Subject Re: lock denied...
Author
---In firebird-support@yahoogroups.com, <ehmmm.firebird@...> wrote :

> last weekend we switched from FB 2.5.x to  FB V3.0.3.32796
>
> We have couple databases, the biggest has around 12 GB.
> About 100-200 clients are connecting to this DB via PHP approximately twice per minute to see some data.
> Some services on server are writing data into this DB.
> We are using FB in SuperClassic mode, because some services are written in C and compiled via gpre/gcc.

  Hmm... i see no relation between such services and requirement to use SuperClassic.
–°ould you try Super mode ? SuperClassic in FB3 is legacy and not recommended mode.


> In firebird log I can see messages like this:
>
> z3  Sun Dec  3 01:43:15 2017
>         Database: /opt/firebird/security3.fdb
>         page 0, page type 1 lock denied (216)
...
> Could you please explain me, what do this messages mean?

  It looks like bug due to race condition when lock manager initialized shared memory while another
instance (attachment) is deinitialized it (it is simplified and far from exact description). It could be
something else - i need to reproduce the issue to make correct conclusion.


> How can I avoid them?

  Try to lower load on lock manager. Switch to Super, or try to increase linger on security3.fdb
(it is 60 sec by default).

> What shall I look at?

  If there was coredump produced by crash, you may provide us with backtraces of all stacks.

Regards,
Vlad