# High CPU usage because lucene merge thread **URL:** \ **Category:** Elasticsearch\ **Created:** [June 17, 2021, 2:02am UTC](https://discuss.elastic.co/t/high-cpu-usage-because-lucene-merge-thread/276209 "2021-06-17T02:02:08Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![yeziblo](https://avatars.discourse-cdn.com/v4/letter/y/74df32/32.png) [@yeziblo](https://discuss.elastic.co/u/yeziblo)\ **Post date:** [June 17, 2021, 2:02am UTC](https://discuss.elastic.co/t/high-cpu-usage-because-lucene-merge-thread/276209/1 "2021-06-17T02:02:08Z")
My operation process is as follows: At 3 am everyday, program try to index data to ES, that usually takes 3 hours. During the indexing process, I will set the number\_of\_replicas parameter to 0, and when data indexing is completed, I will change the number\_of\_replicas to 1, and then wait for cluster health turn to green. at last, I change the index alias from the previous index (created on previous day) to point to the newly created index. During the whole indexing process, the CPU usage of ES cluster was always normal, but when the alias switch complete, the CPU usage suddenly increased. by using the hot\_thread API, I saw a lot of Lucene Merge threads. The ES version I used was 7.8.1, Cluster have six nodes and each nodes have 16G heap memory. the disk usage is well and disk type is SSD. the index size is 55G. I tried to change the index.merge.schedular.max\_thread\_count parameter to 1, but it doesn't seem to improve. Any suggestions are needed. Best regards. ---
**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\ **Post date:** [June 17, 2021, 2:03am UTC](https://discuss.elastic.co/t/high-cpu-usage-because-lucene-merge-thread/276209/2 "2021-06-17T02:03:24Z")
Is it causing issues? ---
**Author:** ![yeziblo](https://avatars.discourse-cdn.com/v4/letter/y/74df32/32.png) [@yeziblo](https://discuss.elastic.co/u/yeziblo)\ **Post date:** [June 17, 2021, 2:15am UTC](https://discuss.elastic.co/t/high-cpu-usage-because-lucene-merge-thread/276209/3 "2021-06-17T02:15:23Z")
Yes, some requests to query ES will return 502 errors ---
**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\ **Post date:** [June 17, 2021, 2:16am UTC](https://discuss.elastic.co/t/high-cpu-usage-because-lucene-merge-thread/276209/4 "2021-06-17T02:16:39Z")
What is the output from the `_cluster/stats?pretty&human` API? Can you post the hot threads and Elasticsearch logs from the time this happens? ---
**Author:** ![yeziblo](https://avatars.discourse-cdn.com/v4/letter/y/74df32/32.png) [@yeziblo](https://discuss.elastic.co/u/yeziblo)\ **Post date:** [June 17, 2021, 2:55am UTC](https://discuss.elastic.co/t/high-cpu-usage-because-lucene-merge-thread/276209/5 "2021-06-17T02:55:19Z")
the output is: ```auto { "_nodes" : { "total" : 6, "successful" : 6, "failed" : 0 }, "cluster_name" : "cluster", "timestamp" : 1623897005490, "status" : "green", "indices" : { "count" : 58, "shards" : { "total" : 339, "primaries" : 181, "replication" : 0.8729281767955801, "index" : { "shards" : { "min" : 2, "max" : 32, "avg" : 5.844827586206897 }, "primaries" : { "min" : 1, "max" : 16, "avg" : 3.1206896551724137 }, "replication" : { "min" : 0.0, "max" : 2.0, "avg" : 0.9655172413793104 } } }, "docs" : { "count" : 320479456, "deleted" : 49848119 }, "store" : { "size" : "1.4tb", "size_in_bytes" : 1561367960432 }, "fielddata" : { "memory_size" : "1.9gb", "memory_size_in_bytes" : 2140146480, "evictions" : 