Re: [pysnmp-users] cmdgen and SNMPv3

[Ilya E. <il...@gl...>]

Oh, that might be a problem then. I’ve not noticed that advice.

The good thing is that the parsing phase only happens once, then the result is put into $HOME/.pysnmp/mibs/ and only loaded from there.
So you can potentially ‘bootstrap’ all MIBs from a single thread to compile them from ASN.1 source prior to use (there’s also the mibdump command-line tool).
Or have a dedicated thread that only compiles newly required MIBs, other threads never compile anything but only load them up.

I do not see much better solutions since we seem to hit ply’s limitation.

What do you think?

-ilya

> On 15 Nov 2015, at 23:02, Vincent Bernat <be...@lu...> wrote:
> 
> ❦ 15 novembre 2015 17:30 +0100, Vincent Bernat <be...@lu...> :
> 
>> Since many stuff doesn't seem to be thread safe and that SnmpEngine is
>> only parsing MIB stuff to get constant data, this part should be
>> extracted to do it once.
> 
> All the more than starting with PySNMP 4.3, MIBs are parsed/compiled
> with PySMI. I can't say for sure, but is it safe to compile a MIB from
> different threads? It seems that ply is not thread-safe. It is said:
> 
> ╭─────┤ https://github.com/dabeaz/ply/blob/master/ply/yacc.py#L40-L45 ├─────
> │The current implementation is only somewhat object-oriented. The
> │LR parser itself is defined in terms of an object (which allows multiple
> │parsers to co-exist).  However, most of the variables used during table
> │construction are defined in terms of global variables.  Users shouldn't
> │notice unless they are trying to define multiple parsers at the same
> │time using threads (in which case they should have their head
> │examined).
> ╰─────
> —