Why networkstream.write block?

Question

I have client server project. i have a problem in sending data from server to clients.

    private bool SendPack(object client, string data)
    {
        lock (this)
        {
            try
            {
                NetworkStream clientStream = tcpServer.GetStream();

                byte[] Pack= ClsEncryption.GetEncrypt(data);

                clientStream.Write(Pack, 0, Pack.Length);
                clientStream.Flush();

                return true;
            }

            catch
            {                    
                return false;
            }
        }
    }

although i use lock, when write command runs, everything ruin. i mean nothing send and the write does not return(like blocking). should i use asynch methods by using beginwrite or not? how can i check if the networkstream is ready to write and would not block. i use clientstream.canwrite, but it was not useful.

I need the fastest and most reliable way to send data. Any Idea?

Offtopic suggestion: You should avoid using lock(this). See http://stackoverflow.com/questions/251391/why-is-lockthis-bad. — Ilian, Aug 21 '11 at 08:52
What is `tcpServer`? How do you create it? Please post more relevant code. — Shadow The GPT Wizard, Aug 21 '11 at 08:57
it's the client object which server tries to send data to it. — maryam mohammadi, Aug 21 '11 at 09:54

score 0 · Answer 1 · answered Aug 21 '11 at 10:32

If there are simultaneous read operations with this stream on other thread, and if read operations uses lock on same instance, threads will possably deadlock. If that is true, use different instances for locking read and write operations or send | read data outside the lock statement.

score -1 · Answer 2 · answered Aug 21 '11 at 08:41

-1

According to the documentation you can use the CanWrite property:

if (clientStream.CanWrite)
{
    clientStream.Write(Pack, 0, Pack.Length);
    clientStream.Flush();
    return true;
}

answered Aug 21 '11 at 08:41

Shadow The GPT Wizard

66,030
26
140
208

2

I do not believe CanWrite is related to this. In fact, I'd pretty much expect this to be always true in this case – Marc Gravell Aug 21 '11 at 08:49
@Marc I would expect it to answer the "check if the networkstream is ready to write" question.. otherwise what is its purpose? – Shadow The GPT Wizard Aug 21 '11 at 08:54
to indicate that it is a stream that supports output operations - which it does – Marc Gravell Aug 21 '11 at 08:55
OK, I'll try to dig more details from the OP then. – Shadow The GPT Wizard Aug 21 '11 at 08:56
I used canwrite property, but ecen when it returns true, the write command block and does not return. – maryam mohammadi Aug 21 '11 at 09:52

Why networkstream.write block?

2 Answers2