0 }, "query_cache" : { "memory_size" : "4.9gb", "memory_size_in_bytes" : 5315294942, "total_count" : 12515270180, "hit_count" : 2377814364, "miss_count" : 10137455816, "cache_size" : 415249, "cache_count" : 60055189, "evictions" : 59639940 }, "completion" : { "size" : "0b", "size_in_bytes" : 0 }, "segments" : { "count" : 4101, "memory" : "348.6mb", "memory_in_bytes" : 365606982, "terms_memory" : "242.3mb", "terms_memory_in_bytes" : 254158536, "stored_fields_memory" : "7.9mb", "stored_fields_memory_in_bytes" : 8376536, "term_vectors_memory" : "0b", "term_vectors_memory_in_bytes" : 0, "norms_memory" : "50.9mb", "norms_memory_in_bytes" : 53434880, "points_memory" : "0b", "points_memory_in_bytes" : 0, "doc_values_memory" : "47.3mb", "doc_values_memory_in_bytes" : 49637030, "index_writer_memory" : "1.7gb", "index_writer_memory_in_bytes" : 1871176000, "version_map_memory" : "68.2mb", "version_map_memory_in_bytes" : 71529626, "fixed_bit_set" : "1.3mb", "fixed_bit_set_memory_in_bytes" : 1460736, "max_unsafe_auto_id_timestamp" : 1623888002457, "file_sizes" : { } }, "mappings" : { "field_types" : [ { "name" : "binary", "count" : 3, "index_count" : 1 }, { "name" : "boolean", "count" : 443, "index_count" : 42 }, { "name" : "date", "count" : 370, "index_count" : 50 }, { "name" : "double", "count" : 48, "index_count" : 15 }, { "name" : "flattened", "count" : 1, "index_count" : 1 }, { "name" : "float", "count" : 420, "index_count" : 23 }, { "name" : "geo_point", "count" : 15, "index_count" : 15 }, { "name" : "geo_shape", "count" : 1, "index_count" : 1 }, { "name" : "half_float", "count" : 56, "index_count" : 14 }, { "name" : "integer", "count" : 1915, "index_count" : 31 }, { "name" : "keyword", "count" : 2661, "index_count" : 57 }, { "name" : "long", "count" : 1499, "index_count" : 48 }, { "name" : "nested", "count" : 68, "index_count" : 20 }, { "name" : "object", "count" : 1520, "index_count" : 37 }, { "name" : "search_as_you_type", "count" : 5, "index_count" : 5 }, { "name" : "short", "count" : 1, "index_count" : 1 }, { "name" : "text", "count" : 7627, "index_count" : 42 } ] }, "analysis" : { "char_filter_types" : [ { "name" : "pattern_replace", "count" : 34, "index_count" : 19 } ], "tokenizer_types" : [ { "name" : "pattern", "count" : 45, "index_count" : 15 } ], "filter_types" : [ { "name" : "edgeNGram", "count" : 15, "index_count" : 15 }, { "name" : "synonym", "count" : 26, "index_count" : 20 } ], "analyzer_types" : [ { "name" : "custom", "count" : 170, "index_count" : 20 } ], "built_in_char_filters" : [], "built_in_tokenizers" : [ { "name" : "keyword", "count" : 60, "index_count" : 15 }, { "name" : "standard", "count" : 50, "index_count" : 20 } ], "built_in_filters" : [ { "name" : "lowercase", "count" : 155, "index_count" : 20 }, { "name" : "stop", "count" : 15, "index_count" : 15 }, { "name" : "trim", "count" : 30, "index_count" : 15 } ], "built_in_analyzers" : [] } }, "nodes" : { "count" : { "total" : 6, "coordinating_only" : 0, "data" : 6, "ingest" : 6, "master" : 6, "ml" : 6, "remote_cluster_client" : 6, "transform" : 6, "voting_only" : 0 }, "versions" : [ "7.8.1" ], "os" : { "available_processors" : 40, "allocated_processors" : 40, "names" : [ { "name" : "Linux", "count" : 6 } ], "pretty_names" : [ { "pretty_name" : "CentOS Linux 7 (Core)", "count" : 6 } ], "mem" : { "total" : "0b", "total_in_bytes" : 0, "free" : "1.2gb", "free_in_bytes" : 1312112640, "used" : "0b", "used_in_bytes" : 