[Mono-list] Async sockets and memory leaks in BeginSend

[Nicholas Frechette]

Yes that particular memory leak was present in 2.10.6 for sure and
possibly in 2.10.8 as well. I was told this is claim fixed in master
but haven't tested yet.
Note that this affected all callbacks called from native code. GTK#
was hit pretty bad by this particular leak. If you search the mailing
list with my name you should find the bug report i filled quite
easily.

Regards,
Nicholas

On Wed, May 23, 2012 at 3:50 AM, Rolf Bjarne Kvinge <rolf at xamarin.com> wrote:
> Hi,
>
> Which version of Mono are you using? I believe this particular scenario has
> been improved a lot in mono master, so can you try that if you're not
> already using it?
>
> Rolf
>
> On Mon, May 21, 2012 at 10:51 PM, xplicit <svg at ngs.ru> wrote:
>>
>> I am developing server with mono using async socket model. Currently it's
>> about 500 simultaneously working clients with 20-100 operations per
>> seconds.
>> The code should send messages accordingly theirs creation time, so I use
>> such pattern:
>>
>> Send()
>> {
>>    //Dequeue message from queue. Messages placed in the queue accordingly
>> theirs creation time
>>    SendStateObject state=new SendStateObject();
>>    state.buffer=Dequeue();
>>    state.socket=client;
>>
>>    //some checks in the code were removed, this function is called only
>> when no other send callbacks were ran
>>    client.BeginSend(state.buffer, 0, state.buffer.Length,
>> SocketFlags.None,
>> new AsyncCallback(SendCallback), state);
>>
>> }
>>
>> private void SendCallback(IAsyncResult ar)
>> {
>>    SendStateObject sendState = (SendStateObject)ar.AsyncState;
>>    Socket client = sendState.workSocket;
>>
>>    try
>>    {
>>          client.EndSend(ar);
>>    }
>>    catch() /*Some exceptions handling */
>>    {}
>>    finally
>>    {
>>          sendState.buffer=null;
>>          sendState.workSocket=null;
>>    }
>>
>>    if (SomeItemsInQueue()) Send();
>>
>> }
>>
>> And this code produces huge memory leaks under high load. Profiler says,
>> that there are millions of AsyncCallback objects and
>> System.Net.Sockets.SocketAsyncResult objects.
>>
>> I think, I could minimize number of AsyncCallback objects by creating it
>> only one time in constructor and passing it to BeginSend (I'll check it
>> later), but what to do with SocketAsyncResult (and byte buffers which it
>> contains in)?
>> I don't create this object, it's created inside of BeginSend and in most
>> cases it is not claimed by garbage collector.
>>
>> Maybe I use wrong pattern and must remove calling Send() from the end line
>> of callback, but I don't understand, why these objects could not be freed
>> by
>> GC...
>>
>>
>>
>> --
>> View this message in context:
>> http://mono.1490590.n4.nabble.com/Async-sockets-and-memory-leaks-in-BeginSend-tp4648844.html
>> Sent from the Mono - General mailing list archive at Nabble.com.
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>
>
>
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