Interface MemoryPressureController

All Known Implementing Classes:
MemoryPressureController.JvmMemoryPressureController
Functional Interface:
This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
@FunctionalInterface public interface MemoryPressureController
Determines whether caches should proactively shed entries.

  • Field Details

    • MEMORY_PRESSURE_HEAP_THRESHOLD_PERCENT_PROPERTY

      static final String MEMORY_PRESSURE_HEAP_THRESHOLD_PERCENT_PROPERTY
      Post-GC heap usage percentage that triggers JVM-wide memory-aware cache trimming. Defaults to 85. Measuring retained occupancy instead of instantaneous Eden usage prevents a normal allocation burst just before a young collection from evicting hot cache entries.
      See Also:

    • MEMORY_PRESSURE_GC_TIME_THRESHOLD_PERCENT_PROPERTY

      static final String MEMORY_PRESSURE_GC_TIME_THRESHOLD_PERCENT_PROPERTY
      GC-time percentage over the sampling window that triggers JVM-wide memory-aware cache trimming. Defaults to 20. GC pressure is evaluated over a sustained window so a single short collection does not evict hot cache entries while heap usage remains healthy.
      See Also:

    • MEMORY_PRESSURE_GC_CACHE_UTILIZATION_PERCENT_PROPERTY

      static final String MEMORY_PRESSURE_GC_CACHE_UTILIZATION_PERCENT_PROPERTY
      Minimum occupied percentage of a cache's configured weight budget before sustained GC time alone may trigger trimming. Defaults to 50. Actual post-GC heap pressure remains sufficient by itself.
      See Also:

    • MEMORY_PRESSURE_TRIM_RATIO_PERCENT_PROPERTY

      static final String MEMORY_PRESSURE_TRIM_RATIO_PERCENT_PROPERTY
      Percentage of the registered memory-aware cache weight to evict per observed memory-pressure pass. Defaults to 20.
      See Also:

    • MEMORY_PRESSURE_MAX_TRIM_WEIGHT_PROPERTY

      static final String MEMORY_PRESSURE_MAX_TRIM_WEIGHT_PROPERTY
      Maximum cache weight to evict per observed memory-pressure pass. For byte-weighted caches this is bytes; for count-weighted caches this is entries. Defaults to 1 GiB.
      See Also:

    • NONE

      static final MemoryPressureController NONE

  • Method Details

    • shouldEvict

      boolean shouldEvict(long currentWeight, long maxWeight)
      Returns whether memory pressure warrants eviction given the current cache weight and configured maximum weight.

    • trimRatioPercent

      default int trimRatioPercent()
      Returns the percentage of cache weight targeted by a pressure-driven trim.

    • maxTrimWeight

      default long maxTrimWeight()
      Returns the maximum cache weight to remove in one pressure-driven trim.

    • none

      static MemoryPressureController none()
      Returns a controller that never requests memory-pressure eviction.

    • jvm

      static MemoryPressureController jvm()
      Creates a controller using JVM memory pressure and the default property source.

    • jvm

      static MemoryPressureController jvm(PropertySource propertySource)
      Creates a JVM memory-pressure controller configured through the supplied property source.