Re: FW: OM 2.4.1 and transport destroy also destroys mama_publisher


Dmitri Fedorov <dfedorov.solace@...>
 

Hi,

I've looked at Reed's sample he gave to us and, indeed, it crashes with double delete.

In our opinion to accommodate this particular application logic (destroy call on the publisher and deleting of the publisher on the publisher callback) a patch is needed to be applied in the OpenMAMA layer.

We have two different approaches we could suggest to OpenMAMA for this patch.

Our testing tool deletes the publisher class instance right after calling its “destroy” method, like so:

​> mama_log(MAMA_LOG_LEVEL_NORMAL, "delete publisher");
> pub->destroy();
our testing tool add this --> delete pub;


Regards,
Dmitri Fedorov
Software Architect
Solace Systems, Inc.
Ottawa, ON Canada

Solace Systems accepts no liability for the content of this email, or for the consequences of any actions taken on the basis of the information provided, unless that information is subsequently confirmed in writing. Any views or opinions presented in this email are solely those of the author and do not necessarily represent those of Solace Systems.

On 14 July 2016 at 14:17, Alpert, Reed via Openmama-dev <openmama-dev@...> wrote:

Hi,

 

I uploaded om_241_transport_pub_destroy.cpp into the jpmc incoming ftp dir.

It should crash when ran as-is (may need some hard-coded string changes for your end), and then on line 64 if you turn that code on it will be ok.

 

It’s the delete call in the onDestroy that does it.

 

Thanks,

 

Reed.

 


Reed Alpert | Corporate & Investment Bank | Market Data Services | J.P. Morgan | 4 Metrotech Center, 23rd Floor, Brooklyn, NY 11245 | T: 718.242.5198  | M: 917.414.4613 | reed.alpert@...

Alternate Contact:  CIB Market Data Services Engineers | CIB_Market_Data_Services_Engineers@...

 

 

From: Stuart Beattie [mailto:sbeattie@...]
Sent: Thursday, July 14, 2016 1:51 PM
To: Stuart Beattie; Alpert, Reed; openmama-dev@...
Subject: RE: [Openmama-dev] FW: OM 2.4.1 and transport destroy also destroys mama_publisher

 

Hi Reed,

 

I was looking at this and trying to reproduce exactly what you were seeing but wasn’t able to see a core, which makes me think I might be misunderstanding something.

 

I was wondering if you had a trivial example/code/pseudocode that shows exactly the steps taken to make this crash?

 

Thanks

Stuart

 

STUART BEATTIE

Senior Software Engineer

 

O. +44 28909 93365

M.

sbeattie@...

 

Adelaide Exchange Building, 2nd Floor, 24-26 Adelaide Street, Belfast, BT2 8GD

velatradingtech.com | @vela_tt

 

 

From: openmama-dev-bounces@... [mailto:openmama-dev-bounces@...] On Behalf Of Stuart Beattie
Sent: 13 July 2016 10:25
To: Alpert, Reed <reed.alpert@...>; openmama-dev@...
Subject: [Openmama-dev] FW: OM 2.4.1 and transport destroy also destroys mama_publisher

 

Apologies – originally sent this out on Monday but I think it may have been rejected from the mailing list due to not updating my subscription with my new Vela email address.

 

Hi Reed,

 

I don’t think we’ve seen this one – although perhaps others have, but you’re the first to report it.  I’ll have to take more of a look at this, especially this –

 

>> Is the code for a transport to trigger publishers to destroy themselves sufficiently embedded that it could not be removed since existing apps depend on it?

 

I’m currently looking through this to confirm just how necessary this is.  Also, this is a good point –

 

>> It’s probably reasonable to assume that if an app is destroying its transport that it will not destroy its publishers after that.

 

The transport should be the last object destroyed anyway, ie all other MAMA objects should be destroyed before it – but previously the fate of publishers probably didn’t matter that much.

 

Thanks

Stuart

 

STUART BEATTIE

Senior Software Engineer

 

O. +44 28909 93365

M.

sbeattie@...

 

Adelaide Exchange Building, 2nd Floor, 24-26 Adelaide Street, Belfast, BT2 8GD

velatradingtech.com | @vela_tt

 

 

From: openmama-dev-bounces@... [mailto:openmama-dev-bounces@...] On Behalf Of Alpert, Reed via Openmama-dev
Sent: 07 July 2016 20:33
To: openmama-dev@...
Subject: [Openmama-dev] OM 2.4.1 and transport destroy also destroys mama_publisher

 

Hi,

 

Testing with OM 2.4.1.

 

If a C++/MamaPublisher is not destroyed before the C++/MamaTransport is destroyed, then the C/mamaTransport will notify each C/mamaPublisher that the transport is going away, and the mamaPublisher will call destroy on itself. This triggers the onDestroy callbacks, which vector up to the C++ layer, but the destroy was never called on the C++ object, creating a crash in the tear-down (in my case when the mamaPublisher tries to destroy its list for a 2nd time).

 

I think in OM 2.3 and before the absence of the onDestroy cb prevented this bug from occurring, but it still seems incorrect to destroy the C/mamaPublisher if there is a C++/MamaPublisher holding it. It’s probably reasonable to assume that if an app is destroying its transport that it will not destroy its publishers after that.

 

When destroying the MamaPublisher before the MamaTransport this does not occur since the mamaPublisher is removed from the transport.

 

Is the code for a transport to trigger publishers to destroy themselves sufficiently embedded that it could not be removed since existing apps depend on it?

 

Has anyone else seen this in testing?

 

Thanks,

 

Reed.

 


Reed Alpert | Corporate & Investment Bank | Market Data Services | J.P. Morgan | 4 Metrotech Center, 23rd Floor, Brooklyn, NY 11245 | T: 718.242.5198  | M: 917.414.4613 | reed.alpert@...

Alternate Contact:  CIB Market Data Services Engineers | CIB_Market_Data_Services_Engineers@...

 

 

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