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Posted to commits@cassandra.apache.org by "Alex Petrov (JIRA)" <ji...@apache.org> on 2016/12/01 20:02:58 UTC
[jira] [Comment Edited] (CASSANDRA-12956) CL is not replayed on
custom 2i exception
[ https://issues.apache.org/jira/browse/CASSANDRA-12956?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15708453#comment-15708453 ]
Alex Petrov edited comment on CASSANDRA-12956 at 12/1/16 8:02 PM:
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Patch for {{3.0}} is quite different and is much bigger. Main problem is that there's no transactionality on the same level as in {{3.X}}. {{3.0}} memtables are flushed and renamed to non-tmp names, readers are returned. We need a bit better granularity, since after we may have to abort all the flushed sstables if 2i failed. I've changed it a bit in {{3.x}} fashion, although since we flush to just one sstable, I thought that extracting {{txn}} to the top level will not give us anything.
Both patches introduce the second latch. I'm usually not the biggest fan of two threads that have to wait for one another, but here the ordering is an issue. Problem is that post-flush executor is single-threaded (for ordering), and flush executor is multi-threaded, so we can't return future backed with that multi-threaded executor as it will break order. On the other hand, if we move 2i flush to flush executor, we'll have to sequentially wait for 2i, then all memtables. Current approach allows to keep these actions parallel.
We only need to synchronise the non-cf 2i flush with memtable holding data for current cf. All the cf-index memtables will be in sync with data one anyways since they're combined in the transaction.
|[3.X|https://github.com/ifesdjeen/cassandra/tree/12956-3.X]|[utest|https://cassci.datastax.com/view/Dev/view/ifesdjeen/job/ifesdjeen-12956-3.X-testall/]|[dtest|https://cassci.datastax.com/view/Dev/view/ifesdjeen/job/ifesdjeen-12956-3.X-dtest/]|
|[3.0|https://github.com/ifesdjeen/cassandra/tree/12956-3.0-v2]|[utest|https://cassci.datastax.com/view/Dev/view/ifesdjeen/job/ifesdjeen-12956-3.0-v2-testall/]|[dtest|https://cassci.datastax.com/view/Dev/view/ifesdjeen/job/ifesdjeen-12956-3.0-v2-dtest/]|
|[trunk|https://github.com/ifesdjeen/cassandra/tree/12956-trunk]|[utest|https://cassci.datastax.com/view/Dev/view/ifesdjeen/job/ifesdjeen-12956-trunk-testall/]|[dtest|https://cassci.datastax.com/view/Dev/view/ifesdjeen/job/ifesdjeen-12956-trunk-dtest/]|
was (Author: ifesdjeen):
Patch for {{3.0}} is quite different and is much bigger. Main problem is that there's no transactionality on the same level as in {{3.X}}. {{3.0}} memtables are flushed and renamed to non-tmp names, readers are returned. We need a bit better granularity, since after we may have to abort all the flushed sstables if 2i failed. I've changed it a bit in {{3.x}} fashion, although since we flush to just one sstable, I thought that extracting {{txn}} to the top level will not give us anything.
Both patches introduce the second latch. I'm usually not the biggest fan of two threads that have to wait for one another, but here the ordering is an issue. Problem is that post-flush executor is single-threaded (for ordering), and flush executor is multi-threaded, so we can't return future backed with that multi-threaded executor as it will break order. On the other hand, if we move 2i flush to flush executor, we'll have to sequentially wait for 2i, then all memtables. Current approach allows to keep these actions parallel.
We only need to synchronise the non-cf 2i flush with memtable holding data for current cf. All the cf-index memtables will be in sync with data one anyways since they're combined in the transaction.
|[3.X|https://github.com/ifesdjeen/cassandra/tree/12956-3.X]|[utest|https://cassci.datastax.com/view/Dev/view/ifesdjeen/job/ifesdjeen-12956-3.X-testall/]|[dtest|https://cassci.datastax.com/view/Dev/view/ifesdjeen/job/ifesdjeen-12956-3.X-dtest/]|
|[3.0|https://github.com/ifesdjeen/cassandra/tree/12956-3.0]|[utest|https://cassci.datastax.com/view/Dev/view/ifesdjeen/job/ifesdjeen-12956-3.0-testall/]|[dtest|https://cassci.datastax.com/view/Dev/view/ifesdjeen/job/ifesdjeen-12956-3.0-dtest/]|
|[trunk|https://github.com/ifesdjeen/cassandra/tree/12956-trunk]|[utest|https://cassci.datastax.com/view/Dev/view/ifesdjeen/job/ifesdjeen-12956-trunk-testall/]|[dtest|https://cassci.datastax.com/view/Dev/view/ifesdjeen/job/ifesdjeen-12956-trunk-dtest/]|
> CL is not replayed on custom 2i exception
> -----------------------------------------
>
> Key: CASSANDRA-12956
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12956
> Project: Cassandra
> Issue Type: Bug
> Reporter: Alex Petrov
> Assignee: Alex Petrov
> Priority: Critical
>
> If during the node shutdown / drain the custom (non-cf) 2i throws an exception, CommitLog will get correctly preserved (segments won't get discarded because segment tracking is correct).
> However, when it gets replayed on node startup, we're making a decision whether or not to replay the commit log. CL segment starts getting replayed, since there are non-discarded segments and during this process we're checking whether there every [individual mutation|https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/db/commitlog/CommitLogReplayer.java#L215] in commit log is already committed or no. Information about the sstables is taken from [live sstables on disk|https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/db/commitlog/CommitLogReplayer.java#L250-L256].
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