try to createStatementIterator once more after exception before giving up

Author: hmottestad

core/sail/lmdb/src/main/java/org/eclipse/rdf4j/sail/lmdb/LmdbSailStore.java

@@ -920,7 +920,14 @@ public CloseableIteration<? extends Statement> getStatements(Resource subj, IRI
 			try {
 				return createStatementIterator(txn, subj, pred, obj, explicit, contexts);
 			} catch (IOException e) {
-				throw new SailException("Unable to get statements", e);
+				try {
+					logger.warn("Failed to get statements, retrying", e);
+					// try once more before giving up
+					Thread.yield();
+					return createStatementIterator(txn, subj, pred, obj, explicit, contexts);
+				} catch (IOException e2) {
+					throw new SailException("Unable to get statements", e);
+				}
 			}
 		}
 

core/sail/shacl/src/test/java/org/eclipse/rdf4j/sail/shacl/MultithreadedTest.java

@@ -356,6 +356,9 @@ public void testLotsOfValidationFailuresSnapshot() throws IOException {
 	@Test
 	public void testLotsOfValidationFailuresSerializableValidation() throws IOException {
 		System.out.println("testLotsOfValidationFailuresSerializableValidation");
+		Logger root = (Logger) LoggerFactory.getLogger(ShaclSailBaseConfiguration.class.getName());
+		root.setLevel(Level.ERROR);
+
 		ShaclSail sail = new ShaclSail(getBaseSail());
 
 		sail.setParallelValidation(true);