# Switching back to ConcurrentMergeScheduler **URL:** \ **Category:** Elasticsearch\ **Created:** [April 18, 2014, 7:01pm UTC](https://discuss.elastic.co/t/switching-back-to-concurrentmergescheduler/17085 "2014-04-18T19:01:06Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![David\_Smith\_2](https://avatars.discourse-cdn.com/v4/letter/d/a9a28c/32.png) [@David\_Smith\_2](https://discuss.elastic.co/u/David_Smith_2)\ **Post date:** [April 18, 2014, 7:01pm UTC](https://discuss.elastic.co/t/switching-back-to-concurrentmergescheduler/17085/1 "2014-04-18T19:01:06Z")
I see that ES switch back to ConcurrentMergeScheduler in 1.1.1 due to it affecting indexing performance in 1.1.0. > We're on 1.1.0 and cannot upgrade to 1.1.1 for the time being. Is there a way to switch it back using the API? I tried the following command, but it seems to not take. curl -i -XPUT localhost:9200/\_cluster/settings -d '{ "persistent": { "index.merge.scheduler.type": "org.elasticsearch.index.merge.scheduler.ConcurrentMergeSchedulerProvider" } }' HTTP/1.1 200 OK Content-Type: application/json; charset=UTF-8 Content-Length: 52 {"acknowledged":true,"persistent":{},"transient":{}} It does not seem to be set when I try to re-GET it (and no errors in logs at DEBUG level or above). curl -i -XGET localhost:9200/\_cluster/settings HTTP/1.1 200 OK Content-Type: application/json; charset=UTF-8 Content-Length: 66 {"persistent":{"threadpool":{"bulk":{"size":"8"}}},"transient":{}} Am using the wrong way of specifying the scheduler? I also tried just specifying ConcurrentMergeSchedulerProvider instead of the full class name, but that didn't work. Any ideas? David -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/601a831d-2c8e-4615-b816-435a6d4e4d9c%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/601a831d-2c8e-4615-b816-435a6d4e4d9c%40googlegroups.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![jprante](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jprante/32/44941_2.png) [@jprante](https://discuss.elastic.co/u/jprante)\ **Post date:** [April 19, 2014, 8:48am UTC](https://discuss.elastic.co/t/switching-back-to-concurrentmergescheduler/17085/2 "2014-04-19T08:48:48Z")
I use this on 1.1.0 in my config/elasticsearch.yml index: merge: scheduler: type: concurrent max\_thread\_count: 4 policy: type: tiered max\_merged\_segment: 1gb segments\_per\_tier: 4 max\_merge\_at\_once: 4 max\_merge\_at\_once\_explicit: 4 threadpool: merge: type: fixed size: 4 queue\_size: 32 Explanation: - use concurrent scheduler and limit it to 4 threads. I find 4 threads being able to keep up with the highest bulk insertion rate I could generate - use tiered policy (the default, it is most flexible in selecting segments to merge) - create segments less than 1gb in a tier (this limits the file size of the segments files, the smaller the files, the faster the merges, but the more files are created) - create 4 segments per tier (do not create segments numbers that are too high per tier) - merge 4 segments at each merge step (this limits the total run time and resource consumption of a segment merge step) - also limit merge for explicit \_optimize API call - extend thread pool to 4 merge threads with a maximum of 32 merge operations in the queue (32 should be sufficient to handle outstanding merges) From time to time, if the number of files get very high (\>500) and index is calm (no indexing, no heavy search), I do a manual \_optimize. Jörg On Fri, Apr 18, 2014 at 9:01 PM, David Smith [davidksmith2k@gmail.com](mailto:davidksmith2k@gmail.com)wrote: > I see that ES switch back to ConcurrentMergeScheduler in 1.1.1 due to it > affecting indexing performance in 1.1.0. > [Switch back to ConcurrentMergeScheduler as the default · Issue #5817 · elastic/elasticsearch · GitHub](https://github.com/elasticsearch/elasticsearch/issues/5817) > > We're on 1.1.0 and cannot upgrade to 1.1.1 for the time being. Is there a > way to switch it back using the API? I tried the following command, but it > seems to not take. > > curl -i -XPUT localhost:9200/\_cluster/settings -d '{ "persistent": { > "index.merge.scheduler.type": > "org.elasticsearch.index.merge.scheduler.ConcurrentMergeSchedulerProvider" > } }' > HTTP/1.1 200 OK > Content-Type: application/json; charset=UTF-8 > Content-Length: 52 > > {"acknowledged":true,"persistent":{},"transient":{}} > > It does not seem to be set when I try to re-GET it (and no errors in logs > at DEBUG level or above). > > curl -i -XGET localhost:9200/\_cluster/settings > HTTP/1.1 200 OK > Content-Type: application/json; charset=UTF-8 > Content-Length: 66 > > {"persistent":{"threadpool":{"bulk":{"size":"8"}}},"transient":{}} > > Am using the wrong way of specifying the scheduler? I also tried just > specifying ConcurrentMergeSchedulerProvider instead of the full class > name, but that didn't work. > > Any ideas? > David > > -- > You received this message because you are subscribed to the