

The total amount of memory used broken down by pool (e.g., code-cache, compressed-class-space)

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_time_details

percent

The % of wall clock time the JVM spent doing stop the world garbage collection activities broken down by type of garbage collection algorithm (e.g., ParNew)

jvm_gc_count

collections/s

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

jvm_gc_count_details

collections/s

The total number of stop the world JVM garbage collections that have occurred per second, broken down by type of garbage collection algorithm (e.g., G1, CMS)

jvm_gc_duration

seconds

The average duration of a stop the world JVM garbage collection

jvm_gc_duration_details

seconds

The average duration of a stop the world JVM garbage collection broken down by type of garbage collection algorithm (e.g., G1, CMS)

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

NameTypeUnitDafaultDomainRestartDescription

jvm_minHeapSize

integer

megabytes

You should select your own default value.

You should select your own domain.

yes

The inimum 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

1.563

0.1100

yes

The initial percentage of memory used by the JVM.

jvm_maxRAMPercentage

real

percent

25.0

0.1100.0

yes

The percentage of memory used for maximum heap size. Requires Java 10, Java 8 Update 191 or later.

jvm_alwaysPreTouch

categorical

-AlwaysPreTouch

+AlwaysPreTouch, -AlwaysPreTouch

yes

Pretouch pages during initialization.

jvm_metaspaceSize

integer

megabytes

20

You should select your own domain.

yes

The initial size of the allocated class metadata space.

jvm_maxMetaspaceSize

integer

megabytes

20

You should select your own domain.

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

164

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_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

percent

10

1 → 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

percent

40

199

yes

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

jvm_maxHeapFreeRatio

integer

percent

70

1100

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

Parallel

Serial, Parallel, ConcMarkSweep, G1

yes

Type of the garbage collection algorithm.

jvm_useParallelOldGC

categorical

-UseParallelOldGC

+UseParallelOldGC, -UseParallelOldGC

yes

Enables Parallel Mark and Compact Garbage Collection in Old/Tenured generations.

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

132767

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

percent

20

0100

yes

The increment size for Young Generation adaptive resizing.

jvm_tenuredGenerationSizeIncrement

integer

percent

20

0100

yes

The increment size for Old/Tenured Generation adaptive resizing.

jvm_adaptiveSizeDecrementScaleFactor

integer

percent

4

11024

yes

Specifies the scale factor for goal-driven generation resizing.

jvm_CMSTriggerRatio

integer

80

0100

yes

The percentage of MinHeapFreeRatio allocated before CMS GC starts

jvm_CMSInitiatingOccupancyFraction

integer

-1

-199

yes

Configure oldgen occupancy fraction threshold for CMS GC. Negative values default to CMSTriggerRatio.

jvm_CMSClassUnloadingEnabled

categorical

+CMSClassUnloadingEnabled

+CMSClassUnloadingEnabled, -CMSClassUnloadingEnabled

yes

Enables class unloading when using CMS.

jvm_useCMSInitiatingOccupancyOnly

categorical

-UseCMSInitiatingOccupancyOnly

+UseCMSInitiatingOccupancyOnly, -UseCMSInitiatingOccupancyOnly

yes

Use of the occupancy value as the only criterion for initiating the CMS collector.

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.

Compilation

NameTypeUnitDefaultDomainRestartDescription

jvm_reservedCodeCacheSize

integer

megabytes

240

32048

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

116384

yes

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

Other parameters

NameTypeUnitDefaultDomainRestartDescription

jvm_aggressiveOpts

categorical

-AggressiveOpts

+AggressiveOpts, -AggressiveOpts

yes

Turn on point performance compiler optimizations.

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.

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 + 1

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