So I have a Perl script on a server. (Linux...). The script takes about 3+ minutes to fully complete, (this is normal for my script). Although the server keeps disconnecting, and my browser says that the server is not responding (it timed out I guess). How can I keep the connection alive for over 3+ minutes? (The client is just waiting for a response from the server. Nothing else on the client side is happening)...
Is this even possible?
If the server is closing the connection, you need to increase the server (Apache?) script timeout, which will be a parameter to mod_cgi or mod_cgid (depending on which one you're using). If you cannot change the Apache configuration then you might experiment with sending an innocuous HTTP header (i.e. Connection: keepalive, which is the default anyway) immediately before starting your processing. This will probably be sufficient to cause Apache not to give up waiting.
Related
I have an issue and I hope you can help me a bit.
I have to implement fast forwarding time, because I need to test something. I've wrote a python script which increment the system time with 5 seconds for every 1 real second. (5 times faster).
Then my jboss fails with some hornetq timeouts.
Do you have any ideas how I can fix this?
03/09/18 09:18:00,107 WARN
[org.hornetq.core.protocol.core.impl.RemotingConnectionImpl] (hornetq-
failure-check-thread) Connection failure has been detected: Did not
receive data from invm:0. It is likely the client has exited or crashed
without closing its connection, or the network between the server and
client has failed. You also might have configured connection-ttl and
client-failure-check-period incorrectly. Please check user manual for
more information. The connection will now be closed. [code=3]
The underlying issue is that changing the time breaks the connection-failure-detection algorithm used by the broker. The broker thinks it isn't receiving "ping" packets from clients at the proper time because you're forcing time to pass at 5x the normal rate. There is no way to fix this for remote clients aside from disabling or extending the connection TTL. However, for in-vm connections you could apply the fix from https://issues.jboss.org/browse/HORNETQ-1314 (which is not resolved in the version of HornetQ you are using) to the branch of HornetQ you're currently using and rebuild. If you don't want to rebuild you could upgrade to a version of JBoss AS (or Wildfly) which contains this fix.
I'm using LWP::UserAgent to communicate with webservices on several servers; the servers are contacted one at a time. Each response might take up to 30 minutes to finish, so I set the LWP timeout to 30 minutes.
Unfortunately the same timeout also applies, if the server is not reachable at all (e.g. the webserver is down). So my application waits 30 minutes for a server, which is not running.
Is it feasable to set two seperate timeouts?
a short one, which waits for the connection to be established.
a longer one, which waits for the response, once the connection has been established.
The same timeout doesn't "also apply" if the server is not reachable. The timeout option works in a very specific way:
The request is aborted if no activity on the connection to the server is
observed for timeout seconds. This means that the time it takes for the
complete transaction and the request() method to actually return might be
longer.
As long as data is being passed, the timeout won't be triggered. You can use callback functions (see the REQUEST METHODS section of the docs) to check how long data transfer has been going on, and to exit entirely if desired.
For example http://www.utorrent.com/testport?port=12345
How does this work? Can the server side script attempt to open a socket?
There are many ways of accomplishing this through server-side scripting. As #Oded mentioned, most server-side handlers are capable of initiating socket connections on arbitrary ports, and most of those even have dedicated port-scanning packages/libraries (PHP has one in the PEAR repository, Python's 'socket' module makes this type of tasks a breeze, etc...)
Keep in mind that on shared host platforms, socket connections are typically disabled for security purposes.
Another way that is also very easy to accomplish is to use a command-line port-scanner such as nmap from your server-side script. i.e in PHP, you would do echo ``nmap -p $port $ip\
The server side script will try to open a connection on the specified port to the originating IP.
If there is no response (the attempt will timeout), this would be an indication that the port is not open.
The server can try, as #Oded said. But that doesn't ensure the receiver will respond.
Typically, something like this happens:
The URL request contains instructions about which port to access. The headers that your browser sends include information about where the request is originating from.
Before responding to the request, the server tries to open a port and checks if this is successful. It waits a while before timing out.
The webpage is rendered dynamically based on the results of this test.
The response is returned to you containing the results.
Sometimes steps (2) and (3) will be replaced with an AJAX callback, which allows the response to return sooner.
I have a server and client program on the same machine. The server is part of an application- it can start and stop arbitrarily. When the server is up, I want the client to connect to the server's listening socket. There are win32 functions to wait on file system changes (ReadDirectoryChangesW) and registry changes (RegNotifyChangeKeyValue)- is there anything similar for network changes? I'd rather not have the client constantly polling.
There is no such Win32 API, however this can be easily accomplished by using an event. The client would wait on that event to be signaled. The server would signal the event when it starts up.
The related API that you will need to use is CreateEvent, OpenEvent, SetEvent, ResetEvent and WaitForSingleObject.
If your server will run as a service, then for Vista and up it will run in session 0 isolation. That means you will need to use an event with a name prefixed with "Global\".
You probably do have a good reason for needing this, but before you implement this please consider:
Is there some reason you need a connect right away? I see this as a non issue because if you perform an action in the client, you can at that point make a new server connection.
Is the server starting and stopping more frequently than the client? You could switch roles of who listens/connects
Consider using some form of Windows synchronization, such as semaphore. The client can wait on the synchronization primitive and the server can signal it when it starts up.
Personally I'd use a UDP broadcast from the server and have the "client" listening for it. The server could broadcast a UDP packet every X period whilst running and when the client gets one, if it's not already connected, it could connect.
This has the advantage that you can move the client onto a different machine without any issues (and since the main connection from client to server is sockets already it would be a pity to tie the client and server to the same machine simply because you selected a local IPC method for the initial bootstrap).
What is the best way to access a running mono application via the command line (Linux/Unix)?
Example: a mono server application is running and I want to send commands to it using the command line in the lightest/fastest way possible, causing the server to send back a response (e.g. to stdout).
I would say make a small, simple controller program that takes in your required command line arguments and uses remoting to send the messages to the running daemon.
This would be similar to the tray icon controller program talking to the background service that is prevalent in most Windows service patterns.
Mono's gsharp tool is a graphical REPL that lets you Attach to Process.
#Rich B: This is definately a suitable solution, which I already had implemented - however on the server I have to use, the remoting approach takes around 350ms for a single request.
I've measured the time on the server side of the request handling - the request is handled in less than 10ms, so it has to be the starting of the client program and the tcp connection, that takes up the time.
Hence the hope that I can find another way to post the requests to the server application.
You can use the system.net.sockets abstractions to create a service on a TCP port, and then telnet to that port.
Check the library status page; Mono's coverage here is a bit patchy.