Socket connection seems to drop frequently caused by DGCClient

Hello,
I am using RMI with SSL, but I recognize that calling remote methods often takes long time. I have investigated, that the the
createSocket function in my RMISSLClientSocketFactory is called very often and createSocket takes around 3 seconds because I am using SSL with a big key, but this is another story..
Sometimes after more or less 20 seconds the createSocket function is called by the framework, but I don't want to create new sockets very frequently.
In the stack trace I can see the following:
System Thread [RMI RenewClean-[192.168.1.60:2022,ApplicationRMISSLClientSocketFactory@ecb67f]] (Suspended (breakpoint at line 47 in ApplicationRMISSLClientSocketFactory))
ApplicationRMISSLClientSocketFactory.createSocket(String, int) line: 47
TCPEndpoint.newSocket() line: not available
TCPChannel.createConnection() line: not available
TCPChannel.newConnection() line: not available
UnicastRef.newCall(RemoteObject, Operation[], int, long) line: not available
DGCImpl_Stub.dirty(ObjID[], long, Lease) line: not available
DGCClient$EndpointEntry.makeDirtyCall(Set, long) line: not available
DGCClient$EndpointEntry.access$1600(DGCClient$EndpointEntry, Set, long) line: not available
DGCClient$EndpointEntry$RenewCleanThread.run() line: not available
Thread.run() line: not available
The DGCClient seems to be responsible for new socket creation. Is it possible to disable the DGC (distributed garbage collector), or to avoid that a new socket is created?
Addional info: if I start my client and server without making any traffic, a new socket is created exactly every 5 minutes.
thanks in advance,
Armin
www.lyth.de

createSocket function in my RMISSLClientSocketFactory is called very oftenIt shouldn't be. Does your RMISSLClientSocetFactory have an equals() method? It should read like this:
public boolean equals(Object that)
return that != null&& this.getClass() == that.getClass();
}If you're using 1.5 or later you don't even need your own RMISSLClientSocketFactory: see javax.rmi.ssl.*.

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Hi All ,
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I have an issue with a college project I'm working on.
Using Actionscript 3, I made a simple .swf program, an animated, interactive smiley, that 'reacts' to number inputs in a input-box.
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Error #2044: Unhandled securityError:. text=Error #2048: Security sandbox violation: file:///C|/Users/Marko/Desktop/Završni/Flash%20documents/Smiley%5FTCP%5FIP%5Fv4.swf cannot load data from 127.0.0.1:9001.
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Tried adding that particular integer code, ended up with either errors ("use of unspecified variable" and "implicit coercion") , or no effect whatsoever (despite tracing it).
Noticed as well that the earlier socket code had the following for byte reading:
"sock.bytesAvailable > 0" (reads any positive number)
...rather than your new:
"sock.bytesAvailable != 0" (reads any negative/positive number)
Any difference as far as stability/avoiding bugs goes?
So then, I tried something different: Have the program turn the "msg" string variable, into a "sentnumber" number variable. This seemed to work nicely, tracing a NaN for text (expected), or tracing the number of an actual number.
I also did a few alterations to the input box - it now no longer needs the 'enter' key to do the calculation, it updates the animation after any key release.
With all this considered and the requirements of the project, I now have a few goals I want to achieve for the client, in the following order of priority:
1) Have the "sentnumber" number variable be recognized by the inputbox layer, so that it puts it into the input box. So in effect, it goes: Connect -> Send data that is number (NaN's ignored) -> number put into input box -> key press on client makes animation react. I optionally might need a way to limit the number of digits that the animation reacts to (right now it uses 1-3 digit numbers, so if I get sent a huge number, it might cause issues).
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2) After achieving 1), I'll need to have the process be automatic - not requiring a keyboard presses from the client, but happening instantly once the data is sent during a working connection.
- Can this be done by copying the huge amounts of math/calculus code from the inputbox layer, into the socket layer, right under where I create the "sentnumber" variable, and modifying it delicately?
3) The connection still has some usability and user issues - since the connection happens only once, on frame 1, it only connects if I already have a listening server when I run the client, and client can't re-connect if the server socket doesn't restart itself.
I believe to do this, I need to make the connection happen on demand, rather than once at the start.
For the project's requirement, I also need to allow client users to define the IP / port it's going to connect to (since the only alternative so far is editing the client in flash pro).
In other words, I need to make a "Connect" button and two textboxes (for IP and port, respectively), which do the following:
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It seems like making the button should be as simple as putting the existing socket code under the function of a button, but it also seems like it's going to cause issues similar to the 'looping frames' error.
4) Optional addition: Have a scrolling textbox like the AIR server has, to track what the connection is doing on-the-fly.
The end result would be a client that allows user to input IP/Port, connects on button press (optionally tracking/display what the socket is doing via scrollbox), automatically alters the smiley based on what numbers are sent whilst the connection lasts, and on subsequent button presses, makes a new connection after closing off the previous one.
Dropbox link to new client version:
https://www.dropbox.com/s/ybaa8zi4i6d7u6a/Smiley_TCP_IP_v7.fla?dl=0
So, starting from 1), can I, and how can I, get the number variable recognized by "inputbox" layer's code? It keeps giving me 'unrecognized variable' errors.

