Hrushikesh Mahapatro ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=6097b6b... ) *created* an issue Hibernate ORM ( https://hibernate.atlassian.net/browse/HHH?atlOrigin=eyJpIjoiMjhiOWE4OWQ2... ) / Bug ( https://hibernate.atlassian.net/browse/HHH-16446?atlOrigin=eyJpIjoiMjhiOW... ) HHH-16446 ( https://hibernate.atlassian.net/browse/HHH-16446?atlOrigin=eyJpIjoiMjhiOW... ) org.hibernate.engine.spi.EntityKey consumes a lot of memory ( https://hibernate.atlassian.net/browse/HHH-16446?atlOrigin=eyJpIjoiMjhiOW... ) Issue Type: Bug Affects Versions: 6.2.0 Assignee: Unassigned Components: hibernate-core, hibernate-orm-modules Created: 06/Apr/2023 08:11 AM Environment: Spring boot 3.0.5 Hibernate 6.2.0 Spring Data JPA 3.x Labels: api core Priority: Blocker Reporter: Hrushikesh Mahapatro ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=6097b6b... ) 1 We have just migrated our application to Springboot 3.x, Spring Data JPA 3.1.x & Hibernate 6.1.7 Final. Immediately we observed heap memory spike as we deployed same code without any significant changes. Context: We're trying to fetch a stream of objects from SQL db, and write straight onto a csv file in azure blob storage. As data volume is large 13+GB, we're setting few query hints to fetch 500 objects at a time, disable cacheing also read committed. We're flushing/Clearing both OpenCSV writer and entity manager every 1500 records. This was working all good, until we did this migration. Few code snippets & Profiler Analysis @Transactional(readOnly = true, isolation = Isolation.READ_COMMITTED) public void generateFile() { try (Stream<MyEntity> supplier = myRepo.getDataStream()) { writeOntoFile(ApplicationConstants.REPORT_DIRECTORY, supplier); } catch (IOException ex) { log.error("Error occurred while generating file", ex); } } private <T extends HasId<?>> void writeOntoFile(final String reportDirectory, Stream<T> dataStreamSupplier) throws IOException { final String blobName = blobName(reportDirectory); try (ICSVWriter writer = blobStorageService.getCsvWriterBlobOutputStream(storageContainer, blobName)) { log.info("Writing to {} using beantoCsv mapping", reportDirectory); StatefulBeanToCsv<T> beanToCsv = new StatefulBeanToCsvBuilder<T>(writer).build(); final int[] flushCounter = new int[1]; dataStreamSupplier.forEach(dataRecord -> { writeCSV(reportDirectory, dataRecord, beanToCsv); flushCounter[0]++; if (flushCounter[0] % CLEAR_INTERVAL == 0) { entityManager.clear(); entityManagerFactory.getCache().evict(MyEntity.class); try { writer.flush(); } catch (IOException ioe) { log.error("Unable to flush the writing stream"); throw new RuntimeException(ioe); } } }); log.info("Data written in With Azure Blob file {}", blobName); } catch (RuntimeException re) { log.error("Error occurred while processing report {}", reportDirectory, re); throw re; } Repository Class @Query("select e from MyEntity e JOIN FETCH e.uuid JOIN FETCH e.sourceTable") @QueryHints(value = { @QueryHint(name = HINT_FETCH_SIZE, value = ApplicationConstants.DATA_FETCH_SIZE), @QueryHint(name = HINT_CACHEABLE, value = "false"), @QueryHint(name = HINT_READONLY, value = "true") }) Stream<MyEntity> getDataStream(); Profiler Log:  I tried few things such as entityManagerFactory.getCache.evictAll() seems doesn't work. We're looking to clear these EntityKey objects from Heap. We tried pagination but it's too slow to export such a large volume data. ( https://hibernate.atlassian.net/browse/HHH-16446#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-16446#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#100221- sha1:8f8083a )