Re: Corosync 1.3.x/1.4.x: Random redundant ring instabilities
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We can reproduce the first one easily, and this is why I have been able to make a patch for it. However, https://bugzilla.redhat.com/show_bug.cgi?id=820821 is really hard for us to reproduce (or was ... I just saw your update on the bug report :). By really hard I mean that it occurred only on some of our customers' clusters and it is very rare. In other words, it happens at the worst place possible to debug it. This is why I wanted to use CTS to try to reproduce it.
Now that you have found what is causing the bug #820821, I will be able to make sure easily that we are affected by the very same bug. I'll also be able to test your patch :). I'll keep you updated on the results.
Thank you very much for your work.By the way, I still think updating cts/README would be a good idea. For instance, it would allow me to run these tests on FreeBSD and our systems each time we switch to a new version a Corosync.
On 11.06.2012 09:35, Jan Friesse wrote:
Jerome,you really don't need to install CTS to reproduce BZ#820821, because as you wrote, you are able to reproduce by yourself. So if you can add information to that BZ HOW you would able to reproduce it and/or find out different (maybe more reliable reproducer) it would be great.Honza Jerome FLESCH napsal(a):I've had a look at the bug report https://bugzilla.redhat.com/show_bug.cgi?id=820821 . If I understand it correctly, the only known way to reproduce this bug at the moment is to run CTS until it fails ? This bug is a major issue for us, so I would like to try to reproduce it on my end. However I haven't been able to run CTS yet. I've read https://github.com/corosync/corosync/tree/master/cts#readme but it seems obsolete (I can't find corolab.py anywhere in the repo). Also CTS seems to be tied in some way to Pacemaker ?Could you please give some short instructions on how to run CTS, or better yet, update cts/README ?----- Mail original ----- De: "Jan Friesse"<jfriesse@xxxxxxxxxx> À: "Jerome FLESCH"<jerome.flesch@xxxxxxxxxx>Cc: discuss@xxxxxxxxxxxx, "Christophe CARRE"<christophe.carre@xxxxxxxxxx>, "Thomas MONTAGNE"<thomas.montagne@xxxxxxxxxx>, "nicolas"<nicolas.dumont@xxxxxxxxxx>Envoyé: Jeudi 7 Juin 2012 11:04:04Objet: Re: Corosync 1.3.x/1.4.x: Random redundant ring instabilitiesJerome, I believe first and second behavior is same as described in https://bugzilla.redhat.com/show_bug.cgi?id=820821 by Andrew. I'm not yet entirely sure WHY is happening. Third one, flushing, is very important. Without flush, buffer may start to overload and it causes really bad behavior (there was BZ with this problem). I would like Steve to review your patch, but for me it looks like ok. Regards, Honza Jerome FLESCH napsal(a):Hello,When upgrading from Corosync 1.2.8 to Corosync 1.4.2/1.4.3, some nasty bugs appeared on our clusters. I observed the following bad behaviors: 1) A process connected to Corosync with CPG wasn't correctly informed that there are other processes connected on other processors. It also didn't get their messages 2) A process sending messages with CPG never received copies of its messages3) 1 ring out of 2 went up/down quite oftenThe behaviors 1 and 2 are very hard for us to reproduce, but we are able to get the behavior 3 quite easily.The simplest setup we found to get it is the following:- 2 VirtualBox VMs, connected by 2 network interfaces (vboxnet0, vboxnet1 ; one for each ring)- OS: Linux (Debian stable)- On one of the VMs, a test program sending some CPG messages (see the script "test_corosync.sh" joined to this mail for example)Here are the Corosync logs we get when we do this setup:Jun 06 16:23:40 corosync [TOTEM ] A processor joined or left the membership and a new membership was formed. Jun 06 16:23:40 corosync [CPG ] chosen downlist: sender r(0) ip(192.168.56.104) r(1) ip(192.168.57.104) ; members(old:1 left:0) Jun 06 16:23:40 corosync [MAIN ] Completed service synchronization, ready to provide service. Jun 06 16:24:37 corosync [TOTEM ] Marking ringid 1 interface 192.168.57.105 FAULTYJun 06 16:24:38 corosync [TOTEM ] Automatically recovered ring 1Jun 06 16:25:33 corosync [TOTEM ] Marking ringid 1 interface 192.168.57.105 FAULTYJun 06 16:25:34 corosync [TOTEM ] Automatically recovered ring 1Jun 06 16:26:35 corosync [TOTEM ] Marking ringid 1 interface 192.168.57.105 FAULTYJun 06 16:26:36 corosync [TOTEM ] Automatically recovered ring 1 (...)The second ring goes down about every 2 minutes and automatically back up right after.We spent some times looking for the commit that introduced this bug, and it appears it's due the following one:Corosync 1.3.3 -> 1.3.4: e27a58d93d0d3795beb550f87b660c9c04f11386 Corosync 1.4.1 -> 1.4.2: be608c050247e5f9c8266b8a0f9803cc0a3dc881 Commit message: Ignore memb_join messages during flush operationsI had a look at this commit, and it seems to me it's dropping too many packets: Because of this commit, while totemrrp_recv_flush() is called, Corosync drops memb_join packets, but also ORF tokens. In the end, it seems that sometimes, we drop so many of them that Corosync marks the ring as faulty.To fix that, I've made the patch joined to this mail (corosync-fix-token-drop.patch).However I wonder why this packet dropping is done at such a low layer. Wouldn't it be more appropriate to do it in totemsrp.c ? Moreover, it seems to me that totemrrp_recv_flush() is called every times Corosync get an ORF token (in message_handler_orf_token()). It seems weird to me because the commit message says the packets should only be dropped when we are in gather state to avoid switching suddenly to recovery state.Also, could you tell me if this packet dropping could explain the 2 other behaviors I observed ?Thanks in advance, Regards, _______________________________________________ discuss mailing list discuss@xxxxxxxxxxxx http://lists.corosync.org/mailman/listinfo/discuss
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