GitHub user NicoK opened a pull request:
https://github.com/apache/flink/pull/4445
[FLINK-7310][core] always use the HybridMemorySegment
## What is the purpose of the change
Since we'd like to use our own off-heap buffers for network communication,
we cannot use `HeapMemorySegment` anymore and need to rely on
`HybridMemorySegment`. We thus drop any code that loads the `HeapMemorySegment`
(it is still available if needed) in favour of the `HybridMemorySegment` which
is able to work on both heap and off-heap memory.
For the performance penalty of this change compared to using
`HeapMemorySegment` alone, see this interesting blob article (from 2015):
https://flink.apache.org/news/2015/09/16/off-heap-memory.html
## Brief change log
- drop any use of the `HeapMemorySegment` (however, for now, keep the
class and its factory)
- integrate `HybridMemorySegmentFactory` into `MemorySegmentFactory`
(with hard-coded use of `HybridMemorySegment`)
## Verifying this change
This change is already covered by existing tests, such as: memory-backend
specific tests under `flink/core/memory` or actually all other tests running
programs on Flink. Actually, the `HybridMemorySegment` was not really tested
much in integration tests so far because most tests used on-heap memory and
thus `HeapMemorySegment`. Since we now only use `HybridMemorySegment`, we do
add a lot of tests for this.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): (no)
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: (no)
- The serializers: (no)
- The runtime per-record code paths (performance sensitive): (yes)
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Yarn/Mesos, ZooKeeper: (no)
## Documentation
- Does this pull request introduce a new feature? (no)
- If yes, how is the feature documented? (not applicable)
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/NicoK/flink flink-7310
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/4445.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 #4445
----
commit c62e793712effbfb53ea6442b5d714a68081f7ec
Author: Nico Kruber <n...@data-artisans.com>
Date: 2017-07-31T10:06:14Z
[hotfix] fix some typos
commit d3c4e231a96b6ae133576a74646294749ab3809a
Author: Nico Kruber <n...@data-artisans.com>
Date: 2017-07-31T12:18:42Z
[FLINK-7310][core] always use the HybridMemorySegment
Since we'd like to use our own off-heap buffers for network communication,
we
cannot use HeapMemorySegment anymore and need to rely on
HybridMemorySegment.
We thus drop any code that loads the HeapMemorySegment (it is still
available
if needed) in favour of the HybridMemorySegment which is able to work on
both
heap and off-heap memory.
For the performance penalty of this change compared to using
HeapMemorySegment
alone, see this interesting blob article (from 2015):
https://flink.apache.org/news/2015/09/16/off-heap-memory.html
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