assertTrue(source.get("field1").toString().startsWith("test"));
                    valueSet.add(source.get("field1").toString());
                    count.getAndIncrement();
                }
            });
        }

        for (Thread th : threads) {
            th.start();
        }
        for (Thread th : threads) {
            th.join();
        }

            @Override
            public QueryLog read() {
                if (count.get() >= queryLogs.length) {
                    return null;
                }
                return new QueryLog(queryLogs[count.getAndIncrement()], null);
            }

            @Override
            public void close() {
                // ignore
            }
        };