https://jira.opendaylight.org This file is an XML representation of an issue en-us 8.20.10 820010 22-06-2022 https://jira.opendaylight.org/browse/YANGTOOLS-1537 yangtools <p>We have observed the following:</p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre>2023-08-31T22:31:51,428 | WARN | opendaylight-cluster-data-shard-dispatcher-29 | ShardDataTree | 210 - org.opendaylight.controller.sal-distributed-datastore - 8.0.1 | member-1-shard-topology-operational: Unexpected failure in validation phase java.util.ConcurrentModificationException: null at java.util.HashMap$HashIterator.nextNode(HashMap.java:1597) ~[?:?] at java.util.HashMap$ValueIterator.next(HashMap.java:1625) ~[?:?] at org.opendaylight.yangtools.yang.data.tree.impl.AbstractNodeContainerModificationStrategy.checkChildPreconditions(AbstractNodeContainerModificationStrategy.java:409) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.AbstractNodeContainerModificationStrategy.checkMergeApplicable(AbstractNodeContainerModificationStrategy.java:396) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.SchemaAwareApplyOperation.checkApplicable(SchemaAwareApplyOperation.java:111) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.AbstractNodeContainerModificationStrategy.checkChildPreconditions(AbstractNodeContainerModificationStrategy.java:415) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.AbstractNodeContainerModificationStrategy.checkMergeApplicable(AbstractNodeContainerModificationStrategy.java:396) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.SchemaAwareApplyOperation.checkApplicable(SchemaAwareApplyOperation.java:111) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.AbstractNodeContainerModificationStrategy.checkChildPreconditions(AbstractNodeContainerModificationStrategy.java:415) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.AbstractNodeContainerModificationStrategy.checkMergeApplicable(AbstractNodeContainerModificationStrategy.java:396) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.SchemaAwareApplyOperation.checkApplicable(SchemaAwareApplyOperation.java:111) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.AbstractNodeContainerModificationStrategy.checkChildPreconditions(AbstractNodeContainerModificationStrategy.java:415) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.AbstractNodeContainerModificationStrategy.checkMergeApplicable(AbstractNodeContainerModificationStrategy.java:396) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.SchemaAwareApplyOperation.checkApplicable(SchemaAwareApplyOperation.java:111) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.AbstractNodeContainerModificationStrategy.checkChildPreconditions(AbstractNodeContainerModificationStrategy.java:415) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.AbstractNodeContainerModificationStrategy.checkMergeApplicable(AbstractNodeContainerModificationStrategy.java:396) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.SchemaAwareApplyOperation.checkApplicable(SchemaAwareApplyOperation.java:111) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.AbstractNodeContainerModificationStrategy.checkChildPreconditions(AbstractNodeContainerModificationStrategy.java:415) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.AbstractNodeContainerModificationStrategy.checkTouchApplicable(AbstractNodeContainerModificationStrategy.java:374) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.SchemaAwareApplyOperation.checkApplicable(SchemaAwareApplyOperation.java:109) ~[bundleFile:?] at org.opendaylight.yangtools.yang.data.tree.impl.AbstractDataTreeTip.validate(AbstractDataTreeTip.java:37) ~[bundleFile:?] </pre> </div></div> YANGTOOLS-1537

CME in AbstractNodeContainerModificationStrategy.checkChildPreconditions()

Bug Medium Resolved Done Robert Varga Robert Varga Mon, 4 Sep 2023 20:18:51 +0000 Wed, 6 Sep 2023 09:49:49 +0000 Wed, 6 Sep 2023 09:49:49 +0000 4.0.15 5.0.10 6.0.12 7.0.18 8.0.10 9.0.8 11.0.1 10.0.9 9.0.9 10.0.10 11.0.2 data-impl 0 1 <p>I have not found a codepath which would modify the maps in this codepath, but we have cross-thread interactions here. What I think is happening is that:</p> <ol> <li>since <a href="https://jira.opendaylight.org/browse/YANGTOOLS-1025" title="DataTreeModification does not require volatile seals" class="issue-link" data-issue-key="YANGTOOLS-1025"><del>YANGTOOLS-1025</del></a>, the sequencing in AbstractDataTreeTip.validate() does not do a full volatile read, only an acquire fence (via InMemoryDataTreeModification.isSealed())</li> <li>HashMap's modCount field is using plain stores</li> <li>InMemoryDataTreeModification.ready() issues only a full volatile fence at its beginning</li> <li>therefore all modCount end up not being visible after ready() completes</li> <li>therefore the iterator does <b>NOT</b> see them when it starts, but at some point during execution they do filter in, causing the CME</li> </ol> <p>At the end of the day, what is saving us most of the time is:</p> <ol> <li>the fact that weird modifications do not usually happen</li> <li>the fact that users usually synchronize datastore access themselves, which acts as a fence</li> </ol> Blocks YANGTOOLS-1539 Issue split NETCONF-1146 Relates YANGTOOLS-1025 Development Rank 0|i046ef: