Enum script::dom::bindings::import::module::jsapi::JSGCParamKey

#[repr(u32)]
pub enum JSGCParamKey {
    JSGC_MAX_BYTES = 0,
    JSGC_MAX_NURSERY_BYTES = 2,
    JSGC_BYTES = 3,
    JSGC_NUMBER = 4,
    JSGC_INCREMENTAL_GC_ENABLED = 5,
    JSGC_PER_ZONE_GC_ENABLED = 6,
    JSGC_UNUSED_CHUNKS = 7,
    JSGC_TOTAL_CHUNKS = 8,
    JSGC_SLICE_TIME_BUDGET_MS = 9,
    JSGC_HIGH_FREQUENCY_TIME_LIMIT = 11,
    JSGC_SMALL_HEAP_SIZE_MAX = 12,
    JSGC_LARGE_HEAP_SIZE_MIN = 13,
    JSGC_HIGH_FREQUENCY_SMALL_HEAP_GROWTH = 14,
    JSGC_HIGH_FREQUENCY_LARGE_HEAP_GROWTH = 15,
    JSGC_LOW_FREQUENCY_HEAP_GROWTH = 16,
    JSGC_BALANCED_HEAP_LIMITS_ENABLED = 17,
    JSGC_HEAP_GROWTH_FACTOR = 18,
    JSGC_ALLOCATION_THRESHOLD = 19,
    JSGC_MIN_EMPTY_CHUNK_COUNT = 21,
    JSGC_MAX_EMPTY_CHUNK_COUNT = 22,
    JSGC_COMPACTING_ENABLED = 23,
    JSGC_PARALLEL_MARKING_ENABLED = 24,
    JSGC_SMALL_HEAP_INCREMENTAL_LIMIT = 25,
    JSGC_LARGE_HEAP_INCREMENTAL_LIMIT = 26,
    JSGC_NURSERY_EAGER_COLLECTION_THRESHOLD_KB = 27,
    JSGC_NURSERY_EAGER_COLLECTION_THRESHOLD_PERCENT = 30,
    JSGC_MIN_NURSERY_BYTES = 31,
    JSGC_MIN_LAST_DITCH_GC_PERIOD = 32,
    JSGC_ZONE_ALLOC_DELAY_KB = 33,
    JSGC_NURSERY_BYTES = 34,
    JSGC_MALLOC_THRESHOLD_BASE = 35,
    JSGC_INCREMENTAL_WEAKMAP_ENABLED = 37,
    JSGC_CHUNK_BYTES = 38,
    JSGC_HELPER_THREAD_RATIO = 39,
    JSGC_MAX_HELPER_THREADS = 40,
    JSGC_HELPER_THREAD_COUNT = 41,
    JSGC_MAJOR_GC_NUMBER = 44,
    JSGC_MINOR_GC_NUMBER = 45,
    JSGC_NURSERY_EAGER_COLLECTION_TIMEOUT_MS = 46,
    JSGC_SYSTEM_PAGE_SIZE_KB = 47,
    JSGC_URGENT_THRESHOLD_MB = 48,
    JSGC_MARKING_THREAD_COUNT = 49,
    JSGC_PARALLEL_MARKING_THRESHOLD_MB = 50,
    JSGC_SEMISPACE_NURSERY_ENABLED = 51,
    JSGC_MAX_MARKING_THREADS = 52,
    JSGC_GENERATE_MISSING_ALLOC_SITES = 53,
    JSGC_SLICE_NUMBER = 54,
}

Variants

JSGC_MAX_BYTES = 0

Maximum nominal heap before last ditch GC.

Soft limit on the number of bytes we are allowed to allocate in the GC heap. Attempts to allocate gcthings over this limit will return null and subsequently invoke the standard OOM machinery, independent of available physical memory.

Pref: javascript.options.mem.max Default: 0xffffffff

JSGC_MAX_NURSERY_BYTES = 2

Maximum size of the generational GC nurseries.

This will be rounded to the nearest gc::ChunkSize.

Pref: javascript.options.mem.nursery.max_kb Default: JS::DefaultNurseryMaxBytes

JSGC_BYTES = 3

Amount of bytes allocated by the GC.

JSGC_NUMBER = 4

Number of times GC has been invoked. Includes both major and minor GC.

JSGC_INCREMENTAL_GC_ENABLED = 5

Whether incremental GC is enabled. If not, GC will always run to completion.

prefs: javascript.options.mem.gc_incremental. Default: false

JSGC_PER_ZONE_GC_ENABLED = 6

Whether per-zone GC is enabled. If not, all zones are collected every time.

prefs: javascript.options.mem.gc_per_zone Default: false

JSGC_UNUSED_CHUNKS = 7

Number of cached empty GC chunks.

JSGC_TOTAL_CHUNKS = 8

Total number of allocated GC chunks.

JSGC_SLICE_TIME_BUDGET_MS = 9

Max milliseconds to spend in an incremental GC slice.

