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我目前正在使用MongoDB Java API开发一个项目。我一直在做这个项目，但最近遇到了一个我无法解决的问题。我正试图建立一个容错的数据库系统。为了模拟数据库崩溃，我将程序连接到我所做的Mongodb服务器，执行简单的读取或写入操作，然后关闭数据库服务器。我原本以为这会导致某些方法，我打电话来抛出一个MongoException我可以捕捉然后从数据库崩溃中恢复。然而，我得到一个奇怪的堆栈跟踪，说我抛出一个EOFException，等等。以下是堆栈跟踪本身。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.是我使用来验证我赶上某些例外打印报表。下面是相关代码：
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，当我打电话cursor.hasNext()错误发生。我实际上还在捕捉由于Caught exception而引发的异常。但是，我仍然得到一个堆栈跟踪，就好像它没有被捕获一样。我怀疑这与DBPortPoolgotError()方法有关，但我已经查看了此方法的代码，并且无法确定它实际正在执行的操作，甚至无法确定它如何被调用。 （GrepCode link）
如上所述，我认为当这个特定的Mongo对象上的调用因数据库不再有效而失败时，这种类型的代码的行为将会抛出MongoException。任何人都可以提供的帮助将不胜感激！
您连接的端口是否正确？这是否适用于其他命令？有没有办法让服务器日志尾巴可以确认mongo正在接收并正确回应查询？ – ranman 2013-03-07 19:40:41