[jira] [Commented] (OFBIZ-6747) Replace ConcurrentLinkedHashMap by Caffeine

[Nicolas Malin (Jira)]

    [ https://issues.apache.org/jira/browse/OFBIZ-6747?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16508717#comment-16508717 ]

Taher Alkhateeb commented on OFBIZ-6747:
----------------------------------------

Thank you Ben, this is indeed quite informative.

So I see two places where the specific implementation is used explicitly in the code:
 * org.apache.ofbiz.service.ServiceDispatcher:
{code:java}
protected static final Map<RunningService, ServiceDispatcher> runLog = new ConcurrentLinkedHashMap.Builder<RunningService, ServiceDispatcher>().maximumWeightedCapacity(lruLogSize).build();
{code}

 * org.apache.ofbiz.base.util.cache.UtilCache
{code:java}
    public void setMaxInMemory(int newInMemory) {
        this.maxInMemory = newInMemory;
        Map<Object, CacheLine<V>> oldmap = this.memoryTable;

        if (newInMemory > 0) {
            if (this.memoryTable instanceof ConcurrentLinkedHashMap<?, ?>) {
                ((ConcurrentLinkedHashMap<?, ?>) this.memoryTable).setCapacity(newInMemory);
                return;
            }
            this.memoryTable =new Builder<Object, CacheLine<V>>()
                    .maximumWeightedCapacity(newInMemory)
                    .build();
        } else {
            this.memoryTable = new ConcurrentHashMap<>();
        }

        this.memoryTable.putAll(oldmap);
    }
{code}

So the question on my mind is, what is the simplest way to switch out. I guess we need to replace the builder logic along with the other specific methods that are being called.

> Replace ConcurrentLinkedHashMap by Caffeine
> -------------------------------------------
>
>                 Key: OFBIZ-6747
>                 URL: https://issues.apache.org/jira/browse/OFBIZ-6747
>             Project: OFBiz
>          Issue Type: Task
>            Reporter: Ben Manes
>            Assignee: Jacques Le Roux
>            Priority: Minor
>
> Similar to OFBIZ-3779, please consider upgrading the library used by [UtilCache|https://github.com/apache/ofbiz/blob/trunk/framework/base/src/org/ofbiz/base/util/cache/UtilCache.java] (v1.2). The current version is 1.4.2 and is the last major release planned.
> The preferable alternative would be to upgrade to [Caffeine|https://github.com/ben-manes/caffeine]. This is a Java 8 rewrite based on what I've learned since developing CLHM and Guava's cache. As expected it provides [superior performance|https://github.com/ben-manes/caffeine/wiki/Benchmarks]. It also provides a [near optimal|https://github.com/ben-manes/caffeine/wiki/Efficiency] eviction policy.

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