java - 如何在Java中正确使用MongoDB多线程？

Question

我正在使用 mongo-java-driver-3.0.0 库在我的 MongoDB 实例中插入许多数据。问题是，当我尝试使用多个线程(模拟多个用户)时，在进行一些插入后会发生以下错误:

INFORMAÇÕES: Closed connection [connectionId{localValue:816}] to
  localhost:27017 because the pool has been closed. Exception in thread
  "user_4" com.mongodb.MongoSocketReadException: 
  Prematurely reached end of stream

我调用实例并进行插入的代码是:

public static FachadaMongo getInstancia() {
    if (instancia == null) {
        instancia = new FachadaMongo();
    }
    return instancia;
}

public MongoDatabase getDB(String HOST, String PORT, String DB_NAME) {
    MongoClientOptions.Builder builder = new MongoClientOptions.Builder();
    //build the connection options  
    builder.maxConnectionIdleTime(60000);//set the max wait time in (ms) 60 segundos
    MongoClientOptions opts = builder.build();

    int port = Integer.parseInt(PORT);
    MongoClient mongoClient = new MongoClient(new ServerAddress(HOST, port), opts);
    MongoDatabase db = mongoClient.getDatabase(DB_NAME);
    return db;
}

public MongoCollection getColecao(String HOST, String PORT, String DB_NAME, String colecao) {
    MongoCollection col = FachadaMongo.getInstancia().getDB(HOST, PORT, DB_NAME).getCollection(colecao);
    return col;
}

public void insert(String HOST, String PORT, String DB_NAME, Document documento) {
    this.getColecao(HOST, PORT, DB_NAME, "documentos").insertOne(documento);
}

即使我仅在一个线程中使用此代码，一段时间后也会出现相同的错误。使用多个线程，错误来得更快。如果有人可以帮助我，我将不胜感激，我大学的最终工作取决于此。

Answer 1

经过多次测试，我可以找到问题的原因。在 getDB 方法中，我为数据库中的每个插入创建一个新连接。将连接数乘以客户端数，我的数据库“过度连接”了。我通过替换行来修复它

MongoClient mongoClient = new MongoClient(new ServerAddress(HOST, port), opts);

用行:

    MongoClient mongoClient;

在类(class)的开头，以及以下行:

if (mongoClient == null) mongoClient = new MongoClient(new ServerAddress(HOST, port), opts);

在我删除的另一个位置。

现在运行良好。