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From franz1981 <>
Subject [GitHub] activemq-artemis pull request #981: ARTEMIS-906 Memory Mapped JournalType
Date Tue, 31 Jan 2017 13:20:44 GMT
GitHub user franz1981 opened a pull request:

    ARTEMIS-906 Memory Mapped JournalType

    It adds the memory mapped journal file as a viable option in addition to AIO and NIO Journal
    The implementation is straightforward and pure sync, beside optimisations aimed to reduce
garbage collection pauses.
    There is by design no support on batch writes/flushes (using a TimedBuffer) or async writes
(as AIO): async behaviours must (and will) be provided via external wrappers, leaving the
base implementation simple and single-threaded.
    The benchmark (end to end and [isolated](
) results below shows an advantage in performance of AIO using a default configuration with
full durable semantics and a huge advantage using MAPPED for durable writes with solely process-failure
    ------END TO END------
    messageSize = 100 bytes
    AIO NO DATA SYNC:					925 ops/sec
    MAPPED NO DATA SYNC:					9418 ops/sec
    AIO with DATA SYNC:					710 ops/sec
    MAPPED with DATA SYNC:					670 ops/sec
    [Isolated benchmarks](
on plain SequentialFile implementations show a huge improvement for non durable (process failure
only) writes while for full durable writes performs on par with the AIO version running with
default parameters. 
    It leads to the conclusion that the Journal involves the SequentialFile implementation
in some tasks expecting async behaviours from it and penalizing synchronous ones; it will
require further investigations.
    AIO SequentialFile sync writes no datasync: 		1972 ops/sec
    MAPPED SequentialFile sync writes no datasync:		41293903 ops/sec
    AIO SequentialFile sync writes with datasync: 		1201 ops/sec
    MAPPED SequentialFile sync writes with datasync:	1202 ops/sec
    Linux matrix 4.9.3-200.fc25.x86_64 SMP (performance mode)
    Intel® Core™ i7-6820HQ CPU @ 2.70GHz × 8 (Hyper Threading disabled)
    OS's PAGESIZE = 4096 bytes

You can merge this pull request into a Git repository by running:

    $ git pull mmap_fix

Alternatively you can review and apply these changes as the patch at:

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #981
commit 846acc715492d10b6846406b5d3fff43c0f18a2b
Author: Francesco Nigro <>
Date:   2016-12-16T10:12:22Z

    ARTEMIS-906 Memory Mapped JournalType


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