0, "free_percent" : 0, "used_percent" : 0 } }, "process" : { "cpu" : { "percent" : 416 }, "open_file_descriptors" : { "min" : 772, "max" : 1630, "avg" : 996 } }, "jvm" : { "max_uptime" : "32.9d", "max_uptime_in_millis" : 2848484285, "versions" : [ { "version" : "14.0.1", "vm_name" : "OpenJDK 64-Bit Server VM", "vm_version" : "14.0.1+7", "vm_vendor" : "AdoptOpenJDK", "bundled_jdk" : true, "using_bundled_jdk" : true, "count" : 6 } ], "mem" : { "heap_used" : "43.1gb", "heap_used_in_bytes" : 46335750144, "heap_max" : "80gb", "heap_max_in_bytes" : 85899345920 }, "threads" : 1086 }, "fs" : { "total" : "2.6tb", "total_in_bytes" : 2958485848064, "free" : "1.2tb", "free_in_bytes" : 1364500041728, "available" : "1.1tb", "available_in_bytes" : 1214075523072 }, "plugins" : [], "network_types" : { "transport_types" : { "netty4" : 6 }, "http_types" : { "netty4" : 6 } }, "discovery_types" : { "zen" : 6 }, "packaging_types" : [ { "flavor" : "default", "type" : "docker", "count" : 6 } ], "ingest" : { "number_of_pipelines" : 2, "processor_stats" : { "gsub" : { "count" : 0, "failed" : 0, "current" : 0, "time" : "0s", "time_in_millis" : 0 }, "script" : { "count" : 0, "failed" : 0, "current" : 0, "time" : "0s", "time_in_millis" : 0 } } } } } ``` ---
**Author:** ![yeziblo](https://avatars.discourse-cdn.com/v4/letter/y/74df32/32.png) [@yeziblo](https://discuss.elastic.co/u/yeziblo)\ **Post date:** [June 17, 2021, 3:01am UTC](https://discuss.elastic.co/t/high-cpu-usage-because-lucene-merge-thread/276209/6 "2021-06-17T03:01:36Z")
the hot threads: ```auto ::: {es02}{dilmrt}{ml.machine_memory=9223372036854771712, rack=r1, ml.max_open_jobs=20, xpack.installed=true, transform.node=true} Hot threads at 2021-06-09T09:13:52.863Z, interval=500ms, busiestThreads=3, ignoreIdleThreads=true: 84.1% (420.2ms out of 500ms) cpu usage by thread 'elasticsearch[es02][[fysearch20210609070500][0]: Lucene Merge Thread #9]' 3/10 snapshots sharing following 14 elements app//org.apache.lucene.util.compress.LZ4.encodeLiterals(LZ4.java:159) app//org.apache.lucene.util.compress.LZ4.encodeSequence(LZ4.java:172) 3/10 snapshots sharing following 14 elements app//org.apache.lucene.util.compress.LZ4.encodeLiterals(LZ4.java:151) app//org.apache.lucene.util.compress.LZ4.encodeSequence(LZ4.java:172) 4/10 snapshots sharing following 7 elements app//org.apache.lucene.index.SegmentMerger.mergeFields(SegmentMerger.java:229) app//org.apache.lucene.index.SegmentMerger.merge(SegmentMerger.java:106) 56.6% (282.8ms out of 500ms) cpu usage by thread 'elasticsearch[es02][[fysearch20210609070500][4]: Lucene Merge Thread #0]' 4/10 snapshots sharing following 14 elements app//org.apache.lucene.util.compress.LZ4.encodeLiterals(LZ4.java:151) app//org.apache.lucene.util.compress.LZ4.encodeSequence(LZ4.java:172) app//org.apache.lucene.util.compress.LZ4.compress(LZ4.java:441) 2/10 snapshots sharing following 14 elements app//org.apache.lucene.util.compress.LZ4.encodeLiterals(LZ4.java:159) app//org.apache.lucene.util.compress.LZ4.encodeSequence(LZ4.java:172) app//org.apache.lucene.util.compress.LZ4.compress(LZ4.java:441) 2/10 snapshots sharing following 11 elements app//org.apache.lucene.codecs.compressing.CompressingStoredFieldsReader$BlockState.reset(CompressingStoredFieldsReader.java:393) 2/10 snapshots sharing following 7 elements