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https://issues.apache.org/jira/browse/SLING-10371?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17343808#comment-17343808
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Joerg Hoh commented on SLING-10371:
-----------------------------------
The
[javadoc|https://docs.oracle.com/javase/8/docs/api/java/util/Map.html#computeIfAbsent-K-java.util.function.Function-]
(Java8) does not make any assumption about concurrency, but that's different
with [java
11|https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/concurrent/ConcurrentHashMap.html#computeIfAbsent(K,java.util.function.Function)]:
_The entire method invocation is performed atomically, so the function is
applied at most once per key. Some attempted update operations on this map by
other threads may be blocked while computation is in progress, so the
computation should be short and simple, and {color:red}must not attempt to
update any other mappings of this map{color}._
I don't think that concurrency (as in parallel access via multiple threads) is
a big concern, as most classes inheriting from {{SlingAdaptable}} are not
thread-safe anyway.
> SlingAdaptable: ConcurrentModificationException on nested adaptTo() calls
> -------------------------------------------------------------------------
>
> Key: SLING-10371
> URL: https://issues.apache.org/jira/browse/SLING-10371
> Project: Sling
> Issue Type: Task
> Components: API
> Affects Versions: API 2.23.4
> Reporter: Joerg Hoh
> Assignee: Joerg Hoh
> Priority: Major
> Fix For: API 2.23.6
>
> Time Spent: 1h 20m
> Remaining Estimate: 0h
>
> I introduced a regression with SLING-10327, that nested adaptTo() calls on
> the same adaptable throw a ConcurrentModificationException.
> {noformat}
> java.util.ConcurrentModificationException
> at java.base/java.util.HashMap.computeIfAbsent(HashMap.java:1134)
> at
> org.apache.sling.api.adapter.SlingAdaptable.adaptTo(SlingAdaptable.java:104)
> at
> org.apache.sling.resourceresolver.impl.ResourceResolverImpl.adaptTo(ResourceResolverImpl.java:636)
> {noformat}
> Reverting
> https://github.com/apache/sling-org-apache-sling-api/commit/eeb8f84f92a2f1bbfad236ba9dca9c15c2e837f3
>
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