CODEWITHSUNDEEP
javaserializationobjectinputstreamobjectoutputstream
Andrew
Andrew

Reputation: 378

ObjectInputStream blocking in readObject()

I'm writing a client/server application in which server sends serializable objects to client via ObjectOutputStream (i'll call it oos from now on) and client gets 'em with ObjectInputStream ("ois" from now on).

Now, since the server is executed first, I initialize the oos first. As it should be. Here's how I initialize it: 

OutputStream outStream=incoming.getOutputStream();
DataOutputStream outToClient=new DataOutputStream(outStream);
outToClient.flush();
ObjectOutputStream oos = new ObjectOutputStream(outStream);  
oos.flush();

Then I start the client and I initialize the ois with these line:

inStream = clientSocket.getInputStream();
ObjectInputStream ois = new ObjectInputStream(inStream);

From now on, the server side will send many objects on the same stream this way:

oos.writeUnshared(wishes);

in a while loop. The problem is: when I execute this goddamn code on my pc alone, it's all good. No problems at all. When I try on two different machines, deadlock appears. The client side remains hanging on this line forever: 

tempWishes = (ArrayList<String>) ois.readObject();

Feel free to ask more details. I didn't share the whole client and server code because it's like 500 lines of code.

Upvotes: 0

Views: 2728

Answers (2)

Cameron Skinner
Cameron Skinner

Reputation: 54276

This looks suspicious:

DataOutputStream outToClient=new DataOutputStream(outStream);
ObjectOutputStream oos = new ObjectOutputStream(outStream);

Both outToClient and oos are writing to the same underlying stream. This is likely to cause weirdness.

@EJP's suggestion that you remove the DataOutputStream is a good one because the DataOutputStream class isn't what you're after (since you're writing objects), and you almost certainly want a single chain of OutputStreams.

Upvotes: 1

Diegomanas
Diegomanas

Reputation: 162

Have you tried using ois.readUnshared() instead of ois.readObject(). Even though it may no be the whole issue, it may be some other, it's good practice to couple write and reads.

Let me know if this fixed it.

Upvotes: 0

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