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https://issues.apache.org/jira/browse/BOOKKEEPER-964?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15630534#comment-15630534
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ASF GitHub Bot commented on BOOKKEEPER-964:
-------------------------------------------
GitHub user merlimat opened a pull request:
https://github.com/apache/bookkeeper/pull/72
BOOKKEEPER-964: Add concurrent maps and sets for primitive types
In BookKeeper there are many instances of maps and sets that use ledger id
and entry ids as keys or values. JDK concurrent collections have the
overhead
of boxing all the primitive values into objects (eg: long --> Long) that
would
need to be allocated from the heap. In addition to that, JDK map
implementations
are closed hash tables and they will require at least one more allocation
to hold
the linked-list/tree node.
There are already available libraries that offer primitive collections with
zero-allocation, but none of these support concurrent maps/sets.
We have added a handful of specializations, all based on the same
implementation
idea. We have a hash table which is broken down into multiple sections. Each
sections, on its own, is an open hash table with linear probing, protected
by
a stamped lock.
All insertions, lookups and iterations on these collections are allocation
free.
```
ConcurrentLongHashMap: Map<long, Object>
ConcurrentLongHashSet: Set<long>
ConcurrentLongLongHashMap: Map<long, long>
ConcurrentLongLongPairHashMap: Map< Pair<long, long>, Pair<long, long> >
ConcurrentOpenHashMap: Map<Object, Object>
ConcurrentOpenHashSet: Set<Object>
```
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/merlimat/bookkeeper bk-collections
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/bookkeeper/pull/72.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 #72
----
commit 7e315d934d15beef2f1ce8930f223489636a09df
Author: Matteo Merli <[email protected]>
Date: 2016-11-02T21:08:48Z
BOOKKEEPER-964: Add concurrent maps and sets for primitive types
----
> Add concurrent maps and sets for primitive types
> ------------------------------------------------
>
> Key: BOOKKEEPER-964
> URL: https://issues.apache.org/jira/browse/BOOKKEEPER-964
> Project: Bookkeeper
> Issue Type: Improvement
> Reporter: Matteo Merli
> Assignee: Matteo Merli
> Fix For: 4.5.0
>
>
> In BookKeeper there are many instances of maps and sets that use ledger id
> and entry ids as keys or values. JDK concurrent collections have the overhead
> of boxing all the primitive values into objects (eg: long --> Long) that would
> need to be allocated from the heap. In addition to that, JDK map
> implementations
> are closed hash tables and they will require at least one more allocation to
> hold
> the linked-list/tree node.
> There are already available libraries that offer primitive collections with
> zero-allocation, but none of these support concurrent maps/sets.
> We have added a handful of specializations, all based on the same
> implementation
> idea. We have a hash table which is broken down into multiple sections. Each
> sections, on its own, is an open hash table with linear probing, protected by
> a stamped lock.
> All insertions, lookups and iterations on these collections are allocation
> free.
> {noformat}
> ConcurrentLongHashMap: Map<long, Object>
> ConcurrentLongHashSet: Set<long>
> ConcurrentLongLongHashMap: Map<long, long>
> ConcurrentLongLongPairHashMap: Map< Pair<long, long>, Pair<long, long> >
> ConcurrentOpenHashMap: Map<Object, Object>
> ConcurrentOpenHashSet: Set<Object>
> {noformat}
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