GemFire 6.6

com.gemstone.gemfire.cache.control
Interface ResourceManager


public interface ResourceManager

Provides support for managing resources used by the local GemFire Cache.

Re-balancing the GemFire Cache resources can be accomplished using a RebalanceOperation:

 ResourceManager resourceManager = cache.getResourceManager();
 RebalanceOperation rebalanceOp = createRebalanceFactory().start();
 
Monitoring of heap utilization is enabled by setting the critical heap percentage using setCriticalHeapPercentage(float).

Since:
6.0

Field Summary
static float DEFAULT_CRITICAL_HEAP_PERCENTAGE
          The default percent of heap memory at which the VM is considered in a critical state.
static float DEFAULT_EVICTION_HEAP_PERCENTAGE
          The default percent of heap memory at which the VM should begin evicting data.
 
Method Summary
 RebalanceFactory createRebalanceFactory()
          Creates a factory for defining and starting RebalanceOperations.
 float getCriticalHeapPercentage()
          Get the percentage of heap at or above which the cache is considered in danger of becoming inoperable.
 float getEvictionHeapPercentage()
          Get the percentage of heap at or above which the eviction should begin on Regions configured for HeapLRU eviction.
 Set<RebalanceOperation> getRebalanceOperations()
          Returns a set of all active RebalanceOperations that were started locally on this member.
 void setCriticalHeapPercentage(float heapPercentage)
          Set the percentage of heap at or above which the cache is considered in danger of becoming inoperable due to garbage collection pauses or out of memory exceptions.
 void setEvictionHeapPercentage(float heapPercentage)
          Set the percentage of heap at or above which the eviction should begin on Regions configured for HeapLRU eviction.
 

Field Detail

DEFAULT_CRITICAL_HEAP_PERCENTAGE

static final float DEFAULT_CRITICAL_HEAP_PERCENTAGE
The default percent of heap memory at which the VM is considered in a critical state. Current value is 0.0.

See Also:
setCriticalHeapPercentage(float), getCriticalHeapPercentage(), Constant Field Values

DEFAULT_EVICTION_HEAP_PERCENTAGE

static final float DEFAULT_EVICTION_HEAP_PERCENTAGE
The default percent of heap memory at which the VM should begin evicting data. Current value is 0.0. Note that if a HeapLRU is created and the eviction heap percentage has not been set then it will default 80.0 unless the critical heap percentage has been set in which case it will default to a value 5.0 less than the critical heap percentage.

See Also:
setEvictionHeapPercentage(float), getEvictionHeapPercentage(), Constant Field Values
Method Detail

createRebalanceFactory

RebalanceFactory createRebalanceFactory()
Creates a factory for defining and starting RebalanceOperations.

Returns:
a factory for defining and starting RebalanceOperations

getRebalanceOperations

Set<RebalanceOperation> getRebalanceOperations()
Returns a set of all active RebalanceOperations that were started locally on this member.

Returns:
a set of all active RebalanceOperations started locally

setCriticalHeapPercentage

void setCriticalHeapPercentage(float heapPercentage)
Set the percentage of heap at or above which the cache is considered in danger of becoming inoperable due to garbage collection pauses or out of memory exceptions.

Changing this value can cause LowMemoryException to be thrown from the following Cache operations:

Only one change to this attribute or the eviction heap percentage will be allowed at any given time and its effect will be fully realized before the next change is allowed. When using this threshold, the VM must be launched with the -Xmx and -Xms switches set to the same values. Many virtual machine implementations have additional VM switches to control the behavior of the garbage collector. We suggest that you investigate tuning the garbage collector when using this type of eviction controller. A collector that frequently collects is needed to keep our heap usage up to date. In particular, on the Sun HotSpot VM, the -XX:+UseConcMarkSweepGC flag needs to be set, and -XX:CMSInitiatingOccupancyFraction=N should be set with N being a percentage that is less than the ResourceManager critical and eviction heap thresholds. The JRockit VM has similar flags, -Xgc:gencon and -XXgcTrigger:N, which are required if using this feature. Please Note: the JRockit gcTrigger flag is based on heap free, not heap in use like the GemFire parameter. This means you need to set gcTrigger to 100-N. for example, if your eviction threshold is 30 percent, you will need to set gcTrigger to 70 percent. On the IBM VM, the flag to get a similar collector is -Xgcpolicy:gencon, but there is no corollary to the gcTrigger/CMSInitiatingOccupancyFraction flags, so when using this feature with an IBM VM, the heap usage statistics might lag the true memory usage of the VM, and thresholds may need to be set sufficiently high that the VM will initiate GC before the thresholds are crossed.

Parameters:
heapPercentage - a percentage of the maximum tenured heap for the VM
Throws:
IllegalStateException - if the heapPercentage value is not >= 0 or <= 100 or when less than the current eviction heap percentage
Since:
6.0
See Also:
getCriticalHeapPercentage(), getEvictionHeapPercentage()

getCriticalHeapPercentage

float getCriticalHeapPercentage()
Get the percentage of heap at or above which the cache is considered in danger of becoming inoperable.

Returns:
either the current or recently used percentage of the maximum tenured heap
Since:
6.0
See Also:
setCriticalHeapPercentage(float)

setEvictionHeapPercentage

void setEvictionHeapPercentage(float heapPercentage)
Set the percentage of heap at or above which the eviction should begin on Regions configured for HeapLRU eviction.

Changing this value may cause eviction to begin immediately.

Only one change to this attribute or critical heap percentage will be allowed at any given time and its effect will be fully realized before the next change is allowed. This feature requires additional VM flags to perform properly. See setCriticalHeapPercentage() for details.

Parameters:
heapPercentage - a percentage of the maximum tenured heap for the VM
Throws:
IllegalStateException - if the heapPercentage value is not >= 0 or <= 100 or when greater than the current critical heap percentage.
Since:
6.0
See Also:
getEvictionHeapPercentage(), getCriticalHeapPercentage()

getEvictionHeapPercentage

float getEvictionHeapPercentage()
Get the percentage of heap at or above which the eviction should begin on Regions configured for HeapLRU eviction.

Returns:
either the current or recently used percentage of the maximum tenured heap
Since:
6.0
See Also:
setEvictionHeapPercentage(float)

GemFire 6.6

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