总之，当文档不属于工作集(不在驻留内存中)时，我们在对现有文档进行并发更新时遇到了这种奇怪的行为。
更多详细信息:
给定一个具有唯一索引的集合，并且在给定现有文档上以 upsert 为 true 运行并发更新(3 个线程)时，1 到 2 个线程会引发以下异常:
Processing failed (Write failed with error code 11000 and error message 'insertDocument :: caused by :: 11000 E11000 duplicate key error index: db1.col1.$key_1 dup key: { : 1008 }'):
根据文档，我希望所有三个更新都会成功，因为我尝试更新的文档已经存在。相反，它看起来像是尝试对少数或全部更新请求进行插入，并且由于唯一索引而很少失败。
对文档重复相同的并发更新不会引发任何异常。此外，在文档上使用 find() 将其引入工作集，然后对该文档运行并发更新也会按预期运行。 此外，使用具有相同查询和设置的 findAndModify 不会出现相同的问题。
这是否按预期工作，还是我遗漏了什么？
设置:
-mongodb java驱动3.0.1
-3节点副本集运行MongoDB版本“2.6.3”
查询:
BasicDBObject query = new BasicDBObject();
query.put("docId", 123L);
collection.update (query, object, true, false);
索引:
name: docId_1
unique: true
key: {"docId":1}
background: true
于 5 月 28 日更新，包含重现该问题的示例代码。 按如下方式在本地运行 MongoDB(请注意，测试将写入大约 4 GB 的数据): ./mongodb-osx-x86_64-2.6.10/bin/mongod --dbpath/tmp/mongo 运行以下代码，重新启动数据库，注释掉“fillUpCollection(testMongoDB.col1, value, 0, 300);”，然后再次运行代码。根据机器的不同，您可能需要调整一些数字才能看到异常。
package test;
import com.mongodb.BasicDBObject;
import com.mongodb.DBCollection;
import com.mongodb.DBObject;
import com.mongodb.Mongo;
import com.mongodb.MongoClient;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
public class TestMongoDB {
public static final String DOC_ID = "docId";
public static final String VALUE = "value";
public static final String DB_NAME = "db1";
public static final String UNIQUE = "unique";
public static final String BACKGROUND = "background";
private DBCollection col1;
private DBCollection col2;
private static DBCollection getCollection(Mongo mongo, String collectionName) {
DBCollection col = mongo.getDB(DB_NAME).getCollection(collectionName);
BasicDBObject index = new BasicDBObject();
index.append(DOC_ID, 1);
DBObject indexOptions = new BasicDBObject();
indexOptions.put(UNIQUE, true);
indexOptions.put(BACKGROUND, true);
col.createIndex(index, indexOptions);
return col;
}
private static void storeDoc(String docId, DBObject doc, DBCollection dbCollection) throws IOException {
BasicDBObject query = new BasicDBObject();
query.put(DOC_ID, docId);
dbCollection.update(query, doc, true, false);
//dbCollection.findAndModify(query, null, null, false, doc, false, true);
}
public static void main(String[] args) throws Exception{
final String value = new String(new char[1000000]).replace('\0', 'a');
Mongo mongo = new MongoClient("localhost:27017");
final TestMongoDB testMongoDB = new TestMongoDB();
testMongoDB.col1 = getCollection(mongo, "col1");
testMongoDB.col2 = getCollection(mongo, "col2");
fillUpCollection(testMongoDB.col1, value, 0, 300);
//restart Database, comment out previous line, and run again
fillUpCollection(testMongoDB.col2, value, 0, 2000);
updateExistingDocuments(testMongoDB, value);
}
private static void updateExistingDocuments(TestMongoDB testMongoDB, String value) {
List<String> docIds = new ArrayList<String>();
for(int i = 0; i < 10; i++) {
docIds.add(new Random().nextInt(300) + "");
}
multiThreadUpdate(testMongoDB.col1, value, docIds);
}
private static void multiThreadUpdate(final DBCollection col, final String value, final List<String> docIds) {
Runnable worker = new Runnable() {
@Override
public void run() {
try {
System.out.println("Started Thread");
for(String id : docIds) {
storeDoc(id, getDbObject(value, id), col);
}
} catch (Exception e) {
System.out.println(e);
} finally {
System.out.println("Completed");
}
}
};
for(int i = 0; i < 8; i++) {
new Thread(worker).start();
}
}
private static DBObject getDbObject(String value, String docId) {
final DBObject object2 = new BasicDBObject();
object2.put(DOC_ID, docId);
object2.put(VALUE, value);
return object2;
}
private static void fillUpCollection(DBCollection col, String value, int from, int to) throws IOException {
for(int i = from ; i <= to; i++) {
storeDoc(i + "", getDbObject(value, i + ""), col);
}
}
}
第二次运行的示例输出:
Started Thread
Started Thread
Started Thread
Started Thread
Started Thread
Started Thread
Started Thread
Started Thread
com.mongodb.DuplicateKeyException: Write failed with error code 11000 and error message 'insertDocument :: caused by :: 11000 E11000 duplicate key error index: db1.col1.$docId_1 dup key: { : "290" }'
Completed
com.mongodb.DuplicateKeyException: Write failed with error code 11000 and error message 'insertDocument :: caused by :: 11000 E11000 duplicate key error index: db1.col1.$docId_1 dup key: { : "170" }'
Completed
com.mongodb.DuplicateKeyException: Write failed with error code 11000 and error message 'insertDocument :: caused by :: 11000 E11000 duplicate key error index: db1.col1.$docId_1 dup key: { : "241" }'
Completed
com.mongodb.DuplicateKeyException: Write failed with error code 11000 and error message 'insertDocument :: caused by :: 11000 E11000 duplicate key error index: db1.col1.$docId_1 dup key: { : "127" }'
Completed
com.mongodb.DuplicateKeyException: Write failed with error code 11000 and error message 'insertDocument :: caused by :: 11000 E11000 duplicate key error index: db1.col1.$docId_1 dup key: { : "120" }'
Completed
com.mongodb.DuplicateKeyException: Write failed with error code 11000 and error message 'insertDocument :: caused by :: 11000 E11000 duplicate key error index: db1.col1.$docId_1 dup key: { : "91" }'
Completed
com.mongodb.DuplicateKeyException: Write failed with error code 11000 and error message 'insertDocument :: caused by :: 11000 E11000 duplicate key error index: db1.col1.$docId_1 dup key: { : "136" }'
Completed
Completed
最佳答案
这看起来像是 MongoDB 的一个已知问题，至少在 2.6 版之前是这样。他们建议的修复方法是让您的代码在出错时重试更新插入。 https://jira.mongodb.org/browse/SERVER-14322
关于java - 当文档不在工作集中时，使用 upsert 和唯一索引原子性进行 MongoDB 更新，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/30404513/