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From "Thomas Jungblut (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HAMA-559) Add a spilling message queue
Date Sat, 27 Oct 2012 21:49:12 GMT

    [ https://issues.apache.org/jira/browse/HAMA-559?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13485514#comment-13485514

Thomas Jungblut commented on HAMA-559:

Okay the mutiple pools were used for multiple buffers, obviously. So no problem.

I used 4g sequential write:
DiskList: Written 4096mb in 34174ms! That is 119,86mb/s!
SpillingBuffer: Written 4096mb in 62065ms! That is 66mb/s!

So what I ask myself: 
Why is the bytebuffer (although mapped to memory) performing so worse? Exactly 2x slower than
normal FileOutputStream.

That said, I'm using java7, so there maybe improvements done that aren't in JDK6.
> Add a spilling message queue
> ----------------------------
>                 Key: HAMA-559
>                 URL: https://issues.apache.org/jira/browse/HAMA-559
>             Project: Hama
>          Issue Type: Sub-task
>          Components: bsp core
>    Affects Versions: 0.5.0
>            Reporter: Thomas Jungblut
>            Assignee: Suraj Menon
>            Priority: Minor
>             Fix For: 0.7.0
>         Attachments: HAMA-559.patch-v1, spilling_buffer_cpu_usage_text_write.png, SpillingBufferProfile-2012-10-27.snapshot,
spilling_buffer_profile_cpu_graph_test_write.png, spilling_buffer_profile_cpugraph_writeUTF.png,
spillingbuffer_profile_cpu_writeUTF.png, spilling_buffer_profile_LOCK.JPG, spilling_buffer_profile_timesplit_text_write.png,
> After HAMA-521 is done, we can add a spilling queue which just holds the messages in
RAM that fit into the heap space. The rest can be flushed to disk.
> We may call this a HybridQueue or something like that.
> The benefits should be that we don't have to flush to disk so often and get faster. However
we may have more GC so it is always overall faster.
> The requirements for this queue also include:
> - The message object once written to the queue (after returning from the write call)
could be modified, but the changes should not be reflected in the messages stored in the queue.
> - For now let's implement a queue that does not support concurrent reading and writing.
This feature is needed when we implement asynchronous communication.

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