Inconsistent Owned Hibernate Object - spring-boot

Question

posting for a colleague, we’ve encountered unexpected data fetching behaviour and would like to ask for any ideas on how and why it could be done this way. The problem is that we have managed entities with the same id but in a different state. Unfortunately, it’s not reproducible locally. We can see that behaviour from the AWS-hosted EC2 Intel Instance and are only able to verify it from logs.
Used classes:
class History {
private Enum status;
#OneToMany(mappedBy = HistoryEntry_.HISTORY)
#OrderBy("id ASC")
#BatchSize(size = 10)
private List<HistoryEntry> entries = new LinkedList<>();
}
// binds 2 parts of the system
class HistoryEntry {
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "history_id", updatable = false, nullable = false)
private History history;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "process_id", updatable = false, nullable = false)
private ProcessInfo processInfo;
}
class ProcessInfo {
#OneToMany(mappedBy = HistoryEntry_.PROCESS_INFO)
// just for deterministic ordering within the transaction
#OrderBy("id ASC")
#BatchSize(size = 10)
private List<HistoryEntry> entries = new LinkedList<>();
}
Initial State
History history1 = new History(Status.PENDING);
ProcessInfo processInfo1 = new ProcessInfo();
ProcessInfo processInfo2 = new ProcessInfo();
HistoryEntry entryA = new HistoryEntry(history, processInfo1);
HistoryEntry entryB = new HistoryEntry(history, processInfo1);
History1 in PENDING status containing a list of [A, B] entries
ProcessInfo1 containing a list of [A, B] entries
ProcessInfo2 without entries
New Entry linking to History1
The execution runs in a single transaction
// returns a list with 2 entries A and B
List<HistoryEntry> entries = historyEntryRepo.findAllByProcessInfoAndNotArchived(processInfo1);
// a set with a single history1. Comparison done by id.
Set<History> histories = entries.stream()
.map(HistoryEntry::getHistory)
.toSet();
// expecting a single element
if(histories.size() > 1){
throw new IllegalStateException();
}
History history1 = histories.iterator().next();
entityManager.lock(history1, LockModeType.OPTIMISTIC_FORCE_INCREMENT);
HistoryEntry entryC = new HistoryEntry();
entryC.setHistory(history1);
history1.getEntries().add(entryC);
history1.status = Status.COMPLETED;
entryC.setProcessInfo(processInfo2);
processInfo2.getEntries().add(entryC);
historyEntryRepo.save(entryC);
Inconsistent Data
Within the same transaction, I want to verify the status of each history entity.
Set<History> histories1 = processInfo1.getEntries().stream()
.map(HistoryEntry::getHistory)
.toSet();
Set<History> histories2 = processInfo2.getEntries().stream()
.map(HistoryEntry::getHistory)
.toSet();
Both return a single result - History1 - with the same id but with a different status field value. This is unexpected, to say the least.
History(id=1, status=PENDING) unexpected
History(id=1, status=COMPLETED)
Reloading for Consistency
It’s “fixed” by doing a fetch from the repo anew.
historyEntryRepo.findAllByProcessInfo(processInfo1).stream()
.map(HistoryEntry::getHistory)
.toSet();
historyEntryRepo.findAllByProcessInfo(processInfo2).stream()
.map(HistoryEntry::getHistory)
.toSet();
Now, the outcome is the same and expected: History(id=1, status=COMPLETED)
Is this some caching or rather cache-invalidation gone wrong?