org.elasticsearch.index.shard

Class MergeSchedulerConfig

java.lang.Object

org.elasticsearch.index.shard.MergeSchedulerConfig

public final class MergeSchedulerConfig
extends Object

The merge scheduler (ConcurrentMergeScheduler) controls the execution of merge operations once they are needed (according to the merge policy). Merges run in separate threads, and when the maximum number of threads is reached, further merges will wait until a merge thread becomes available.

The merge scheduler supports the following dynamic settings:

• index.merge.scheduler.max_thread_count: The maximum number of threads that may be merging at once. Defaults to Math.max(1, Math.min(4, Runtime.getRuntime().availableProcessors() / 2)) which works well for a good solid-state-disk (SSD). If your index is on spinning platter drives instead, decrease this to 1.
• index.merge.scheduler.auto_throttle: If this is true (the default), then the merge scheduler will rate-limit IO (writes) for merges to an adaptive value depending on how many merges are requested over time. An application with a low indexing rate that unluckily suddenly requires a large merge will see that merge aggressively throttled, while an application doing heavy indexing will see the throttle move higher to allow merges to keep up with ongoing indexing.

Field Summary

Fields

Modifier and Type	Field and Description
static String	AUTO_THROTTLE
static String	MAX_MERGE_COUNT
static String	MAX_THREAD_COUNT
static String	NOTIFY_ON_MERGE_FAILURE

Constructor Summary

Constructors

Constructor and Description
MergeSchedulerConfig(Settings indexSettings)

Method Summary

Methods

Modifier and Type	Method and Description
int	getMaxMergeCount() Returns maxMergeCount.
int	getMaxThreadCount() Returns maxThreadCount.
boolean	isAutoThrottle() Returns true iff auto throttle is enabled.
boolean	isNotifyOnMergeFailure() Returns true iff we fail the engine on a merge failure.
void	setAutoThrottle(boolean autoThrottle) Enables / disables auto throttling on the ConcurrentMergeScheduler
void	setMaxMergeCount(int maxMergeCount) Expert: set the maximum number of simultaneous merges allowed.
void	setMaxThreadCount(int maxThreadCount) Expert: directly set the maximum number of merge threads and simultaneous merges allowed.

Methods inherited from class java.lang.Object

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

Field Detail

MAX_THREAD_COUNT

public static final String MAX_THREAD_COUNT

See Also:

Constant Field Values

MAX_MERGE_COUNT

public static final String MAX_MERGE_COUNT

See Also:

Constant Field Values

AUTO_THROTTLE

public static final String AUTO_THROTTLE

See Also:

Constant Field Values

NOTIFY_ON_MERGE_FAILURE

public static final String NOTIFY_ON_MERGE_FAILURE

See Also:

Constant Field Values

Constructor Detail

MergeSchedulerConfig

public MergeSchedulerConfig(Settings indexSettings)

Method Detail

isAutoThrottle

public boolean isAutoThrottle()

Returns true iff auto throttle is enabled.

See Also:

ConcurrentMergeScheduler.enableAutoIOThrottle()

setAutoThrottle

public void setAutoThrottle(boolean autoThrottle)

Enables / disables auto throttling on the ConcurrentMergeScheduler

getMaxThreadCount

public int getMaxThreadCount()

Returns maxThreadCount.

setMaxThreadCount

public void setMaxThreadCount(int maxThreadCount)

Expert: directly set the maximum number of merge threads and simultaneous merges allowed.

getMaxMergeCount

public int getMaxMergeCount()

Returns maxMergeCount.

setMaxMergeCount

public void setMaxMergeCount(int maxMergeCount)

Expert: set the maximum number of simultaneous merges allowed.

isNotifyOnMergeFailure

public boolean isNotifyOnMergeFailure()

Returns true iff we fail the engine on a merge failure. Default is true