A value of zero means there is no maximum.

Pref: javascript.options.mem.gc_incremental_slice_ms Default: DefaultTimeBudgetMS.

JSGC_HIGH_FREQUENCY_TIME_LIMIT = 11

GCs less than this far apart in milliseconds will be considered ‘high-frequency GCs’.

Pref: javascript.options.mem.gc_high_frequency_time_limit_ms Default: HighFrequencyThreshold

JSGC_SMALL_HEAP_SIZE_MAX = 12

Upper limit for classifying a heap as small (MB).

Dynamic heap growth thresholds are based on whether the heap is small, medium or large. Heaps smaller than this size are classified as small; larger heaps are classified as medium or large.

Pref: javascript.options.mem.gc_small_heap_size_max_mb Default: SmallHeapSizeMaxBytes

JSGC_LARGE_HEAP_SIZE_MIN = 13

Lower limit for classifying a heap as large (MB).

Dynamic heap growth thresholds are based on whether the heap is small, medium or large. Heaps larger than this size are classified as large; smaller heaps are classified as small or medium.

Pref: javascript.options.mem.gc_large_heap_size_min_mb Default: LargeHeapSizeMinBytes

JSGC_HIGH_FREQUENCY_SMALL_HEAP_GROWTH = 14

Heap growth factor for small heaps in the high-frequency GC state.

Pref: javascript.options.mem.gc_high_frequency_small_heap_growth Default: HighFrequencySmallHeapGrowth

JSGC_HIGH_FREQUENCY_LARGE_HEAP_GROWTH = 15

Heap growth factor for large heaps in the high-frequency GC state.

Pref: javascript.options.mem.gc_high_frequency_large_heap_growth Default: HighFrequencyLargeHeapGrowth

JSGC_LOW_FREQUENCY_HEAP_GROWTH = 16

Heap growth factor for low frequency GCs.

This factor is applied regardless of the size of the heap when not in the high-frequency GC state.

Pref: javascript.options.mem.gc_low_frequency_heap_growth Default: LowFrequencyHeapGrowth

JSGC_BALANCED_HEAP_LIMITS_ENABLED = 17

Whether balanced heap limits are enabled.

If this is set to true then heap limits are calculated in a way designed to balance memory usage optimally between many heaps.

Otherwise, heap limits are set based on a linear multiple of the retained size after the last collection.

Pref: javascript.options.mem.gc_balanced_heap_limits Default: BalancedHeapLimitsEnabled

JSGC_HEAP_GROWTH_FACTOR = 18

Heap growth parameter for balanced heap limit calculation.

This parameter trades off GC time for memory usage. Smaller values result in lower memory use and larger values result in less time spent collecting.

Heap limits are set to the heap’s retained size plus some extra space. The extra space is calculated based on several factors but is scaled proportionally to this parameter.

Pref: javascript.options.mem.gc_heap_growth_factor Default: HeapGrowthFactor

JSGC_ALLOCATION_THRESHOLD = 19

Lower limit for collecting a zone (MB).

Zones smaller than this size will not normally be collected.

Pref: javascript.options.mem.gc_allocation_threshold_mb Default GCZoneAllocThresholdBase

JSGC_MIN_EMPTY_CHUNK_COUNT = 21

We try to keep at least this many unused chunks in the free chunk pool at all times, even after a shrinking GC.

Pref: javascript.options.mem.gc_min_empty_chunk_count Default: MinEmptyChunkCount

JSGC_MAX_EMPTY_CHUNK_COUNT = 22

We never keep more than this many unused chunks in the free chunk pool.

Pref: javascript.options.mem.gc_max_empty_chunk_count Default: MaxEmptyChunkCount

JSGC_COMPACTING_ENABLED = 23

Whether compacting GC is enabled.

Pref: javascript.options.mem.gc_compacting Default: CompactingEnabled

JSGC_PARALLEL_MARKING_ENABLED = 24

Whether parallel marking is enabled.

Pref: javascript.options.mem.gc_parallel_marking Default: ParallelMarkingEnabled

JSGC_SMALL_HEAP_INCREMENTAL_LIMIT = 25

Limit of how far over the incremental trigger threshold we allow the heap to grow before finishing a collection non-incrementally, for small heaps.

We trigger an incremental GC when a trigger threshold is reached but the collection may not be fast enough to keep up with the mutator. At some point we finish the collection non-incrementally.

Default: SmallHeapIncrementalLimit Pref: javascript.options.mem.gc_small_heap_incremental_limit

JSGC_LARGE_HEAP_INCREMENTAL_LIMIT = 26

Limit of how far over the incremental trigger threshold we allow the heap to grow before finishing a collection non-incrementally, for large heaps.

Default: LargeHeapIncrementalLimit Pref: javascript.options.mem.gc_large_heap_incremental_limit

JSGC_NURSERY_EAGER_COLLECTION_THRESHOLD_KB = 27

Free space bytes threshold for eager nursery collection.