app//org.apache.lucene.index.SegmentMerger.mergeFields(SegmentMerger.java:229) app//org.apache.lucene.index.SegmentMerger.merge(SegmentMerger.java:106) app//org.apache.lucene.index.IndexWriter.mergeMiddle(IndexWriter.java:4463) 53.0% (264.8ms out of 500ms) cpu usage by thread 'elasticsearch[es02][[fysearch20210609070500][2]: Lucene Merge Thread #8]' 6/10 snapshots sharing following 14 elements app//org.elasticsearch.index.engine.ElasticsearchConcurrentMergeScheduler.doMerge(ElasticsearchConcurrentMergeScheduler.java:101) app//org.apache.lucene.index.ConcurrentMergeScheduler$MergeThread.run(ConcurrentMergeScheduler.java:662) 2/10 snapshots sharing following 13 elements app//org.apache.lucene.util.compress.LZ4.encodeSequence(LZ4.java:172) app//org.apache.lucene.util.compress.LZ4.compress(LZ4.java:441) 2/10 snapshots sharing following 13 elements app//org.apache.lucene.util.compress.LZ4.encodeSequence(LZ4.java:177) ::: {es06}{dilmrt}{ml.machine_memory=9223372036854771712, rack=r1, ml.max_open_jobs=20, xpack.installed=true, transform.node=true} Hot threads at 2021-06-09T09:13:52.882Z, interval=500ms, busiestThreads=3, ignoreIdleThreads=true: 38.0% (190ms out of 500ms) cpu usage by thread 'elasticsearch[es06][[fysearch20210609070500][3]: Lucene Merge Thread #9]' 5/10 snapshots sharing following 14 elements app//org.apache.lucene.util.compress.LZ4.encodeLiterals(LZ4.java:151) app//org.apache.lucene.util.compress.LZ4.compress(LZ4.java:441) 3/10 snapshots sharing following 14 elements app//org.apache.lucene.util.compress.LZ4.encodeLiterals(LZ4.java:159) app//org.apache.lucene.util.compress.LZ4.compress(LZ4.java:441) 2/10 snapshots sharing following 11 elements app//org.apache.lucene.codecs.compressing.CompressingStoredFieldsReader$BlockState.reset(CompressingStoredFieldsReader.java:393) app//org.apache.lucene.codecs.compressing.CompressingStoredFieldsReader.document(CompressingStoredFieldsReader.java:572) 34.3% (171.3ms out of 500ms) cpu usage by thread 'elasticsearch[es06][[suggestion@fysearch20210609070500][3]: Lucene Merge Thread #14]' 2/10 snapshots sharing following 18 elements java.base@14.0.1/sun.nio.ch.FileChannelImpl.readInternal(FileChannelImpl.java:817) java.base@14.0.1/sun.nio.ch.FileChannelImpl.read(FileChannelImpl.java:802) app//org.apache.lucene.store.NIOFSDirectory$NIOFSIndexInput.readInternal(NIOFSDirectory.java:179) 5/10 snapshots sharing following 14 elements app//org.apache.lucene.util.compress.LZ4.encodeLiterals(LZ4.java:151) app//org.apache.lucene.util.compress.LZ4.encodeSequence(LZ4.java:172) 2/10 snapshots sharing following 12 elements app//org.apache.lucene.codecs.compressing.CompressionMode$4.decompress(CompressionMode.java:139) unique snapshot app//org.apache.lucene.util.compress.LZ4.encodeSequence(LZ4.java:177) 34.2% (171.1ms out of 500ms) cpu usage by thread 'elasticsearch[es06][write][T#4]' 2/10 snapshots sharing following 49 elements app//org.apache.lucene.util.fst.ByteSequenceOutputs.read(ByteSequenceOutputs.java:35) app//org.apache.lucene.util.fst.FST.readArc(FST.java:1260) app//org.apache.lucene.util.fst.FST.readArcByDirectAddressing(FST.java:1211) 2/10 snapshots sharing following 35 elements app//org.elasticsearch.index.shard.IndexShard.get(IndexShard.java:948) app//org.elasticsearch.index.get.ShardGetService.innerGet(ShardGetService.java:180) 2/10 snapshots sharing following 36 elements app//org.elasticsearch.index.translog.TranslogWriter.add(TranslogWriter.java:171) app//org.elasticsearch.index.translog.Translog.add(Translog.java:544) 2/10 snapshots