GitHub user franz1981 opened a pull request:
https://github.com/apache/activemq-artemis/pull/981
ARTEMIS-906 Memory Mapped JournalType
It adds the memory mapped journal file as a viable option in addition to
AIO and NIO Journal types.
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](https://github.com/franz1981/activemq-artemis/blob/mmap_fix/artemis-journal/src/test/java/org/apache/activemq/artemis/core/io/JournalTptBenchmark.java)
) 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 support.
```text
----------------------
------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](https://github.com/franz1981/activemq-artemis/blob/mmap_fix/artemis-journal/src/test/java/org/apache/activemq/artemis/core/io/SequentialFileTptBenchmark.java)
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.
```text
-----------------------
----SEQUENTIAL FILE----
-----------------------
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
```
Configuration:
Linux matrix 4.9.3-200.fc25.x86_64 SMP (performance mode)
Intel® Core⢠i7-6820HQ CPU @ 2.70GHz à 8 (Hyper Threading disabled)
OS's PAGESIZE = 4096 bytes
SSD: SAMSUNG MZ7LN512HMJP-000L7
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/franz1981/activemq-artemis mmap_fix
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/activemq-artemis/pull/981.patch
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 <[email protected]>
Date: 2016-12-16T10:12:22Z
ARTEMIS-906 Memory Mapped JournalType
----
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