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Informix - Problem description

Problem IT33316 Status: Closed

SLOW LOG TRANSFER FROM PRIMARY TO RSS NODE DUE TO BAD SMX PIPE

product:
INFORMIX SERVER / 5725A3900 / C10 - IDS 12.10
Problem description:
There appears to be a problem that might occur when a primary
and rss node connect.  This can lead to 1 or more bad smx pipes
that can't then be used to transfer data between servers.  When
this happens since pipes are picked randomly, if the bad pipe is
picked there is an approximate 30 second delay before the server
picks a new pipe to try and send data.  This will greatly impact
performance.

In onstat -g smx output, a bad pipe would show up in the output
for the node, but will have no data transmitted on it.  So it
would look something like this:

  Peer server name: Rssnode1
  SMX connection address: 0x700000116143480
  Encryption status: Disabled
  Total bytes sent: 0
  Total bytes received: 0
  Total buffers sent: 0
  Total buffers received: 0
  Total write calls: 0
  Total read calls: 0
  Total retries for write call: 0
  Data compression level: 0
  Data sent: compressed 0 bytes by  0%
  Data received: compressed 0 bytes by  0%
  SMX connection address: 0x70000090f1f3a30
  Encryption status: Disabled
  Total bytes sent: 7110578
  Total bytes received: 76965
  Total buffers sent: 11990
  Total buffers received: 4853
  Total write calls: 3545
  Total read calls: 4853
  Total retries for write call: 0
  Data compression level: 1
  Data sent: compressed 37158220 bytes by 80%
  Data received: compressed 92260 bytes by 16%

So the above -g smx output the 1st SMX connection is bad and not
being used while the 2nd appears to be functioning.

Additionally, smx pipe connections between servers involve
spawning multiple threads, a smxsnd , smxrcv
, and smxRecvSnd.  For the bad pipe, the setup
hasn't finished and in this case, the onstat -g cpu/-g ath
output you would only see a smxsnd , smx, and
smxRecvSnd thread.  The smx thread hasn't renamed itself to
smxrcv  yet.  Those threads would have the following
stacks:

Stack for thread: 370 smxsnd 

0x0000000100062b94 (oninit)yield_processor_mvp
0x000000010006e25c (oninit)mt_wait
0x000000010067aba0 (oninit)smx_send_thread
0x0000000100fea500 (oninit)th_init_initgls
0x00000001017c2860 (oninit)startup

smxRecvSnd

0x0000000100062b94 (oninit)yield_processor_mvp
0x0000000100069b6c (oninit)mt_yield
0x00000001002b6b8c (oninit)cdrTimerWait
0x000000010067c358 (oninit)smx_send_from_recv_thread
0x0000000100fea500 (oninit)th_init_initgls
0x00000001017c2860 (oninit)startup

Stack for thread: 363 smx

0x0000000100062b94 (oninit)yield_processor_mvp
0x000000010006e25c (oninit)mt_wait
0x0000000100680964 (oninit)smx_thread
0x0000000100c62718 (oninit)listen_verify
0x0000000100c6133c (oninit)spawn_thread
0x0000000100fea500 (oninit)th_init_initgls
0x00000001017c2860 (oninit)startup

Thread states in onstat -g ath:

 363      700000116120028  70000011356f728  1    cond wait  smx
pipe1   11cpu         smx
 369      7000001161ff850  700000113572b78  1    sleeping secs:
1       31cpu         smxRecvSnd
 370      700000114a56148  700000113573430  3    cond wait  smx
pipe1   11cpu         smxsnd hdr_ausp3

When examining the condition "smx pipe1" (there can be multiple
conditions with the same name so have to use the thread ids of
the waiters to find the correct one)

Conditions with waiters:
cid      addr             name               waiter   waittime
...
1568     7000001161e6648  smx pipe1          363      1048602
                                     370      1048602
                                     321      1048602

We also see a different thread also waiting on this "smx pipe1"
condtion, thread 321.  If we look at what that thread is and
it's stack we see the following:

Stack for thread: 321 Notification

0x0000000100062b94 (oninit)yield_processor_mvp
0x000000010006e25c (oninit)mt_wait
0x0000000100674524 (oninit)smx_connect
0x00000001006b0de8 (oninit)cloneWakeupRSSRetry
0x00000001002bbf80 (oninit)cdrExstmt
0x00000001006b0fe0 (oninit)cloneRSSRetry
0x00000001006927b0 (oninit)cloneNotificationThread
0x0000000100fea500 (oninit)th_init_initgls
0x00000001017c2860 (oninit)startup

The presence of this "Notification" thread is likely key in
trying to identify hitting this problem as well.
Problem Summary:
****************************************************************
* USERS AFFECTED:                                              *
* Users of Informix Server prior to 12.10.xC15 and 14.10.xC5.  *
****************************************************************
* PROBLEM DESCRIPTION:                                         *
* See Error Description                                        *
****************************************************************
* RECOMMENDATION:                                              *
* Upgrade to Informix Server 12.10.xC15 (when available) or    *
* 14.10.xC5.                                                   *
****************************************************************
Local Fix:
Solution
Workaround
not known / see Local fix
Timestamps
Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :
24.06.2020
06.01.2021
06.01.2021
Problem solved at the following versions (IBM BugInfos)
Problem solved according to the fixlist(s) of the following version(s)
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