[rabbitmq-discuss] rabbitmq-c memory leak?

Thu Apr 10 14:21:30 BST 2014

Do you get the same problems building it off of the master branch?
On Thu, Apr 10, 2014 at 4:46 AM, Dushin Fred <fred at dushin.net> wrote:

> Sorry, I should have been more clear.
>
> The original issue I hit was from a build off the 2.3 tag (418f31f).  So
> the patch I applied was slightly different:
>
> > git diff
> diff --git a/src/ChannelImpl.cpp b/src/ChannelImpl.cpp
> index 9749556..864502b 100644
> --- a/src/ChannelImpl.cpp
> +++ b/src/ChannelImpl.cpp
> @@ -152,6 +152,7 @@ amqp_channel_t ChannelImpl::GetChannel()
>
>  void ChannelImpl::ReturnChannel(amqp_channel_t channel)
>  {
> +       amqp_maybe_release_buffers_on_channel(m_connection, channel);
>      m_channels.at(channel) = CS_Open;
>      m_last_used_channel = channel;
>  }
>
> I fully respect that this may not be the "right" fix, but in my limited
> scenario (the sender.cpp program I posted off github), it does the trick.
>
> I have done zero analysis of the right fix, but I'd be happy to crack open
> the code and look into it, if the root cause of the bug is not immediately
> evident to you.  Otherwise, if you have any thoughts, feel free to let me
> know.
>
> And of course I would prefer (as I suspect many would) that the fix go
> into master, as this bug seems to effectively render the C++ client library
> unsuitable for production, and I would prefer not to maintain a fix that is
> not endorsed by the author/maintainer.
>
> -Fred
>
> On Apr 10, 2014, at 1:11 AM, Alan Antonuk <alan.antonuk at gmail.com> wrote:
>
> What version of SimpleAmqpClient are you using? The lines surrounding your
> change don't seem to match what is currently<https://github.com/alanxz/SimpleAmqpClient/blob/master/src/ChannelImpl.cpp#L153>in the master branch of SimpleAmqpClient. I believe behavior you're seeing
> was addressed a while ago (see Issue #56<https://github.com/alanxz/SimpleAmqpClient/issues/56>).
> Please download the master branch and build from that, you will also need
> rabbitmq-c v0.4.1 or newer for this to work.
>
> FYI: the patch you are suggesting using will likely cause undefined
> behavior. Because of the way rabbitmq-c's memory management works, the
> SimpleAmqpClient cannot call amqp_maybe_release_buffers() until it no
> longer holds any references to frames returned from
> amqp_simple_wait_frame(). Once amqp_maybe_release_buffers() (or
> amqp_maybe_release_buffers_on_channel()) any outstanding frames are
> considered freed and their use will lead to undefined behavior.
> SimpleAmqpClient maintains a list of frames that it has seen from the
> broker, in ChannelImpl::MaybeReleaseBuffersOnChannel<https://github.com/alanxz/SimpleAmqpClient/blob/master/src/ChannelImpl.cpp#L446> it
> checks to see if there are any frames that it still has a reference to
> before calling amqp_maybe_release_buffers()
>
> -Alan
>
>
> On Wed, Apr 9, 2014 at 3:17 PM, Dushin Fred <fred at dushin.net> wrote:
>
>> That works for me, too.  Thanks, Abhay.
>>
>> Alan, would you like a pull request?  Is there a timeline for folding
>> this an the other recent fixes into master?  Anything I can do to help
>> expedite?
>>
>> -Fred
>>
>> On Apr 9, 2014, at 4:54 AM, Abhay Rajure <arajure at gmail.com> wrote:
>>
>> Try this --
>>
>> In File SimpleAmqpClient/src/ChannelImpl.cpp,
>> call amqp_maybe_release_buffers_on_channel() in ReturnChannel().
>>
>> void ChannelImpl::ReturnChannel(amqp_chanel_t channel)
>> {
>>   +amqp_maybe_release_buffers_on_channel(m_connection, channel);
>>    m_free_channels.push(channel);
>> }
>>
>>
>>
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>>
>>
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