Github user wastl commented on a diff in the pull request:
https://github.com/apache/marmotta/pull/15#discussion_r44345877
--- Diff:
libraries/kiwi/kiwi-triplestore/src/main/java/org/apache/marmotta/kiwi/sail/KiWiValueFactory.java
---
@@ -575,13 +577,29 @@ public Statement createStatement(Resource subject,
URI predicate, Value object,
registry.registerKey(cacheKey,
connection.getTransactionId(), result.getId());
} else {
// not found in registry, try loading from database
-
result.setId(connection.getTripleId(ksubject,kpredicate,kobject,kcontext));
+ needsDBLookup = true;
}
+ }
+
+ if(needsDBLookup) {
+
result.setId(connection.getTripleId(ksubject,kpredicate,kobject,kcontext));
+ }
- // triple has no id from registry or database, so we
create one and flag it for reasoning
- if(result.getId() < 0) {
- result.setId(connection.getNextSequence());
- result.setNewTriple(true);
+ // triple has no id from registry or database, so we create
one and flag it for reasoning
+ if(result.getId() < 0) {
+ synchronized (registry) {
+ // It's possible a concurrent thread might have
created this
+ // triple while we were blocked. Check the registry
again.
+ long tripleId = registry.lookupKey(cacheKey);
+
+ if(tripleId >= 0) {
+ // A concurrent thread got in first. Take the one
it created.
+ result.setId(tripleId);
--- End diff --
I guess in this case the call to registerKey below is not needed (it came
from the registry).
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