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https://issues.apache.org/jira/browse/HDDS-1512?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Bharat Viswanadham updated HDDS-1512:
-------------------------------------
    Status: Patch Available  (was: Open)

> Implement DoubleBuffer in OzoneManager
> --------------------------------------
>
>                 Key: HDDS-1512
>                 URL: https://issues.apache.org/jira/browse/HDDS-1512
>             Project: Hadoop Distributed Data Store
>          Issue Type: Sub-task
>            Reporter: Bharat Viswanadham
>            Assignee: Bharat Viswanadham
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> This Jira is created to implement DoubleBuffer in OzoneManager to flush 
> transactions to OM DB.
>  
> h2. Flushing Transactions to RocksDB:
> We propose using an implementation similar to the HDFS EditsDoubleBuffer.  We 
> shall flush RocksDB transactions in batches, instead of current way of using 
> rocksdb.put() after every operation. At a given time only one batch will be 
> outstanding for flush while newer transactions are accumulated in memory to 
> be flushed later.
>  
> In DoubleBuffer it will have 2 buffers one is currentBuffer, and the other is 
> readyBuffer. We add entry to current buffer, and we check if another flush 
> call is outstanding. If not, we flush to disk Otherwise we add entries to 
> otherBuffer while sync is happening.
>  
> In this if sync is happening, we shall add new requests to other buffer and 
> when we can sync we use *RocksDB batch commit to sync to disk, instead of 
> rocksdb put.*
>  
> Note: If flush to disk is failed on any OM, we shall terminate the 
> OzoneManager, so that OM DB’s will not diverge. Flush failure should be 
> considered as catastrophic failure.
>  
> Scope of this Jira is to add DoubleBuffer implementation, integrating to 
> current OM will be done in further jira's.
>  



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