Google Groups > "elasticsearch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). > To view this discussion on the web visit > [https://groups.google.com/d/msgid/elasticsearch/601a831d-2c8e-4615-b816-435a6d4e4d9c%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/601a831d-2c8e-4615-b816-435a6d4e4d9c%40googlegroups.com)[https://groups.google.com/d/msgid/elasticsearch/601a831d-2c8e-4615-b816-435a6d4e4d9c%40googlegroups.com?utm\_medium=email&utm\_source=footer](https://groups.google.com/d/msgid/elasticsearch/601a831d-2c8e-4615-b816-435a6d4e4d9c%40googlegroups.com?utm_medium=email&utm_source=footer) > . > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/CAKdsXoGwnPYyBPYRSPz5c9WGzfH68CHX7gXb7UwmgMbwXdOnMg%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAKdsXoGwnPYyBPYRSPz5c9WGzfH68CHX7gXb7UwmgMbwXdOnMg%40mail.gmail.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![David\_Smith\_2](https://avatars.discourse-cdn.com/v4/letter/d/a9a28c/32.png) [@David\_Smith\_2](https://discuss.elastic.co/u/David_Smith_2)\ **Post date:** [April 19, 2014, 1:22pm UTC](https://discuss.elastic.co/t/switching-back-to-concurrentmergescheduler/17085/3 "2014-04-19T13:22:56Z")
Thanks, Jörg. Is it possible to set these via API instead of changing the yaml? -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/bbf0936b-84eb-4e4a-b7c4-7fa2dcaad963%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/bbf0936b-84eb-4e4a-b7c4-7fa2dcaad963%40googlegroups.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![jprante](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jprante/32/44941_2.png) [@jprante](https://discuss.elastic.co/u/jprante)\ **Post date:** [April 19, 2014, 2:05pm UTC](https://discuss.elastic.co/t/switching-back-to-concurrentmergescheduler/17085/4 "2014-04-19T14:05:39Z")
No, you can not change the merge scheduler settings via API. Threadpool settings updating works. Jörg On Sat, Apr 19, 2014 at 3:22 PM, David Smith [davidksmith2k@gmail.com](mailto:davidksmith2k@gmail.com)wrote: > Thanks, Jörg. Is it possible to set these via API instead of changing the > yaml? > > -- > You received this message because you are subscribed to the Google Groups > "elasticsearch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). > To view this discussion on the web visit > [https://groups.google.com/d/msgid/elasticsearch/bbf0936b-84eb-4e4a-b7c4-7fa2dcaad963%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/bbf0936b-84eb-4e4a-b7c4-7fa2dcaad963%40googlegroups.com)[https://groups.google.com/d/msgid/elasticsearch/bbf0936b-84eb-4e4a-b7c4-7fa2dcaad963%40googlegroups.com?utm\_medium=email&utm\_source=footer](https://groups.google.com/d/msgid/elasticsearch/bbf0936b-84eb-4e4a-b7c4-7fa2dcaad963%40googlegroups.com?utm_medium=email&utm_source=footer) > . > > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/CAKdsXoF\_gH1iZsws1mNqNjtxLnkoEpn14Fs6o0DD5XtMqrKc7g%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAKdsXoF_gH1iZsws1mNqNjtxLnkoEpn14Fs6o0DD5XtMqrKc7g%40mail.gmail.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![David\_Smith\_2](https://avatars.discourse-cdn.com/v4/letter/d/a9a28c/32.png) [@David\_Smith\_2](https://discuss.elastic.co/u/David_Smith_2)\ **Post date:** [April 19, 2014, 4:19pm UTC](https://discuss.elastic.co/t/switching-back-to-concurrentmergescheduler/17085/5 "2014-04-19T16:19:00Z")
Ahh, got it. Thanks. On Saturday, April 19, 2014 10:05:39 AM UTC-4, Jörg Prante wrote: > No, you can not change the merge scheduler settings via API. Threadpool > settings updating works. > > Jörg > > On Sat, Apr 19, 2014 at 3:22 PM, David Smith \<[davidk...@gmail.com](mailto:davidk...@gmail.com)\ > > > wrote: > > > Thanks, Jörg. Is it possible to set these via API instead of changing the > > yaml? > > > > -- > > You received this message because you are subscribed to the Google Groups > > "elasticsearch" group. > > To unsubscribe from this group and stop receiving emails from it, send an > > email to [elasticsearc...@googlegroups.com](mailto:elasticsearc...@googlegroups.com) \. > > To view this discussion on the web visit > > [https://groups.google.com/d/msgid/elasticsearch/bbf0936b-84eb-4e4a-b7c4-7fa2dcaad963%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/bbf0936b-84eb-4e4a-b7c4-7fa2dcaad963%40googlegroups.com)[https://groups.google.com/d/msgid/elasticsearch/bbf0936b-84eb-4e4a-b7c4-7fa2dcaad963%40googlegroups.com?utm\_medium=email&utm\_source=footer](https://groups.google.com/d/msgid/elasticsearch/bbf0936b-84eb-4e4a-b7c4-7fa2dcaad963%40googlegroups.com?utm_medium=email&utm_source=footer) > > . > > > > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/040d8e5d-5a1a-4ffb-8c48-b39d59c14245%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/040d8e5d-5a1a-4ffb-8c48-b39d59c14245%40googlegroups.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 1:34am UTC](https://discuss.elastic.co/t/switching-back-to-concurrentmergescheduler/17085/6 "2017-07-06T01:34:49Z")