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From "Suraj Menon (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HAMA-559) Add a spilling message queue
Date Sat, 03 Nov 2012 03:40:11 GMT

    [ https://issues.apache.org/jira/browse/HAMA-559?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13489916#comment-13489916
] 

Suraj Menon commented on HAMA-559:
----------------------------------

Just looked into the code. I did not profile the code, but isn't the GC coming into picture
as the byte buffers are added and removed?

> It is faster than yours, but I still can't hit the throughput limit of my drives. Very
strange, there must be some abstraction layers in Java causing significant overhead...
Could it be because we are not setting cpu affinity for both the threads?

Are these Java 6 or 7 numbers?
                
> 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, spillbench_code.tar.gz, 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, spilling_buffer_profile_writeUTF.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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