Sanne Grinovero ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) *updated* an issue Hibernate ORM ( https://hibernate.atlassian.net/browse/HHH?atlOrigin=eyJpIjoiNmY5MTc1YWI0... ) / Improvement ( https://hibernate.atlassian.net/browse/HHH-15651?atlOrigin=eyJpIjoiNmY5MT... ) HHH-15651 ( https://hibernate.atlassian.net/browse/HHH-15651?atlOrigin=eyJpIjoiNmY5MT... ) StatefulPersistenceContext#clear shouldn't need defensive copies for iteration ( https://hibernate.atlassian.net/browse/HHH-15651?atlOrigin=eyJpIjoiNmY5MT... ) Change By: Sanne Grinovero ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) The method {{org.hibernate.engine.internal.EntityEntryContext#reentrantSafeEntityEntries}} is allocating a defensive copy of the data structure for iteration, but this has been shown as not being very efficient in terms of memory allocations. We should explore alternatives, especially as I There ’ ve noticed since ORM 6 s some code that indeed requires this defensive step, but the clear method on StatefulPersistenceContext is now only used by also using it; I’ll be adding a single path: optimised version of the Session#clear() method which is better suited for such operations. Hopefully that simplifies things. ( https://hibernate.atlassian.net/browse/HHH-15651#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-15651#add-comment?atlOrigin=ey... ) Get Jira notifications on your phone! Download the Jira Cloud app for Android ( https://play.google.com/store/apps/details?id=com.atlassian.android.jira.... ) or iOS ( https://itunes.apple.com/app/apple-store/id1006972087?pt=696495&ct=Em... ) This message was sent by Atlassian Jira (v1001.0.0-SNAPSHOT#100210- sha1:a877796 )