public class StringDeduplicationRule extends AbstractRule
The rule can only give guidance, it is up to the user to measure changes memory consumption after enabling string deduplication. It can still be that the amount of memory used to hold metadata of the deduplicated strings is more than the saved heap space.
Rule uses the ObjectCount event if available, otherwise the TLAB events. Uncertainties in the calculations comes both from the statistical issues that the AllocationInNewTLAB event provides, and also from the fact that it is hard to know which of the char/byte arrays that actually are the internal string arrays. Looking at the allocation stack trace can help a bit, but allocations can be missed. If using the ObjectCount event, the statistics are better, but it is impossible to know which arrays to count.
Modifier and Type | Field and Description |
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private static java.lang.String |
NEW_LINE |
private static TypedPreference<java.lang.String> |
STRING_ARRAY_ALLOCATION_FRAMES |
private static TypedPreference<IQuantity> |
STRING_ARRAY_ALLOCATION_RATIO_AND_HEAP_USAGE_LIMIT |
private static TypedPreference<IQuantity> |
STRING_ARRAY_LIVESET_RATIO_AND_HEAP_USAGE_LIMIT |
private static IItemFilter |
STRING_FILTER |
evaluationTask
Constructor and Description |
---|
StringDeduplicationRule() |
Modifier and Type | Method and Description |
---|---|
private IItemFilter |
getAllocationFramesFilter(java.lang.String allocationFramesString) |
private Result |
getAllocationRatioResult(IItemCollection items,
java.lang.String stringInternalArrayType,
IItemFilter stringInternalArrayTypeFilter,
IQuantity stringAllocationRatioLimit,
java.lang.String allocationFramesString,
java.lang.String heapInfo,
double heapUsedRatio,
java.lang.String extraGcInfo) |
private Result |
getLivesetRatioResult(IItemCollection items,
java.lang.String stringInternalArrayType,
IItemFilter stringInternalArrayTypeFilter,
IQuantity averageStringSize,
IQuantity stringLivesetRatioAndHeapUsageLimit,
java.lang.String objectCountEventType,
java.lang.String heapInfo,
double heapUsedRatio,
java.lang.String extraGcInfo) |
protected Result |
getResult(IItemCollection items,
IPreferenceValueProvider vp) |
evaluate, getConfigurationAttributes, getId, getName, getTopic
private static final java.lang.String NEW_LINE
private static final IItemFilter STRING_FILTER
private static final TypedPreference<java.lang.String> STRING_ARRAY_ALLOCATION_FRAMES
private static final TypedPreference<IQuantity> STRING_ARRAY_LIVESET_RATIO_AND_HEAP_USAGE_LIMIT
private static final TypedPreference<IQuantity> STRING_ARRAY_ALLOCATION_RATIO_AND_HEAP_USAGE_LIMIT
protected Result getResult(IItemCollection items, IPreferenceValueProvider vp)
getResult
in class AbstractRule
private Result getLivesetRatioResult(IItemCollection items, java.lang.String stringInternalArrayType, IItemFilter stringInternalArrayTypeFilter, IQuantity averageStringSize, IQuantity stringLivesetRatioAndHeapUsageLimit, java.lang.String objectCountEventType, java.lang.String heapInfo, double heapUsedRatio, java.lang.String extraGcInfo)
private Result getAllocationRatioResult(IItemCollection items, java.lang.String stringInternalArrayType, IItemFilter stringInternalArrayTypeFilter, IQuantity stringAllocationRatioLimit, java.lang.String allocationFramesString, java.lang.String heapInfo, double heapUsedRatio, java.lang.String extraGcInfo)
private IItemFilter getAllocationFramesFilter(java.lang.String allocationFramesString)