[ https://issues.jboss.org/browse/WFCORE-3948?page=com.atlassian.jira.plugi... ] Brian Stansberry commented on WFCORE-3948: ------------------------------------------ I fear making AttachmentList thread safe is something of a sweep-the-problem-under-the-rug approach, as the ConcurrentModificationException is telling us something useful -- we've got a reader executing concurrent with a writer. Presumably what the writer is doing is relevant, so preventing the reader going at the same time doesn't mean the readers see the full set of information. Any readers in a later Phase than writers should be fine; it's the readers in the same phase that are at risk of incorrect reads. The subdeployments execute their DUPs for a phase concurrently. So Scott's point re "Could it help to get the "topLevelDeployment.addToAttachmentList(Attachments.ADDITIONAL_MODULES, module)" call to happen before the subdeployers are called?" is on target. -- This message was sent by Atlassian Jira (v7.13.8#713008)