Default: NurseryChunkUsableSize / 4 Pref: javascript.options.mem.nursery_eager_collection_threshold_kb

JSGC_NURSERY_EAGER_COLLECTION_THRESHOLD_PERCENT = 30

Free space fraction threshold for eager nursery collection. This is a percentage (from 0 to 99).

Default: 25 Pref: javascript.options.mem.nursery_eager_collection_threshold_percent

JSGC_MIN_NURSERY_BYTES = 31

Minimum size of the generational GC nurseries.

This value will be rounded to the nearest Nursery::SubChunkStep if below gc::ChunkSize, otherwise it’ll be rounded to the nearest gc::ChunkSize.

Default: Nursery::SubChunkLimit Pref: javascript.options.mem.nursery.min_kb

JSGC_MIN_LAST_DITCH_GC_PERIOD = 32

The minimum time to allow between triggering last ditch GCs in seconds.

Default: 60 seconds Pref: None

JSGC_ZONE_ALLOC_DELAY_KB = 33

The delay (in heapsize kilobytes) between slices of an incremental GC.

Default: ZoneAllocDelayBytes

JSGC_NURSERY_BYTES = 34

The delay (in heapsize kilobytes) between slices of an incremental GC.

Default: ZoneAllocDelayBytes

JSGC_MALLOC_THRESHOLD_BASE = 35

Retained size base value for calculating malloc heap threshold.

Default: MallocThresholdBase

JSGC_INCREMENTAL_WEAKMAP_ENABLED = 37

Whether incremental weakmap marking is enabled.

Pref: javascript.options.mem.incremental_weakmap Default: IncrementalWeakMarkEnabled

JSGC_CHUNK_BYTES = 38

The chunk size in bytes for this system.

This parameter is read-only.

JSGC_HELPER_THREAD_RATIO = 39

The number of background threads to use for parallel GC work for each CPU core, expressed as an integer percentage.

Pref: javascript.options.mem.gc_helper_thread_ratio

JSGC_MAX_HELPER_THREADS = 40

The maximum number of background threads to use for parallel GC work.

Pref: javascript.options.mem.gc_max_helper_threads

JSGC_HELPER_THREAD_COUNT = 41

The number of background threads to use for parallel GC work.

This parameter is read-only and is set based on the JSGC_HELPER_THREAD_RATIO and JSGC_MAX_HELPER_THREADS parameters.

JSGC_MAJOR_GC_NUMBER = 44

A number that is incremented on every major GC slice.

JSGC_MINOR_GC_NUMBER = 45

A number that is incremented on every minor GC.

JSGC_NURSERY_EAGER_COLLECTION_TIMEOUT_MS = 46

JS::MaybeRunNurseryCollection will collect the nursery if it hasn’t been collected in this many milliseconds.

Default: 5000 Pref: javascript.options.mem.nursery_eager_collection_timeout_ms

JSGC_SYSTEM_PAGE_SIZE_KB = 47

The system page size in KB.

This parameter is read-only.

JSGC_URGENT_THRESHOLD_MB = 48

In an incremental GC, this determines the point at which to start increasing the slice budget and frequency of allocation triggered slices to try to avoid reaching the incremental limit and finishing the collection synchronously.

The threshold is calculated by subtracting this value from the heap’s incremental limit.

JSGC_MARKING_THREAD_COUNT = 49

Get the number of threads used for parallel marking.

Pref: None.

JSGC_PARALLEL_MARKING_THRESHOLD_MB = 50

The heap size above which to use parallel marking.

Pref: javascript.options.mem.gc_parallel_marking_threshold_mb Default: ParallelMarkingThresholdMB

JSGC_SEMISPACE_NURSERY_ENABLED = 51

Whether the semispace nursery is enabled.

Pref: javascript.options.mem.gc_experimental_semispace_nursery Default: SemispaceNurseryEnabled

JSGC_MAX_MARKING_THREADS = 52

Set the maximum number of threads to use for parallel marking, if enabled.

The actual number used is calculated based on the number of available helper threads and can be found by getting the JSGC_MARKING_THREAD_COUNT parameter.

Pref: javascript.options.mem.gc_max_parallel_marking_threads Default: 2.

JSGC_GENERATE_MISSING_ALLOC_SITES = 53

Whether to automatically generate missing allocation sites so data about them can be gathered.

Pref: None, this is an internal engine feature. Default: false.

JSGC_SLICE_NUMBER = 54

A number that is incremented every GC slice.

Trait Implementations

impl Clone for JSGCParamKey

fn clone(&self) -> JSGCParamKey

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for JSGCParamKey

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Hash for JSGCParamKey

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for JSGCParamKey

fn eq(&self, other: &JSGCParamKey) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for JSGCParamKey

impl Eq for JSGCParamKey

impl StructuralPartialEq for JSGCParamKey