sharing following 42 elements app//org.apache.lucene.index.DefaultIndexingChain.processField(DefaultIndexingChain.java:442) app//org.apache.lucene.index.DocumentsWriterPerThread.updateDocument(DocumentsWriterPerThread.java:250) 2/10 snapshots sharing following 29 elements app//org.elasticsearch.action.bulk.TransportShardBulkAction$2.doRun(TransportShardBulkAction.java:157) app//org.elasticsearch.action.bulk.TransportShardBulkAction.performOnPrimary(TransportShardBulkAction.java:202) ::: {es01}{dilmrt}{ml.machine_memory=9223372036854771712, rack=r1, xpack.installed=true, transform.node=true, ml.max_open_jobs=20} Hot threads at 2021-06-09T09:13:52.854Z, interval=500ms, busiestThreads=3, ignoreIdleThreads=true: 62.5% (312.6ms out of 500ms) cpu usage by thread 'elasticsearch[es01][write][T#7]' 2/10 snapshots sharing following 45 elements app//org.apache.lucene.index.FieldUpdatesBuffer$BufferedUpdateIterator.nextTerm(FieldUpdatesBuffer.java:350) app//org.apache.lucene.index.FieldUpdatesBuffer$BufferedUpdateIterator.next(FieldUpdatesBuffer.java:317) app//org.apache.lucene.index.FrozenBufferedUpdates.applyDocValuesUpdates(FrozenBufferedUpdates.java:496) 2/10 snapshots sharing following 45 elements app//org.apache.lucene.codecs.blocktree.SegmentTermsEnum.seekCeil(SegmentTermsEnum.java:742) app//org.apache.lucene.index.FrozenBufferedUpdates$TermDocsIterator.nextTerm(FrozenBufferedUpdates.java:829) 2/10 snapshots sharing following 48 elements app//org.apache.lucene.util.compress.LZ4.decompress(LZ4.java:103) app//org.apache.lucene.codecs.blocktree.CompressionAlgorithm$3.read(CompressionAlgorithm.java:51) 2/10 snapshots sharing following 44 elements app//org.apache.lucene.index.FrozenBufferedUpdates$TermDocsIterator.nextTerm(FrozenBufferedUpdates.java:829) app//org.apache.lucene.index.FrozenBufferedUpdates.applyDocValuesUpdates(FrozenBufferedUpdates.java:507) 2/10 snapshots sharing following 44 elements app//org.apache.lucene.index.FieldUpdatesBuffer$BufferedUpdateIterator.next(FieldUpdatesBuffer.java:317) app//org.apache.lucene.index.FrozenBufferedUpdates.applyDocValuesUpdates(FrozenBufferedUpdates.java:496) 56.2% (281ms out of 500ms) cpu usage by thread 'elasticsearch[es01][[suggestion@fysearch20210609070500][3]: Lucene Merge Thread #55]' 3/10 snapshots sharing following 12 elements app//org.apache.lucene.codecs.blocktree.BlockTreeTermsWriter$TermsWriter.pushTerm(BlockTreeTermsWriter.java:977) app//org.apache.lucene.codecs.blocktree.BlockTreeTermsWriter$TermsWriter.write(BlockTreeTermsWriter.java:942) 3/10 snapshots sharing following 13 elements app//org.apache.lucene.index.MappedMultiFields$MappedMultiTermsEnum.postings(MappedMultiFields.java:127) app//org.apache.lucene.codecs.PushPostingsWriterBase.writeTerm(PushPostingsWriterBase.java:127) 4/10 snapshots sharing following 9 elements app//org.apache.lucene.codecs.FieldsConsumer.merge(FieldsConsumer.java:105) app//org.apache.lucene.codecs.perfield.PerFieldPostingsFormat$FieldsWriter.merge(PerFieldPostingsFormat.java:197) 55.1% (275.4ms out of 500ms) cpu usage by thread 'elasticsearch[es01][[suggestion@fysearch20210609070500][3]: Lucene Merge Thread #48]' 3/10 snapshots sharing following 14 elements app//org.apache.lucene.store.DataOutput.writeVInt(DataOutput.java:191) app//org.apache.lucene.codecs.lucene84.Lucene84PostingsWriter.finishTerm(Lucene84PostingsWriter.java:416) app//org.apache.lucene.codecs.PushPostingsWriterBase.writeTerm(PushPostingsWriterBase.java:174) 