Hi Katia S:
I have been using multiple threads where each thread starts a client and
maintains a single session. I am using this for Informs as opposed to the
get/set.
In all the usage documentation it was found that we need to perform
init_snmp("PROGNAME"), once for all threads. Each thread creates a
session using the single session APIs. I would also like to know if the
init_snmp needs to be done per session as stated by you below. If
init_snmp is done once per process and snmp_sess_open is used to create a
valid snmp session within each thread context then multiple threads
maintaining one session per thread works as expected.
Thanks
Mukund
On Fri, Sep 7, 2012 at 5:15 AM, Katia Sarsempagieva <
kat...@iit.demokritos.gr> wrote:
> **
> Greetings everyone!
> I have already and extensively searched answers for the particular
> problem,
> but I failed to find any. So, if this topic has already been answered, I
> apologize.
>
> Problem Context:
> ---------------------------------
> Let's say I have a MIB that contains a table.
> And I have written a multi-threaded Net-SNMP Client application that reads
> and writes
> to the mentioned MIB.
> Each thread writes on its own Index. For example, only one thread will
> write and read the
> row with Index = 1 (myTable.1), so I do not have to lock any rows or
> tables to add thread protection.
> (The second thread will work on Index = 2 (myTable.2), and so on and so
> forth).
>
> Each thread creates its own SNMP Session. It initializes a session with
> the name "ThreadID=Index",
> where "Index" is the Index of the row the particular thread will play
> with.
> (Example: init_snmp("ThreadIndex=1"); )
> Later, it creates a Session and opens it.
> With the open Session, it uses get and set code to play with the MIB and
> at the end it closes the Session.
>
>
> Problem Question:
> ---------------------------------
> Are the mentioned assumptions even correct?
> Is it possible to have a multi-threaded Net-SNMP Client with one session
> per thread?
> If yes, what are the rules that have to be followed in order to avoid
> SegFaults, that are occurring at my program
> at random times (usually when the client changes to another thread or when
> a thread gets a "NULL" response via
> a snmp_synch_response function)?
>
> Environment:
> ---------------------------------
> Just in case, I post the environment parameters in which I am working.
>
> OS: Debian, Linux
> Net-SNMP Version: 5.7.1 (source code installation)
> Threading Lib: pthread.h
> Net-SNMP Client and Server, both on Localhost
> Programming Language: C
>
> Any insight on the aforementioned problem and any useful advice will be
> greatly appreciated!
> Thank you very much in advance!
>
> Best regards,
>
> --
> *Katia Sarsempagieva*
>
> * Research Assistant
> Media Network Laboratory
> Institute of Information and Telecommunications
> NCSR Demokritos
> *
>
>
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