com.aquenos.cassandra.pvarchiver.server.spring

Class ThrottlingProperties

java.lang.Object

com.aquenos.cassandra.pvarchiver.server.spring.ThrottlingProperties

@ConfigurationProperties(prefix="throttling",
                         ignoreUnknownFields=false)
public class ThrottlingProperties
extends Object

Configuration properties that control throttling of operations. Throttling is needed in order to avoid exhausting system resources or overloading the Cassandra database cluster. This object is injected with properties that have the throttling.* prefix.

At the moment, throttling options are provided for two areas of operation:

Concurrently executed Cassandra statements: Processing statements causes load on the database cluster. When processing too many statements in parallel, this can lead to a situation in which statements take so long to be processed that they time out. This can be avoided by limiting the number of statements that are executed concurrently. The limits can be set separately for two areas: statements that read or write samples (such statements are used by the control-system supports) and statements that deal with sample meta-data (such statements are used by the ChannelMetaDataDAO.

Sample decimation: When adding a decimation level to a lot of channels that already have a lot of raw samples, generating the decimated samples can consume a lot of resources because this process involves reading all the source (raw) samples. In particular, due to the fact that samples are read from the database in pages, a lot of memory might be consumed for samples that have been read from the database, but have not been processed yet. This can lead to a situation in which the decimation process consumes all available heap memory and triggers an OutOfMemoryError. By limiting the number of samples that may be kept in memory and delaying the reading of samples for other channels until some of the samples in memory have been processed, the amount of memory used can be limited.

Instances of this class are safe for concurrent read access but are not safe for concurrent write access. Typically, this should not be a problem because an instance of this class is initialized once at application startup and then only used for read access.

Author:

Sebastian Marsching

Constructor Summary

Constructors

Constructor and Description
ThrottlingProperties() Creates a properties object, initializing all properties with their default values.

Method Summary

Modifier and Type	Method and Description
int	getMaxConcurrentChannelMetaDataReadStatements() Returns the maximum number of read statements that may be concurrently executed by the ChannelMetaDataDAO.
int	getMaxConcurrentChannelMetaDataWriteStatements() Returns the maximum number of write statements that may be concurrently executed by the ChannelMetaDataDAO.
int	getMaxConcurrentControlSystemSupportReadStatements() Returns the maximum number of read statements that may be concurrently executed by all ControlSystemSupports.
int	getMaxConcurrentControlSystemSupportWriteStatements() Returns the maximum number of write statements that may be concurrently executed by all ControlSystemSupports.
SampleDecimationThrottlingProperties	getSampleDecimation() Returns the configuration properties that control the sample decimation process.
void	setMaxConcurrentChannelMetaDataReadStatements(int maxConcurrentChannelMetaDataReadStatements) Sets the maximum number of read statements that may be concurrently executed by the ChannelMetaDataDAO.
void	setMaxConcurrentChannelMetaDataWriteStatements(int maxConcurrentChannelMetaDataWriteStatements) Sets the maximum number of write statements that may be concurrently executed by the ChannelMetaDataDAO.
void	setMaxConcurrentControlSystemSupportReadStatements(int maxConcurrentControlSystemSupportReadStatements) Sets the maximum number of read statements that may be concurrently executed by all ControlSystemSupports.
void	setMaxConcurrentControlSystemSupportWriteStatements(int maxConcurrentControlSystemSupportWriteStatements) Sets the maximum number of write statements that may be concurrently executed by all ControlSystemSupports.
void	setSampleDecimation(SampleDecimationThrottlingProperties sampleDecimation) Sets the configuration properties that control the sample decimation process.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ThrottlingProperties

public ThrottlingProperties()

Creates a properties object, initializing all properties with their default values.

Method Detail

getMaxConcurrentChannelMetaDataReadStatements

public int getMaxConcurrentChannelMetaDataReadStatements()

Returns the maximum number of read statements that may be concurrently executed by the ChannelMetaDataDAO. Typically, these are read statements that load a channel configuration or information object or that look for pending channel operations. The default value is 64.

Returns:

maximum number of concurrently running read statements allowed for the ChannelMetaDataDAO.

setMaxConcurrentChannelMetaDataReadStatements

public void setMaxConcurrentChannelMetaDataReadStatements(int maxConcurrentChannelMetaDataReadStatements)

Sets the maximum number of read statements that may be concurrently executed by the ChannelMetaDataDAO. Typically, these are read statements that load a channel configuration or information object or that look for pending channel operations. The default value is 64.

