[Kde-bindings] [Bug 108650] New: memory leak in qtruby? (Qt::Socket)

[Caleb Tennis]

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http://bugs.kde.org/show_bug.cgi?id=108650         
           Summary: memory leak in qtruby? (Qt::Socket)
           Product: bindings
           Version: unspecified
          Platform: Gentoo Packages
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: NOR
         Component: general
        AssignedTo: kde-bindings kde org
        ReportedBy: caleb gentoo org


Version:            (using KDE KDE 3.4.1)
Installed from:    Gentoo Packages
OS:                Linux

I've been chasing a memory leak in a couple of my programs now for sometime, and I believe I have found it.  Please accept my apologies if I'm missing something obvious here.  Bear with me as I try to describe it.

I have a few qtruby  programs which, after running for a few days, tend to die with OOM errors after growing to very large memory consumption.  I also tried manually calling the garbage collector every second while the program was running to no avail.  Other programs did not exhibit this behavior, so after some tests, I found out what was causing hte leak:

I have a Qt::Object derived class which houses a Qt::Socket that I use for communication with various servers around our building.  My Qt::Object class defines this connection:

    Qt::Object::connect( socket, SIGNAL('readyRead()'), self, SLOT('MessageReceivedSlot()'))

And this slot is defined as:

  def MessageReceivedSlot
    emit MessageSignal( socket readLine chomp) while( socket canReadLine)
  end

And this is where the memory leak occurs.

I made a simple test case to reproduce it.  I created a small TCP server which just sends out data over and over again to anything that connects to it:

require 'socket'
port = 1999.to_i
server = TCPServer.new('localhost', port)
while (session = server.accept)
  idx = 0
  while true
    20.times { session.puts "Request: Blah #{idx}" }
    idx = idx + 1
    sleep 1
  end
end

And then I created a small program which uses this socket class to connect to the server and just continue to receive the messages.  I even changed the receive slot to NOT emit the signal, figuring that that may be the problem:

  def MessageReceivedSlot
     socket readLine chomp while( socket canReadLine)
  end

So all my class does now is continue to receive data, and readLine it, but not do anything with it.  I am also calling the garbage collector quite often to make sure I'm not seeing anything funny.

Over time, the programs memory consumption continues to grow and grow.  It may start out at something like 22000K memory, and after 48 hours will be around 150000K, and will continue until it gets an OOM error.

My *hunch* is that there's something spurious going on with string to Qt::String conversion, perhaps a QString is getting created somewhere as a child of my socket and it's never being disposed of, but I don't know for sure.  I'm currently running in a debugger in an attempt to see what is causing the continual growth of memory, but any thoughts would be helpful.