Errors found in tcb queue.
Posted in 2020
Jacob Salomon got 'Errors found in tcb queue' from onstat -g bth on 12.10.FC12 and feared corruption. Art Kagel and Paul Watson said the message means structures changed too fast for onstat to follow, so retry, possibly on a quieter system, or hang the engine and take onstat -o. Jacob accepted that no corruption was likely.
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Topics: Versions, Editions & End-of-Life
Hi Folks.
This looks like corruption in the internal tcb structures:
$ onstat -g bth
IBM Informix Dynamic Server Version 12.10.FC12 -- On-Line (Prim) -- Up 5 days 07:57:11 -- 186675748 KbytesThis command attempts to identify any blocking threads.
Errors found in tcb queue.
May be caused by changing data structures.
What does even mean? If some internal queue or structure is corrupt does that mean a crash is imminent? Well, if it is, it's been imminent for about 4 hours already. So I don't think anything serious is about to happen but it does kinda get in the way of a writing a new scripts (w/o SQL anyway.)
How would I go about investigating the cause of this message?
Thanks.
------------------------------
Jacob Salomon
---
Nobody goes there anymore, it's too crowded. --Attr: Yogi Berra
------------------------------
#Informix
Jacob:
The important part of the message is the note that the error "
May be caused by changing data structures." It most likely means that the memory structures were changing too quickly for onstat to follow the memory link change before it changes causing the search to go off into Never-Never land or begin to cycle because of sessions joining and exiting.
Try again at a quieter time is the usual solution, though in this case, since you are attempting to track a live session, that's not practical. You could just try again and hope to get the report completed before the structures change too much.
Art
Art S. Kagel, President and Principal Consultant
ASK Database Management
www.askdbmgt.com
Blog:
http://informix-myview.blogspot.com/
Disclaimer: Please keep in mind that my own opinions are my own opinions and do not reflect on the IIUG, nor any other organization with which I am associated either explicitly, implicitly, or by inference. Neither do those opinions reflect those of other individuals affiliated with any entity with which I am affiliated nor those of the entities themselves.
changing data structures is (probably) the key. Try again but on a very
busy system you might still get it.
Try hanging the engine and grabbing an onstat -o AFAIK a hung system
shouldn't see these, but in prod ........
> Hi Folks.
>
> This looks like corruption in the internal tcb structures:
> $ onstat -g bth>
> IBM Informix Dynamic Server Version 12.10.FC12 -- On-Line (Prim) -- Up 5
> days 07:57:11 -- 186675748 Kbytes>
> This command attempts to identify any blocking threads.
> Errors found in tcb queue.
> May be caused by changing data structures.
>
> What does even mean? If some internal queue or structure is corrupt does
> that mean a crash is imminent? Well, if it is, it's been imminent for
> about 4 hours already. So I don't think anything serious is about to
> happen but it does kinda get in the way of a writing a new scripts (w/o
> SQL anyway.)
>
> How would I go about investigating the cause of this message?
>
> Thanks.
>
> ------------------------------
> Jacob Salomon
> ---
> Nobody goes there anymore, it's too crowded. --Attr: Yogi Berra
> ------------------------------
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Art and Paul. Thanks for the reassurance that the structures are [probably] not corrupted. I suppose a more reassuring message might be helpful, like "Structures changing to rapidly to obtain a consistent result". But this will have to do for now. Thanks! ------------------------------ Jacob Salomon --- Nobody goes there anymore, it's too crowded. --Attr: Yogi Berra ------------------------------
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