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我目前正在使用MongoDB Java API開發一個項目。我一直在做這個項目，但最近遇到了一個我無法解決的問題。我正試圖建立一個容錯的數據庫系統。爲了模擬數據庫崩潰，我將程序連接到我所做的Mongodb服務器，執行簡單的讀取或寫入操作，然後關閉數據庫服務器。我原本以爲這會導致某些方法，我打電話來拋出一個MongoException我可以捕捉然後從數據庫崩潰中恢復。然而，我得到一個奇怪的堆棧跟蹤，說我拋出一個EOFException，等等。以下是堆棧跟蹤本身。MongoDB Java API com.mongodb.DBPortPool gotError
Mar 04, 2013 8:06:15 PM com.mongodb.DBPortPool gotError
WARNING: emptying DBPortPool to polaris.cs.wcu.edu/152.30.5.5:12345 b/c of error
java.io.EOFException
at org.bson.io.Bits.readFully(Bits.java:48)
at org.bson.io.Bits.readFully(Bits.java:33)
at org.bson.io.Bits.readFully(Bits.java:28)
at com.mongodb.Response.<init>(Response.java:40)
at com.mongodb.DBPort.go(DBPort.java:124)
at com.mongodb.DBPort.call(DBPort.java:74)
at com.mongodb.DBTCPConnector.innerCall(DBTCPConnector.java:282)
at com.mongodb.DBTCPConnector.call(DBTCPConnector.java:256)
at com.mongodb.DBApiLayer$MyCollection.__find(DBApiLayer.java:289)
at com.mongodb.DBApiLayer$MyCollection.__find(DBApiLayer.java:274)
at com.mongodb.DBCursor._check(DBCursor.java:368)
at com.mongodb.DBCursor._hasNext(DBCursor.java:459)
at com.mongodb.DBCursor.hasNext(DBCursor.java:484)
at edu.wcu.cs.capstone.view.AbstractViewEngine.getView(AbstractViewEngine.java:57)
at edu.wcu.cs.capstone.transaction.ServerTransactionManager.getView(ServerTransactionManager.java:52)
at edu.wcu.cs.capstone.transaction.ServerTransactionManager.run(ServerTransactionManager.java:183)
at java.lang.Thread.run(Thread.java:722)
Caught exception
Mar 04, 2013 8:06:15 PM com.mongodb.DBPortPool gotError
WARNING: emptying DBPortPool to polaris.cs.wcu.edu/152.30.5.5:12345 b/c of error
java.io.IOException: couldn't connect to [polaris.cs.wcu.edu/152.30.5.5:12345] bc:java.net.ConnectException: Connec
at com.mongodb.DBPort._open(DBPort.java:214)
at com.mongodb.DBPort.go(DBPort.java:107)
at com.mongodb.DBPort.call(DBPort.java:74)
at com.mongodb.DBTCPConnector.innerCall(DBTCPConnector.java:282)
at com.mongodb.DBTCPConnector.call(DBTCPConnector.java:256)
at com.mongodb.DBApiLayer$MyCollection.__find(DBApiLayer.java:289)
at com.mongodb.DBApiLayer$MyCollection.__find(DBApiLayer.java:274)
at com.mongodb.DBCursor._check(DBCursor.java:368)
at com.mongodb.DBCursor._hasNext(DBCursor.java:459)
at com.mongodb.DBCursor.hasNext(DBCursor.java:484)
at edu.wcu.cs.capstone.view.AbstractViewEngine.getView(AbstractViewEngine.java:61)
at edu.wcu.cs.capstone.transaction.ServerTransactionManager.getView(ServerTransactionManager.java:52)
at edu.wcu.cs.capstone.transaction.ServerTransactionManager.run(ServerTransactionManager.java:183)
at java.lang.Thread.run(Thread.java:722)
DB is down.
Exception in thread "Thread-3" java.lang.NullPointerException
at edu.wcu.cs.capstone.transaction.ServerTransactionManager.run(ServerTransactionManager.java:184)
at java.lang.Thread.run(Thread.java:722)
的Caught Exception和DB is down.是我使用來驗證我趕上某些例外打印報表。下面是相關代碼：
public View getView(Mongo mongo, Query query) throws MongoException,
EOFException {
String connected = "";
try {
connected = mongo.getConnectPoint();
} catch (Exception e) {
throw new MongoException("Error.");
}
System.out.println("Connected: " + connected);
DB db = mongo.getDB(query.getServer());
List<DBObject> viewList = new ArrayList<DBObject>();
DBCollection collection = db.getCollection(query.getCollection());
DBCursor cursor = collection.find(query.getQuery(), excludeID);
try {
cursor.hasNext();
} catch (Exception e) {
System.out.println("Caught exception");
}
while (cursor.hasNext()) {
viewList.add(cursor.next());
}
return new View(viewList);
}
正如你可以看到，當我打電話cursor.hasNext()錯誤發生。我實際上還在捕捉由於Caught exception而引發的異常。但是，我仍然得到一個堆棧跟蹤，就好像它沒有被捕獲一樣。我懷疑這與DBPortPoolgotError()方法有關，但我已經查看了此方法的代碼，並且無法確定它實際正在執行的操作，甚至無法確定它如何被調用。 （GrepCode link）
如上所述，我認爲當這個特定的Mongo對象上的調用因數據庫不再有效而失敗時，這種類型的代碼的行爲將會拋出MongoException。任何人都可以提供的幫助將不勝感激！
您連接的端口是否正確？這是否適用於其他命令？有沒有辦法讓服務器日誌尾巴可以確認mongo正在接收並正確迴應查詢？ – ranman 2013-03-07 19:40:41