Java OpenJDK 8
This page describes the Optimization Pack for Java OpenJDK 8 JVM.
Metrics
Memory
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
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
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
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
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
1.563
0.1 → 100
yes
The initial percentage of memory used by the JVM.
jvm_maxRAMPercentage
real
percent
25.0
0.1 → 100.0
yes
The percentage of memory used for maximum heap size, on systems with large physical memory size (more than 512MB). 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 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
0 → 3
yes
Prefetch ahead of the allocation pointer.
jvm_allocatePrefetchDistance
integer
bytes
0
0 → 512
yes
Distance to prefetch ahead of allocation pointer. -1 use system-specific value (automatically determined).
jvm_allocatePrefetchLines
integer
lines
3
1 → 64
yes
The number of lines to prefetch ahead of array allocation pointer.
jvm_allocatePrefetchStyle
integer
1
0 → 3
yes
Selects the prefetch instruction to generate.
jvm_useLargePages
categorical
+UseLargePages
+UseLargePages, -UseLargePages
yes
Enable the use of large page memory.
Garbage Collection
jvm_newRatio
integer
2
0 → 2147483647
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
1 → 100
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
1 → 100
yes
The desired percentage of Survivor-space used after young garbage collection.
jvm_minHeapFreeRatio
integer
40
1 → 99
yes
The minimum percentage of heap free after garbage collection to avoid shrinking.
jvm_maxHeapFreeRatio
integer
70
0 → 100
yes
The maximum percentage of heap free after garbage collection to avoid shrinking.
jvm_maxTenuringThreshold
integer
15
0 → 15
yes
The maximum value for the tenuring threshold.
jvm_gcType
categorical
Parallel
Serial, Parallel, ConcMarkSweep, G1, ParNew
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
1 → 1000
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
0 → 100
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
0 → 100
yes
Sets the percentage of the heap occupancy at which to start a concurrent GC cycle.
jvm_youngGenerationSizeIncrement
integer
20
0 → 100
yes
The increment size for Young Generation adaptive resizing.
jvm_tenuredGenerationSizeIncrement
integer
20
0 → 100
yes
The increment size for Old/Tenured Generation adaptive resizing.
jvm_adaptiveSizeDecrementScaleFactor
integer
4
1 → 1024
yes
Specifies the scale factor for goal-driven generation resizing.
jvm_CMSTriggerRatio
integer
80
0 → 100
yes
The percentage of MinHeapFreeRatio allocated before CMS GC starts
jvm_CMSInitiatingOccupancyFraction
integer
-1
-1 → 99
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
1→32
yes
Sets the size of the regions for G1.
jvm_G1ReservePercent
integer
10
0 → 50
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
0 → 100
yes
Sets the percentage of the heap to use as the minimum for the young generation size.
jvm_G1MaxNewSizePercent
integer
60
0 → 100
yes
Sets the percentage of the heap size to use as the maximum for young generation size.
jvm_G1MixedGCLiveThresholdPercent
integer
85
0 → 100
yes
Sets the occupancy threshold for an old region to be included in a mixed garbage collection cycle.
jvm_G1HeapWastePercent
integer
5
0 → 100
yes
The maximum percentage of the reclaimable heap before starting mixed GC.
jvm_G1MixedGCCountTarget
integer
collections
8
0 → 100
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
0 → 100
yes
The upper limit on the number of old regions to be collected during mixed GC.
Compilation
jvm_reservedCodeCacheSize
integer
megabytes
240
3 → 2048
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
0 → 4
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
1 → 2097152
yes
The bytecode size limit (in bytes) of the inlined methods.
jvm_inlineSmallCode
integer
bytes
2000
1 → 16384
yes
The maximum compiled code size limit (in bytes) of the inlined methods.
Other parameters
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
1 → 512
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:
jvm.jvm_minHeapSize <= jvm.jvm_maxHeapSize
jvm.jvm_minHeapFreeRatio <= jvm.jvm_maxHeapFreeRatio
jvm.jvm_maxNewSize < jvm.jvm_maxHeapSize
jvm.jvm_concurrentGCThreads <= jvm.jvm_parallelGCThreads
Last updated