com.persistit.mxbeans

Interface BufferPoolMXBean

@MXBean
public interface BufferPoolMXBean

Management structure holding information about the state of a BufferPool, including counters for events such as physical I/O operations, evictions, and hit ratio.

Field Summary

Fields

Modifier and Type	Field and Description
static String	MXBEAN_NAME

Method Summary

Modifier and Type	Method and Description
int	getBufferCount()
int	getBufferSize()
int	getDirtyPageCount() Get the count of dirty pages (pages that contain updates not yet written to disk) in this pool.
long	getEarliestDirtyTimestamp()
long	getEvictCount()
long	getForcedCheckpointWriteCount()
long	getForcedWriteCount()
long	getHitCount() Return the number of lookup operations for pages in this pool for which the page image was already found in this BufferPool.
double	getHitRatio() Get the "hit ratio" - the number of hits divided by the number of overall gets.
long	getMissCount() Return the number of lookup operations for pages that resulted in a physical disk read operation.
long	getNewCount()
int	getReaderClaimedPageCount() Get the count of pages on which running threads have reader (non-exclusive), but not writer (exclusive) claims in this BufferPool.
int	getValidPageCount()
long	getWriteCount()
int	getWriterClaimedPageCount() Get the count of pages on which running threads have writer (exclusive) claims in this BufferPool.

Field Detail

MXBEAN_NAME

static final String MXBEAN_NAME

See Also:

Constant Field Values

Method Detail

getBufferSize

int getBufferSize()

Returns:

The size of Buffers managed by this pool

getBufferCount

int getBufferCount()

Returns:

The count of Buffers managed by this pool.

getMissCount

long getMissCount()

Return the number of lookup operations for pages that resulted in a physical disk read operation. This number, in comparison with the hit counter, indicates how effective the cache is in reducing disk I/O.

Returns:

The miss count

getHitCount

long getHitCount()

Return the number of lookup operations for pages in this pool for which the page image was already found in this BufferPool. This number, in comparison with the get counter, indicates how effective the cache is in reducing disk I/O.

Returns:

The hit count

getNewCount

long getNewCount()

Returns:

Number of pages newly created in this BufferPool.

getEvictCount

long getEvictCount()

Returns:

The number of valid pages evicted from this BufferPool to make room for newly read or created pages.

getWriteCount

long getWriteCount()

Returns:

The total number of pages written to disk from this BufferPool.

getForcedCheckpointWriteCount

long getForcedCheckpointWriteCount()

Returns:

The number of pages written to disk from this BufferPool due to checkpoints.

getForcedWriteCount

long getForcedWriteCount()

Returns:

The number of pages written to disk from this BufferPool due to eviction.

getHitRatio

double getHitRatio()

Get the "hit ratio" - the number of hits divided by the number of overall gets. A value close to 1.0 indicates that most attempts to find data in the BufferPool are successful - i.e., that the cache is effectively reducing the need for disk read operations.

Returns:

The ratio of pages found in this BufferPool to total number of pages accessed

getValidPageCount

int getValidPageCount()

Returns:

The count of valid pages in this BufferPool

getDirtyPageCount

int getDirtyPageCount()

Get the count of dirty pages (pages that contain updates not yet written to disk) in this pool.

Returns:

The count of dirty pages in this pool

getReaderClaimedPageCount

int getReaderClaimedPageCount()

Get the count of pages on which running threads have reader (non-exclusive), but not writer (exclusive) claims in this BufferPool.

Returns:

The count of pages with reader claims

getWriterClaimedPageCount

int getWriterClaimedPageCount()

Get the count of pages on which running threads have writer (exclusive) claims in this BufferPool.

Returns:

The count of pages with writer claims

getEarliestDirtyTimestamp

long getEarliestDirtyTimestamp()

Returns:

Earliest timestamp of any dirty page in this BufferPool.