Hi,

I would like to go back to what I mentioned in an earlier comment about running 
imcn only on the active node. Imcn is doing nothing on any other node than the 
active only wasting resources.
I think this is still applicable also if using RDE callback and rda_get_role(). 
The current implementation of imcn does not guarantee that IMM events are not 
lost (missing notifications from imcn) e.g. during HA state change. To handle 
this the notification for reporting possible loss of information exist. If we 
don’t want to enhance imcn by removing this limitation, there is actually no 
need to run imcn on any node except the active. This means that it is ok to 
exit imcn when a state change happens and start imcn on the new active only. In 
order to make sure that imcn is terminated as soon as possible a rde thread in 
the imcn process could handle rde callbacks and immediately exit the imcn 
process when a state change is requested. This should prevent the no longer 
active imcn from sending any notification after the new imcn has been started 
and also see to that imcn is not running on the no longer active node.

Thanks
Lennart



---

** [tickets:#2219] ntfd: circular dependency with osafntfimcnd**

**Status:** assigned
**Milestone:** 5.0.2
**Created:** Thu Dec 08, 2016 05:14 AM UTC by Gary Lee
**Last Updated:** Thu Dec 15, 2016 11:41 AM UTC
**Owner:** Praveen


A circular dependency can be seen when performing a si-swap of 
safSi=SC-2N,safApp=OpenSAF:

1. Active NTFD is trying to sync with Standby using MBC
2. Standby NTFD is the process of terminating its local osafntfimcnd. It is 
stuck in timedwait_imcn_exit() and cannot reply to the Active.
3. osafntfimcnd [on standby] is trying to send a notfication to Active NTFD

So we have (1) depending on (2) depending on (3) depending on (1)

This results in a temporary deadlock that dramatically slows down NTFD's 
ability to process its main dispatch loop. The deadlock only lasts for approx. 
1 second, when mbcsv_mds_send_msg() times out. But since there could be lots of 
MBC messages to send, sometimes osafntfimcnd is killed with SIGABRT generating 
a coredump. The si-swap operation will also timeout.

