14 Oct
2016
14 Oct
'16
9:32 p.m.
app_perl module has an option to reset the interpreter -- check to see
if that's enabled, it might affect what you do there.
Daniel
On 14/10/16 19:02, Alex Balashov wrote:
Ah, I see.
The motivation for the question was an attempt to troubleshoot why the value of this hash
is occasionally empty.
Every once in a while, it's set to empty and then reloaded from the database (after
x many accesses). The thinking was that perhaps another worker is trying to access this
value at the same time that it was emptied in a different context.
However, if the interpreter instances are per-process, that theory is probably out. Thank
you, Daniel!
On October 14, 2016 12:59:13 PM EDT, Daniel-Constantin Mierla <miconda(a)gmail.com>
wrote:
--
Daniel-Constantin Mierla
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Kamailio Advanced Training, Berlin, Oct 24-26, 2016 - http://www.asipto.com
Hello,
it is a perl interpreter per process, otherwise it will need a
dedicated
process for it with some interprocess communication with the other
worker processes and I haven't seen that in the code, in the few
moments
I was working on this module.
Cheers,
Daniel
On 14/10/16 16:14, Alex Balashov wrote:
--
Daniel-Constantin Mierla
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Kamailio Advanced Training, Berlin, Oct 24-26, 2016 -
http://www.asipto.com
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-- Alex
--
Principal, Evariste Systems LLC (www.evaristesys.com)
Sent from my Google Nexus.
Hi Torrey,
I don't think that's how the app_perl module works. I believe it
spawns a single instance of the interpreter that is shared among the
processes. I could be mistaken, but that's how it looks from the
module code.
On 10/14/2016 03:22 AM, Torrey Searle wrote:
> My experience with app_perl is that global variables are not shared
> between processes. So if you have 10 kamailio processes you would
have
> 10 different %hash with different values. So
it is thread safe, but
> perhaps isn't what you want.
>
> Torrey
>
> On 13 October 2016 at 23:15, Alex Balashov
<abalashov(a)evaristesys.com
> <mailto:abalashov@evaristesys.com>>
wrote:
>
> I meant a global Perl variable -- one that would persist in a
> persistent interpreter. Specifically, a "package variable" of
> this type:
>
> our %hash = ();
>
>
> On 10/13/2016 04:26 PM, Daniel-Constantin Mierla wrote:
>
> Hello,
>
> is it about a global variable defined inside the perl script
or
> you mean
> kamailio.cfg variables? The terminology you used might be
clear
> for Perl
> guys, but as I am not one, I want to clarify it...
>
> As generic remarks -- kamailio is multi-process application,
> so each
> child is a process, not a thread. Each process has its own
> private
> memory space, so a global kamailio.cfg variable such as
> $var(x) is
> defined in each process and each process has access to the
one
> specific
> to it. There are shared memory variables, like $shv(z) that
all
> processes can access and change,
requiring synchronization
to
> avoid races.
>
> Cheers,
> Daniel
>
>
> On 13/10/16 19:13, Alex Balashov wrote:
>
> Hi,
>
> Given the presence of a global (e.g. "our") package
variable
> in an
> embedded Perl script used through app_perl, is there any
> implicit
> thread safety?
>
> That is to say, can a Perl function invoked by one SIP
> worker reset
> the value of a global while another instance of the
function
invoked
by a different SIP worker is accessing it?
And if so, is it safe to use generic perlthr locking to
avoid this?
Thanks!
-- Alex
--
Alex Balashov | Principal | Evariste Systems LLC
Tel: +1-706-510-6800 (direct) / +1-800-250-5920 (toll-free)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/
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