Introduction / FirstSpirit JMX Console / BerkeleyDbBackend

BerkeleyDbBackend

This entry shows information on the connected back end systems. Currently only the Berkley DB back end is supported; therefore, only information about the Berkley Storage Repository of the projects used is displayed in the JMX console. The view, as well as the Repository Manager or Cache Size Manager, is dynamic. This means that the entry is loaded in the JMX console only after the corresponding project has been opened by at least one user. The information is then updated dynamically at runtime. Each project has its own MBean, which is displayed under the "BerkeleyDBBackend" folder.

Attributes

batchCleanerRunning: in addition to the Berkeley DB cleaning tool, an internal cleaner can be used to explicitly call the Berkeley DB cleaning tool.

cachePercent: specifies the cache for the back end as a percentage of the main memory.

cacheSize: specifies the cache size for the back end in bytes.

cleanedLogs: number of log files cleaned up to this point (Berkeley DB database files).

cleanerBacklog: number (queue) of log files not yet cleaned.

cleanerThreads: number of internal Berkeley DB threads responsible for cleaning. The number can change and depends on the value of cleanerBacklogs.

environmentHome: path to the directory where Berkeley DB data are stored (repository).

isReadOnly: information on whether the back end is write-protected (value=true) or not (value=false).

isTransactional: information on whether the back end is transactionally open (value=true) or not (value=false).

lockTimeout: timeout of Berkeley DB internal locks in µs.

runCleaner: information on whether Berkeley DB cleaning is enabled (value=true) or not (value=false).

Operations

The operations displayed here can be executed on cleanLog(), for instance, by clicking on the corresponding button:

java.lang.Integer cleanLog(): executing this method removes obsolete log files (Berkeley DB database files) (return value: number of logs removed by this function).

void evictMemory(): executing this method frees up the Berkeley DB cache.

void sync(): executing this method writes all changed data to the hard disk that have not yet been saved.

In addition to operations, a number of statistics are available that can also be executed by clicking on the relevant field, such as on getLockStats(...) :

void resetStats(): executing this method resets all Berkeley DB statistical information.

java.lang.String getEnvironmentStats(boolean): executing this method displays general statistics about the Berkeley DB.

java.lang.String getLockStats(boolean): executing this method displays the lock statistics.

java.lang.String getDatabaseStats(boolean):  Executing this method displays the statistics of the Berkley DB.

Important It can take a moment for the call if the volume of data is particularly high.

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