Parameters:

maxConcurrentChannelMetaDataReadStatements - maximum number of concurrently running read statements allowed for the ChannelMetaDataDAO. Must be greater than zero.

Throws:

IllegalArgumentException - if the specified value is less than one.

getMaxConcurrentChannelMetaDataWriteStatements

public int getMaxConcurrentChannelMetaDataWriteStatements()

Returns the maximum number of write statements that may be concurrently executed by the ChannelMetaDataDAO. Typically, these are write statements that modify a channel configuration and information object or that add or remove pending channel operations. These write statements typically are logged batch statements or light-weight transactions, so they are significantly more expensive than regular write statements. The default value is 16.

Returns:

maximum number of concurrently running write statements allowed for the ChannelMetaDataDAO.

setMaxConcurrentChannelMetaDataWriteStatements

public void setMaxConcurrentChannelMetaDataWriteStatements(int maxConcurrentChannelMetaDataWriteStatements)

Sets the maximum number of write statements that may be concurrently executed by the ChannelMetaDataDAO. Typically, these are write statements that modify a channel configuration and information object or that add or remove pending channel operations. These write statements typically are logged batch statements or light-weight transactions, so they are significantly more expensive than regular write statements. The default value is 16.

Parameters:

maxConcurrentChannelMetaDataWriteStatements - maximum number of concurrently running write statements allowed for the ChannelMetaDataDAO. Must be greater than zero.

Throws:

IllegalArgumentException - if the specified value is less than one.

getMaxConcurrentControlSystemSupportReadStatements

public int getMaxConcurrentControlSystemSupportReadStatements()

Returns the maximum number of read statements that may be concurrently executed by all ControlSystemSupports. Typically, these are read statements that read samples from a sample bucket. All ControlSystemSupports share the same session and thus all their statements contribute towards reaching this limit. The default value is 128.

Returns:

maximum number of concurrently running read statements allowed for all ControlSystemSupports.

setMaxConcurrentControlSystemSupportReadStatements

public void setMaxConcurrentControlSystemSupportReadStatements(int maxConcurrentControlSystemSupportReadStatements)

Sets the maximum number of read statements that may be concurrently executed by all ControlSystemSupports. Typically, these are read statements that read samples from a sample bucket. All ControlSystemSupports share the same session and thus all their statements contribute towards reaching this limit. The default value is 128.

Parameters:

maxConcurrentControlSystemSupportReadStatements - maximum number of concurrently running read statements allowed for all ControlSystemSupports.

Throws:

IllegalArgumentException - if the specified value is less than one.

getMaxConcurrentControlSystemSupportWriteStatements

public int getMaxConcurrentControlSystemSupportWriteStatements()

Returns the maximum number of write statements that may be concurrently executed by all ControlSystemSupports. Typically, these are write statements that write a single sample to a sample bucket, which means that this kind of statements is rather cheap. All ControlSystemSupports share the same session and thus all their statements contribute towards reaching this limit. The default value is 512.

Returns:

maximum number of concurrently running write statements allowed for all ControlSystemSupports.

setMaxConcurrentControlSystemSupportWriteStatements

public void setMaxConcurrentControlSystemSupportWriteStatements(int maxConcurrentControlSystemSupportWriteStatements)

Sets the maximum number of write statements that may be concurrently executed by all ControlSystemSupports. Typically, these are write statements that write a single sample to a sample bucket, which means that this kind of statements is rather cheap. All ControlSystemSupports share the same session and thus all their statements contribute towards reaching this limit. The default value is 512.

Parameters:

maxConcurrentControlSystemSupportWriteStatements - maximum number of concurrently running write statements allowed for all ControlSystemSupports.

Throws:

IllegalArgumentException - if the specified value is less than one.

getSampleDecimation

public SampleDecimationThrottlingProperties getSampleDecimation()

Returns the configuration properties that control the sample decimation process.

Returns:

configuration properties for throttling the sample decimation process.

setSampleDecimation

public void setSampleDecimation(SampleDecimationThrottlingProperties sampleDecimation)

Sets the configuration properties that control the sample decimation process.

Parameters:

sampleDecimation - configuration properties for throttling the sample decimation process.