steps to reproduce
- Run loop of ntftest 32
root@SC-1:~# for i in {1..10}; do ntftest 32; done
- On another terminal, keep swapping 2N Opensaf SI, got coredump after couples 
of swaps
root@SC-1:~# amf-adm si-swap safSi=SC-2N,safApp=OpenSAF
...
root@SC-1:~# amf-adm si-swap safSi=SC-2N,safApp=OpenSAF

~~~
SC-2 (active)

There are a lot of send failures. Each taking approx. 1 second to timeout. 
During these 1 second timeouts, NTFD cannot process the main dispatch loop.
    
    Dec  7 11:01:37.531772 osafntfd [452:mbcsv_mds.c:0185] >> 
mbcsv_mds_send_msg: sending to vdest:e
    Dec  7 11:01:37.531781 osafntfd [452:mbcsv_mds.c:0209] TR send type 
MDS_SENDTYPE_REDRSP:
    Dec  7 11:01:38.537307 osafntfd [452:mbcsv_mds.c:0247] << 
mbcsv_mds_send_msg: failure
    Dec  7 11:01:38.537758 osafntfd [452:mbcsv_mds.c:0185] >> 
mbcsv_mds_send_msg: sending to vdest:e
    Dec  7 11:01:38.537766 osafntfd [452:mbcsv_mds.c:0209] TR send type 
MDS_SENDTYPE_REDRSP:
    Dec  7 11:01:39.543180 osafntfd [452:mbcsv_mds.c:0247] << 
mbcsv_mds_send_msg: failure
    Dec  7 11:01:39.543695 osafntfd [452:mbcsv_mds.c:0185] >> 
mbcsv_mds_send_msg: sending to vdest:e
    Dec  7 11:01:39.543698 osafntfd [452:mbcsv_mds.c:0209] TR send type 
MDS_SENDTYPE_REDRSP:
    Dec  7 11:01:40.545252 osafntfd [452:mbcsv_mds.c:0247] << 
mbcsv_mds_send_msg: failure
    Dec  7 11:01:40.545719 osafntfd [452:mbcsv_mds.c:0185] >> 
mbcsv_mds_send_msg: sending to vdest:e
    Dec  7 11:01:40.545726 osafntfd [452:mbcsv_mds.c:0209] TR send type 
MDS_SENDTYPE_REDRSP:
    Dec  7 11:01:41.551328 osafntfd [452:mbcsv_mds.c:0247] << 
mbcsv_mds_send_msg: failure
    Dec  7 11:01:41.551971 osafntfd [452:mbcsv_mds.c:0185] >> 
mbcsv_mds_send_msg: sending to vdest:e
    Dec  7 11:01:41.551979 osafntfd [452:mbcsv_mds.c:0209] TR send type 
MDS_SENDTYPE_REDRSP:
    Dec  7 11:01:42.557594 osafntfd [452:mbcsv_mds.c:0247] << 
mbcsv_mds_send_msg: failure
    Dec  7 11:01:42.558171 osafntfd [452:mbcsv_mds.c:0185] >> 
mbcsv_mds_send_msg: sending to vdest:e
    Dec  7 11:01:42.558179 osafntfd [452:mbcsv_mds.c:0209] TR send type 
MDS_SENDTYPE_REDRSP:
    Dec  7 11:01:43.564051 osafntfd [452:mbcsv_mds.c:0247] << 
mbcsv_mds_send_msg: failure
    Dec  7 11:01:43.564874 osafntfd [452:mbcsv_mds.c:0185] >> 
mbcsv_mds_send_msg: sending to vdest:e
    Dec  7 11:01:43.564883 osafntfd [452:mbcsv_mds.c:0209] TR send type 
MDS_SENDTYPE_REDRSP:
    Dec  7 11:01:44.572407 osafntfd [452:mbcsv_mds.c:0247] << 
mbcsv_mds_send_msg: failure
    Dec  7 11:01:44.573262 osafntfd [452:mbcsv_mds.c:0185] >> 
mbcsv_mds_send_msg: sending to vdest:e
    Dec  7 11:01:44.573271 osafntfd [452:mbcsv_mds.c:0209] TR send type 
MDS_SENDTYPE_REDRSP:
    Dec  7 11:01:45.575091 osafntfd [452:mbcsv_mds.c:0247] << 
mbcsv_mds_send_msg: failure
    Dec  7 11:01:47.083548 osafntfd [452:mbcsv_mds.c:0185] >> 
mbcsv_mds_send_msg: sending to vdest:e
    
~~~


~~~
SC-1 (standby)

NTFD is trying to terminate osafntfimcnd. While it is doing that, it cannot 
reply to NTFD on SC-2. Meanwhile, osafntfimcnd is sending NTF notifications to 
NTFD on SC-1.
    
    Dec  7 11:01:35.453151 osafntfd [464:ntfs_imcnutil.c:0316] TR 
handle_state_ntfimcn: Terminating osafntfimcnd process
    Dec  7 11:01:45.474313 osafntfd [464:ntfs_imcnutil.c:0124] TR   Termination 
timeout
    Dec  7 11:01:45.474375 osafntfd [464:ntfs_imcnutil.c:0130] << 
wait_imcnproc_termination: rc = -1, retry_cnt = 101
    Dec  7 11:01:45.474387 osafntfd [464:ntfs_imcnutil.c:0168] TR   Normal 
termination failed. Escalate to abort
    Dec  7 11:01:45.574703 osafntfd [464:ntfs_imcnutil.c:0172] TR   Imcn 
successfully aborted
    Dec  7 11:01:45.574712 osafntfd [464:ntfs_imcnutil.c:0187] << 
timedwait_imcn_exit    
~~~



---

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