Move caching of the store to IndexShard. #30817
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In spite of the existing caching, I have seen a number of nodes hot threads where one thread had been spending all its cpu on computing the size of a directory. I am proposing to move the caching of the store size to `IndexShard` so that it has access to the existing logic regarding whether a shard is active or not in order to be able to cache the store size more agressively. The tricky bit is that an inactive shard might still be merged, which may have a significant impact on the store size. This should be especially useful for time-based data since most indices are typically inactive.
jpountz
added
>enhancement
WIP
:Distributed Indexing/Store
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Pinging @elastic/es-distributed |
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WIP because of the lack of test. |
s1monw
reviewed
May 24, 2018
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| private final MeanMetric totalMerges = new MeanMetric(); | ||
| private final CounterMetric totalMergesNumDocs = new CounterMetric(); | ||
| private final CounterMetric totalMergesSizeInBytes = new CounterMetric(); | ||
| private final CounterMetric currentMerges = new CounterMetric(); | ||
| private final AtomicLong currentMerges = new AtomicLong(); |
| @@ -66,11 +69,14 @@ | |||
| private final Set<OnGoingMerge> onGoingMerges = ConcurrentCollections.newConcurrentSet(); | |||
| private final Set<OnGoingMerge> readOnlyOnGoingMerges = Collections.unmodifiableSet(onGoingMerges); | |||
| private final MergeSchedulerConfig config; | |||
| private volatile long lastMergeMillis; | |||
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I don't think we need these changes. I guess it would be enough to check Engine#getMergeStats() and then do:
mergeStats.current > 0 || mergeStats.total != previousStats.total?
| } | ||
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| @Override | ||
| protected boolean needsRefresh() { |
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I am not sure why this is so complex, wouldn't it be enough to override needsRefresh()?
private MergeStats previousStats = new MergeStats();
if (super.needsRefresh()) {
boolean refresh = false;
if (isActive()) {
MergeStats mergeStats = getEngine().getMergeStats();
refresh = mergeStats.current > 0 || mergeStats.total != previousStats.total;
previousStats = mergeStats;
}
return refresh;
}| if (active.get() == false) { | ||
| // We refresh when transitioning to an inactive state to make | ||
| // it easier to cache the store size. | ||
| refresh("transition to inactive"); |
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-1 we should not refresh anything except of the internal reader. Visibility guarantees are important.
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Closed in favor of the original PR. |
jpountz
removed
:Distributed Indexing/Store
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In spite of the existing caching, I have seen a number of nodes hot threads
where one thread had been spending all its cpu on computing the size of a
directory. I am proposing to move the caching of the store size to
IndexShardso that it has access to the existing logic regarding whether a shard is active
or not in order to be able to cache the store size more agressively.
The tricky bit is that an inactive shard might still be merged, which may have
a significant impact on the store size.
This should be especially useful for time-based data since most indices are
typically inactive.