Class 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, EsExecutors.allocatedProcessors(Settings) / 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 Details


      public static final Setting<Integer> MAX_THREAD_COUNT_SETTING

      public static final Setting<Integer> MAX_MERGE_COUNT_SETTING

      public static final Setting<Boolean> AUTO_THROTTLE_SETTING
  • Method Details

    • isAutoThrottle

      public boolean isAutoThrottle()
      Returns true iff auto throttle is enabled.
      See Also:
      • ConcurrentMergeScheduler.enableAutoIOThrottle()
    • getMaxThreadCount

      public int getMaxThreadCount()
      Returns maxThreadCount.
    • getMaxMergeCount

      public int getMaxMergeCount()
      Returns maxMergeCount.