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Benedict commented on CASSANDRA-7546: ------------------------------------- I've uploaded a patch [here|https://github.com/belliottsmith/cassandra/tree/7964-simultinserts], and another [here|https://github.com/belliottsmith/cassandra/tree/7964+7926] which combines it with another stress patch that reduces the risk of OOM (although this risk is pretty low, and almost certainly not what you were hitting) - but as you scale thread count up it becomes more of a risk The main 7964 patch includes a couple of small bug fixes as well, and I've tested it against your schema and some other related schemas that are trickier to process. One thing I would suggest considering is expanding the clustering column count to increase the speed of generation, as 1200 items is still quite a few to create for only sending 1 item, which might end up reducing contention server side. Possibly reduce to only 30-40 items per tier. > AtomicSortedColumns.addAllWithSizeDelta has a spin loop that allocates memory > ----------------------------------------------------------------------------- > > Key: CASSANDRA-7546 > URL: https://issues.apache.org/jira/browse/CASSANDRA-7546 > Project: Cassandra > Issue Type: Bug > Components: Core > Reporter: graham sanderson > Assignee: graham sanderson > Fix For: 2.1.1 > > Attachments: 7546.20.txt, 7546.20_2.txt, 7546.20_3.txt, > 7546.20_4.txt, 7546.20_5.txt, 7546.20_6.txt, 7546.20_7.txt, 7546.20_7b.txt, > 7546.20_alt.txt, 7546.20_async.txt, 7546.21_v1.txt, hint_spikes.png, > suggestion1.txt, suggestion1_21.txt, young_gen_gc.png > > > In order to preserve atomicity, this code attempts to read, clone/update, > then CAS the state of the partition. > Under heavy contention for updating a single partition this can cause some > fairly staggering memory growth (the more cores on your machine the worst it > gets). > Whilst many usage patterns don't do highly concurrent updates to the same > partition, hinting today, does, and in this case wild (order(s) of magnitude > more than expected) memory allocation rates can be seen (especially when the > updates being hinted are small updates to different partitions which can > happen very fast on their own) - see CASSANDRA-7545 > It would be best to eliminate/reduce/limit the spinning memory allocation > whilst not slowing down the very common un-contended case. -- This message was sent by Atlassian JIRA (v6.3.4#6332)