[jira] [Updated] (IGNITE-18475) Huge performance drop with enabled sync write per log entry for RAFT logs

["Alexey Scherbakov (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IGNITE-18475?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Alexey Scherbakov updated IGNITE-18475:
---------------------------------------
     Epic Name:   (was: Ignite 3 fsync optimizations)
        Parent: IGNITE-19479
    Issue Type: Sub-task  (was: Epic)

> Huge performance drop with enabled sync write per log entry for RAFT logs
> -------------------------------------------------------------------------
>
>                 Key: IGNITE-18475
>                 URL: https://issues.apache.org/jira/browse/IGNITE-18475
>             Project: Ignite
>          Issue Type: Sub-task
>            Reporter: Kirill Gusakov
>            Assignee: Ivan Bessonov
>            Priority: Major
>              Labels: ignite-3
>          Time Spent: 1h 10m
>  Remaining Estimate: 0h
>
> During the YCSB benchmark runs for ignite-3 beta1 we found out, that we have significant issues with performance for select/insert queries.
> One of the root cause of these issues: write every log entry to rocksdb with enabled sync option (which leads to frequent fsync calls).
> These issues can be reproduced by localised jmh benchmarks [SelectBenchmark|https://github.com/gridgain/apache-ignite-3/blob/4b9de922caa4aef97a5e8e159d5db76a3fc7a3ad/modules/runner/src/test/java/org/apache/ignite/internal/benchmark/SelectBenchmark.java#L39] and [InsertBenchmark|https://github.com/gridgain/apache-ignite-3/blob/4b9de922caa4aef97a5e8e159d5db76a3fc7a3ad/modules/runner/src/test/java/org/apache/ignite/internal/benchmark/InsertBenchmark.java#L29] with RaftOptions.sync=true/false:
>  * jdbc select queries: 115ms vs 4ms
>  * jdbc insert queries: 70ms vs 2.5ms
> (These results received on MacBook Pro (16-inch, 2019) and it looks like macOS has slow fsync command in general, but runs on Ubuntu shows the huge different also (~26 times for insert test). So, your environment can show another, but still huge difference.)
> Why select queries suffers from syncs even more, than inserts, described in https://issues.apache.org/jira/browse/IGNITE-18474.
> Possible solutions for the issue:
>  * Doesn't sync every raft record in rocksdb by default, but it can break the raft invariants
>  * Investigate the inner parts of RocksDB (according syscall tracing, not every write with sync produce fsync syscall), maybe another strategies wll be suitable for our cases
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