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Aleksey Yeschenko commented on CASSANDRA-9673: ---------------------------------------------- Rebased against most recent trunk and made some minor changes, here: https://github.com/iamaleksey/cassandra/tree/9673-3.0. Didn't go very far. Removed {{BATCHLOG_MUTATION}} Stage that Carl and I think is no longer needed (but we'll bring it back if that's a mistake), and did some renames and minor cleanup of unused methods. Good work. There is only one real issue so far, with that fixed, we could commit as is, but I have a bunch of nits that'd be nice to address: we are not properly handling old-format batchlog mutations sent live from 2.1/2.2 nodes, during live upgrades. You need to modify {{MutationVerbHandler}} and add special treatment to mutations for the old batchlog table. Nits: 1. I would prefer {{BatchStoreMessage}} and {{BatchRemoveMessage}} to be dumb and only be concerned about serialization/deserialization. This means no {{getMutation()}} in either. For {{BatchRemoveMessage}}, the actual logic should be in {{BatchRemoveVerbHandler}}. 2. I would like to separate {{Batch}} and {{BatchStoreMessage}} and put actual saving to batchlog logic into a new {{Batch}} class - to be used both for local (MV) writes and proper BL remote writes. 3. If moved to {{Batch}} (and if not, too), I would prefer the mutation collections in them to only be set in the constructor. 4. Somehow we are calling {{LegacyBatchMigrator.convertBatchEntries()}} on every replay, reverting Branimir's changes, instead of explicitly only doing it once, upon first replay. I'm presuming that this is done as a workaround for the live upgrade issue. I would prefer that we moved the migration to {{CassandraDaemon.setup()}}, where legacy schema and hints migration already get called. > Improve batchlog write path > --------------------------- > > Key: CASSANDRA-9673 > URL: https://issues.apache.org/jira/browse/CASSANDRA-9673 > Project: Cassandra > Issue Type: Improvement > Reporter: Aleksey Yeschenko > Assignee: Stefania > Labels: performance > Fix For: 3.0 beta 2 > > Attachments: 9673_001.tar.gz, 9673_004.tar.gz, > gc_times_first_node_patched_004.png, gc_times_first_node_trunk_004.png > > > Currently we allocate an on-heap {{ByteBuffer}} to serialize the batched > mutations into, before sending it to a distant node, generating unnecessary > garbage (potentially a lot of it). > With materialized views using the batchlog, it would be nice to optimise the > write path: > - introduce a new verb ({{Batch}}) > - introduce a new message ({{BatchMessage}}) that would encapsulate the > mutations, expiration, and creation time (similar to {{HintMessage}} in > CASSANDRA-6230) > - have MS serialize it directly instead of relying on an intermediate buffer > To avoid merely shifting the temp buffer to the receiving side(s) we should > change the structure of the batchlog table to use a list or a map of > individual mutations. -- This message was sent by Atlassian JIRA (v6.3.4#6332)