accumulo-notifications mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Billie Rinaldi (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (ACCUMULO-1833) MultiTableBatchWriterImpl.getBatchWriter() is not performant for multiple threads
Date Thu, 31 Oct 2013 20:03:18 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-1833?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13810635#comment-13810635
] 

Billie Rinaldi edited comment on ACCUMULO-1833 at 10/31/13 8:02 PM:
--------------------------------------------------------------------

It would be better if it didn't have to do the table name to id lookup each time, and that
would be avoided if the app had its own cache based on name.  We could consider adding a new
method that gets based on the id rather than the name, but I don't think we should change
the existing method to use the id.

In any case it seems like there might be a problem with the ZooCache that we should fix.


was (Author: billie.rinaldi):
It would be better if it didn't have to do the table name to id lookup each time, and that
would be avoided if the app had its own cache based on name.  We could consider adding a new
method that gets based on the id rather than the name, but I don't think we should change
the existing method to use the id.

In any case it seems like might be a problem with the ZooCache that we should fix.

> MultiTableBatchWriterImpl.getBatchWriter() is not performant for multiple threads
> ---------------------------------------------------------------------------------
>
>                 Key: ACCUMULO-1833
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-1833
>             Project: Accumulo
>          Issue Type: Improvement
>    Affects Versions: 1.5.0, 1.6.0
>            Reporter: Chris McCubbin
>
> This issue comes from profiling our application. We have a MultiTableBatchWriter created
by normal means. I am attempting to write to it with multiple threads by doing things like
the following:
> {code}
> batchWriter.getBatchWriter(table).addMutations(mutations);
> {code}
> In my test with 4 threads writing to one table, this call is quite inefficient and results
in a large performance degradation over a single BatchWriter.
> I believe the culprit is the fact that the call is synchronized. Also there is the possibility
that the zookeeper call to Tables.getTableState on every call is negatively affecting performance:
> {code}
>   @Override
>   public synchronized BatchWriter getBatchWriter(String tableName) throws AccumuloException,
AccumuloSecurityException, TableNotFoundException {
>     ArgumentChecker.notNull(tableName);
>     String tableId = Tables.getNameToIdMap(instance).get(tableName);
>     if (tableId == null)
>       throw new TableNotFoundException(tableId, tableName, null);
>     
>     if (Tables.getTableState(instance, tableId) == TableState.OFFLINE)
>       throw new TableOfflineException(instance, tableId);
>     
>     BatchWriter tbw = tableWriters.get(tableId);
>     if (tbw == null) {
>       tbw = new TableBatchWriter(tableId);
>       tableWriters.put(tableId, tbw);
>     }
>     return tbw;
>   }
> {code}
> I recommend moving the synchronized block to happen only if the batchwriter is not present,
and also only checking if the table is online at that time:
> {code}
>   @Override
>   public BatchWriter getBatchWriter(String tableName) throws AccumuloException, AccumuloSecurityException,
TableNotFoundException {
>     ArgumentChecker.notNull(tableName);
>     String tableId = Tables.getNameToIdMap(instance).get(tableName);
>     if (tableId == null)
>       throw new TableNotFoundException(tableId, tableName, null);
>     BatchWriter tbw = tableWriters.get(tableId);
>     if (tbw == null) {
>       if (Tables.getTableState(instance, tableId) == TableState.OFFLINE)
>           throw new TableOfflineException(instance, tableId);
>       tbw = new TableBatchWriter(tableId);
>       synchronized(tableWriters){
>           //only create a new table writer if we haven't been beaten to it.
>           if (tableWriters.get(tableId) == null)      
>               tableWriters.put(tableId, tbw);
>       }
>     }
>     return tbw;
>   }
> {code}



--
This message was sent by Atlassian JIRA
(v6.1#6144)

Mime
View raw message