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From "Krzysztof Styrc (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-8583) Check for Thread.start()
Date Mon, 19 Jan 2015 23:23:34 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-8583?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14283169#comment-14283169
] 

Krzysztof Styrc commented on CASSANDRA-8583:
--------------------------------------------

Hi,

I've looked through the code under given references. Points 1) 2) and 5) are easily replaceable
with a thread-pool indeed. With 4) and 6) we only have to implement ThreadFactory to provide
backwards-compatible thread names. With 3) it gets even more cumbersome, as we have at least
two extending classes from MessageHandler. It seems not to easy to use one thread-pool and
provide backwards-compatible thread names (imagine IncomingMessageHandler being scheduled
to thread with name STREAM-OUT-XXX).

I guess backwards-compatible thread names are desired, don't they?




> Check for Thread.start()
> ------------------------
>
>                 Key: CASSANDRA-8583
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8583
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Robert Stupp
>            Priority: Minor
>
> Old classes sometimes still use 
> {noformat}
>   new Thread(...).start()
> {noformat}
> which might be costly.
> This ticket's about to find and possibly fix such code.
> Locations in code worth to investigate (IMO). This list is not prioritized - it's just
the order I've found "Thread.start()"
> # {{org.apache.cassandra.streaming.compress.CompressedInputStream#CompressedInputStream}}
creates one thread per input stream to decompress in a separate thread. If necessary, should
be easily replaceable with a thread-pool
> # {{org.apache.cassandra.io.sstable.SSTableSimpleUnsortedWriter#SSTableSimpleUnsortedWriter(java.io.File,
org.apache.cassandra.config.CFMetaData, org.apache.cassandra.dht.IPartitioner, long)}} creates
one thread per write. If necessary, should be easily replaceable with a thread-pool
> # {{org.apache.cassandra.streaming.ConnectionHandler.MessageHandler#start}} creates one
thread. If necessary, should be easily replaceable with a thread-pool.
> # {{org.apache.cassandra.net.OutboundTcpConnection#handshakeVersion}} creates one thread
just to implement a timeout. Not sure why not just using {{Socket.setSoTimeout}}
> # {{org.apache.cassandra.service.StorageService#forceRepairAsync(java.lang.String, org.apache.cassandra.repair.messages.RepairOption)}}
creates one thread per repair. Not sure whether it's worth to investigate this one, since
repairs are "long running" operations
> # {{org.apache.cassandra.db.index.SecondaryIndex#buildIndexAsync}} creates a thread.
Not sure whether it's worth to investigate this one.
> Beside these, there are threads used in {{MessagingService}} and for streaming (blocking
I/O model). These could be changed by using non-blocking I/O - but that's a much bigger task
with much higher risks.



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