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Slow Connection that sometimes drops

Office: I have Airport Extreme BS, sim. dualband -n connected to a modem thorugh Ethernet. Set to create a wireless network
Home: In a 40 meters distance from the office I have placed the Time Machine (also the latest model) that backes up the Mac Mini server a work. There is a visual between the AEBS and the TC.
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Transmssion rate: 81
MCS: 4
The connection does not seem stable. Sometimes the connection drops out, causing the backup to fail.
Would it do any good to buy an outdoor repeater placing it on the roof of the office building?
I have another wireless network at home. Could that be intefering with the first one? -And how can that be prevented?

Hans-Ole wrote:
RSSI: -76
On which device do you see that value? It's fairly low and doesn't give you much spread over the probable noise level.
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Would it do any good to buy an outdoor repeater placing it on the roof of the office building?
I'm not familiar with those. You might be able to improve the connect by moving or reorienting either or both stations. You might also try using a different channel or band. In the 5 GHz band try channels 149 and up. In the 2.4 GHz band try channels 1, 6, or 11.
I have another wireless network at home. Could that be interfering with the first one? -And how can that be prevented?
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Socket.connect

I'm trying to write a client application that will connect to a server whenever it becomes available. There are some problems which I hope someone will be able to help, Below is a snippet of the code that makes the connection:
while(alive){
try{
/* part 1*/
Socket s = new Socket();
s.setReuseAddress(true);
s.bind(localAddress);
/* end part 1*/
s.connect(targetAddress);
} catch (Exception e){}
this seems to works fine. However when I place part 1 of the code outside the while loop. the connection will not be made if the server application is up after my connection thread has started running. Isnt Socket.connect suppose to block until a valid connection is made?
Also when running my application (with the code above) over a long period of time, I get a OutOfMemoryException (native memory) when the server application is not present. Do I have to specify some other parameters for the JVM to release the native resources allocated for a socket construction or is this just a bug? I am running the application using java 1.6 on RHEL4 2.6.9-34.ELSMP.
Thank you in advance.

The thread is respawned when then server application
drops thus yes the socket will only make one
connection.Not if you move part 1 out of the loop.If you do that you will attempt multiple connections with the socket, which doesn't work.
Shouldnt the thread block when .connect() fails?Why? Block doing what?
Instead i'm getting a connection refused exception.What else should it do?
No i did not close the socket when I get an exception.You should.
Should the resources be reclaimed since
the socket object would have gone out of scope?Eventually.
I'm running my application on a system with multiple
network cards thus i need to bind it to the intended
address.Why? TCP/IP will find the best route if you don't get in its way. Why not let it?

Java Socket Connection Time out

Goal*
I want to check host/port availability of computers in our network (~100 computers) .. Just check if host is alive and if it has port 445 opened. I want to do this somehow in parallel, so the code execution is as quick as possible.
My implementation*
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        try {
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            InetSocketAddress socketAddress = new InetSocketAddress(ipAddress, 445);
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        } catch (ConnectException ex) {
            //exception thrown
        } catch (IOException ex1) {
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Problem:*
1.
It seems to me, that first ~10-15 connections are created ok, but then my code reaches 'IOException' catch block for every subsequent itteration and ex.getMessage() returns "connection time out" (I try to use different timeout values in the 2nd parameter. Values from 3000 up to 20000).
Is it valid to create 100 separate threads in a loop? Can't I make my NIC to bussy with this ??? What is the maximum ammount of threads, I can create? I did not use threads before, so I have no idea, if max values are near to 10, 100, 1000, or 10000 ..
2.
After my code is executed, I enter 'netstat -an' command in my command line and I get bunch of connections, which report status of SYN_SENT for several connections.
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TCP 10.20.11.140:4560 10.30.11.142:445 SYN_SENT
TCP 10.20.11.140:4561 10.30.11.171:445 SYN_SENT
TCP 10.20.11.140:4562 10.30.11.143:445 SYN_SENT
TCP 10.20.11.140:4563 10.30.12.12:445 SYN_SENT
TCP 10.20.11.140:4564 10.30.12.11:445 SYN_SENT
TCP 10.20.11.140:4565 10.30.12.21:445 SYN_SENT
TCP 10.20.11.140:4566 10.30.11.150:445 SYN_SENT
I also feel, that my computer network response (e.g. firefox browsing) is a bit slower ..
How shall I handle this problem properly?
Thx in advance,
Juraj

kajbj wrote:
tschodt wrote:
kajbj wrote:
The documentation for netstat explains what SYN_SENT is, but
I don't know why you have them.The app has asked the TCP stack to transmit SYN
the TCP stack is now waiting for SYN-ACK.
If there is no host at that IP address or a host that drops connections (SYN packets) for TCP port 445
there will never be a SYN-ACK.
After a few minutes the TCP stack will time out the connection attempt.Yes, I was rather commenting on why his hosts aren't answering. I thought that his case was that all of them should answer :)Akkurat. I was answering more for clarification.
Someone who does not know your posting history could easily assume you meant
it was a mystery why netstat was showing SYN_SENT.
And I figured it would not harm to hint that one possible reason would be that those machines are powered off (no host).

Socket connection seems to drop frequently caused by DGCClient

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