2/10 snapshots sharing following 14 elements app//org.apache.lucene.codecs.lucene84.ForDeltaUtil.encodeDeltas(ForDeltaUtil.java:67) app//org.apache.lucene.codecs.lucene84.Lucene84PostingsWriter.startDoc(Lucene84PostingsWriter.java:243) 4/10 snapshots sharing following 10 elements app//org.apache.lucene.codecs.blocktree.BlockTreeTermsWriter.write(BlockTreeTermsWriter.java:347) unique snapshot app//org.apache.lucene.index.MultiTermsEnum.pushTop(MultiTermsEnum.java:275) ::: {es03}{dilmrt}{ml.machine_memory=9223372036854771712, rack=r1, ml.max_open_jobs=20, xpack.installed=true, transform.node=true} Hot threads at 2021-06-09T09:13:52.854Z, interval=500ms, busiestThreads=3, ignoreIdleThreads=true: 33.9% (169.3ms out of 500ms) cpu usage by thread 'elasticsearch[es03][search][T#8]' 4/10 snapshots sharing following 6 elements app//org.elasticsearch.common.util.concurrent.TimedRunnable.doRun(TimedRunnable.java:44) app//org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingAbstractRunnable.doRun(ThreadContext.java:695) 6/10 snapshots sharing following 10 elements java.base@14.0.1/jdk.internal.misc.Unsafe.park(Native Method) java.base@14.0.1/java.util.concurrent.locks.LockSupport.park(LockSupport.java:211) 33.4% (166.7ms out of 500ms) cpu usage by thread 'elasticsearch[es03][write][T#2]' 6/10 snapshots sharing following 44 elements app//org.apache.lucene.codecs.blocktree.BlockTreeTermsWriter$TermsWriter.write(BlockTreeTermsWriter.java:937) app//org.apache.lucene.codecs.blocktree.BlockTreeTermsWriter.write(BlockTreeTermsWriter.java:347) 2/10 snapshots sharing following 48 elements app//org.apache.lucene.util.compress.LZ4.compress(LZ4.java:432) app//org.apache.lucene.codecs.blocktree.BlockTreeTermsWriter$TermsWriter.writeBlock(BlockTreeTermsWriter.java:853) 2/10 snapshots sharing following 45 elements app//org.apache.lucene.codecs.blocktree.BlockTreeTermsWriter$TermsWriter.pushTerm(BlockTreeTermsWriter.java:977) app//org.apache.lucene.codecs.blocktree.BlockTreeTermsWriter$TermsWriter.write(BlockTreeTermsWriter.java:942) 33.2% (165.8ms out of 500ms) cpu usage by thread 'elasticsearch[es03][[fysearch20210609070500][0]: Lucene Merge Thread #1]' 3/10 snapshots sharing following 17 elements app//org.apache.lucene.codecs.lucene80.IndexedDISI.advance(IndexedDISI.java:384) app//org.apache.lucene.codecs.lucene80.IndexedDISI.nextDoc(IndexedDISI.java:459) 2/10 snapshots sharing following 12 elements app//org.apache.lucene.codecs.NormsConsumer$1$1.nextDoc(NormsConsumer.java:146) app//org.apache.lucene.codecs.lucene80.Lucene80NormsConsumer.writeValues(Lucene80NormsConsumer.java:145) app//org.apache.lucene.codecs.lucene80.Lucene80NormsConsumer.addNormsField(Lucene80NormsConsumer.java:126) 3/10 snapshots sharing following 10 elements app//org.apache.lucene.codecs.lucene80.Lucene80NormsConsumer.addNormsField(Lucene80NormsConsumer.java:111) app//org.apache.lucene.codecs.NormsConsumer.mergeNormsField(NormsConsumer.java:108) 2/10 snapshots sharing following 15 elements app//org.apache.lucene.util.packed.MonotonicLongValues.get(MonotonicLongValues.java:40) app//org.apache.lucene.util.packed.PackedLongValues.get(PackedLongValues.java:108) ``` ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 15, 2021, 3:01am UTC](https://discuss.elastic.co/t/high-cpu-usage-because-lucene-merge-thread/276209/7 "2021-07-15T03:01:55Z")
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