Hi @Jeffrey_Yemin ,
We had an issue with insufficient precision when passing the date object to the driver. This does not fully explain the error with an actual time difference described above. But it seems, there were 2 parallel threads that set the new value simultaneously despite the fully stopping breakpoints. I’ll try to verify that once more though.
I set up a database with a collection “testobject” holding only this document:
{
"_id" : ObjectId("619fa87fa0e5600fb486442f"),
"id" : "1",
"lastSync" : ISODate("2021-11-25T15:41:56.000Z")
}
The error was reproducible with the following code using Java 16 and the mongodb driver version 4.3.4:
package main;
import com.mongodb.BasicDBObject;
import com.mongodb.client.MongoClient;
import com.mongodb.client.MongoClients;
import com.mongodb.client.model.UpdateOptions;
import org.bson.Document;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.util.Date;
public class Main {
public static void main(String[] args) {
MongoClient client = MongoClients.create();
for (int i = 0; i < 3; i++) {
int finalI = i;
new Thread(() -> {
BasicDBObject filterObject = new BasicDBObject("id", "1");
Document updateObject = new Document();
Date date = Date.from(LocalDateTime.now().withNano(0).atZone(ZoneId.systemDefault()).toInstant());
updateObject.put("$set", new BasicDBObject("lastSync", date));
UpdateOptions updateOptions = new UpdateOptions().upsert(false);
System.out.println("thread " + finalI + ", update: " + updateObject.toJson());
long updatedDocuments = client.getDatabase("local-mongo-test").getCollection("testobject").updateOne(filterObject, updateObject, updateOptions).getModifiedCount();
if (updatedDocuments == 0) {
throw new IllegalStateException("update performed, but not reported");
}
}).start();
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
Executing this produced the following output:
thread 0, update: {"$set": {"lastSync": {"$date": "2021-11-25T17:22:44Z"}}}
thread 1, update: {"$set": {"lastSync": {"$date": "2021-11-25T17:22:44Z"}}}
Exception in thread "Thread-1" java.lang.IllegalStateException: update performed, but not reported
at main.Main.lambda$main$0(Main.java:32)
at java.base/java.lang.Thread.run(Thread.java:831)
thread 2, update: {"$set": {"lastSync": {"$date": "2021-11-25T17:22:45Z"}}}
While building this example, I noticed that the initialized Date object did not contain milliseconds. We need to ignore the nanoseconds provided by LocalDateTime in other parts of the application, so we dropped them using .withNano(0). Meaning that updates performed within the same second would not require a change in the database.
When initializing the Date as follows, the database updates work as expected and no Exception is thrown in the example above:
Date date = new Date(LocalDateTime.now().atZone(ZoneId.systemDefault()).toInstant().toEpochMilli());
