Memory Usage

This feature is available only in the Enterprise version of SnappyData.

SnappyData provides statistics for system memory, JVM heap, garbage collection, and table sizes.

You can use these statistics to analyze your application's memory usage. An example follows the table.

Type CachePerfStats
Name RegionStats-<table> and RegsionStats-partition-<table>
Statistic entries
Description Number of rows in the replicated or partitioned table.
Type PartitionedRegionStats
Name PartitionedRegion/<schema>/<table>Statistics
Statistic dataStoreEntryCount and dataStoreBytesInUse
Description Number of rows/bytes in a partitioned table, including redundant copies.
Type VMMemoryUsageStats
Name vmHeapMemoryStats
Statistic usedMemory and maxMemory
Description Used heap and maximum heap, in bytes.
Type VMMemoryUsageStats
Name OffHeapMemoryStats
Statistic usedMemory, maxMemory, freeMemory
Description Used off-heap memory, maximum (amount allocated) off-heap memory, and free off-heap memory in bytes.
Type VMMemoryPoolStats
Name ParSurvivorSpace, ParEdenSpace, CMSOldGen
Statistic currentUsedMemory
Description Estimated used memory, in bytes, for each heap memory pool.
Type VMGCStats
Name ParNew, ConcurrentMarkSweep
Statistic collectionTime
Description Approximate elapsed time that this garbage collector spent doing collections.
Type LinuxSystemStats
Name <hostname>
Statistic pagesSwappedIn, pagesSwappedOut
Description Number of pages that have been brought into memory from disk or flushed out of memory to disk by the operating system. These paging operations seriously degrade performance.

Example: Heap Usage

This VSD chart shows the heap usage in a fabric server plotted against the entry counts in each of the replicated and partitioned tables used in an application. This suggests that heap is growing over time due to an increase in the number of rows in the ORDER_LINE table. Several associated tables are growing in size as well.

This growth can be verified by looking at the bytes used by each of the partitioned tables. The ORDER_LINE table is responsible for most of the heap growth.