Thread: seg fault on dsm_create call

Hello.
I'm trying to understand how to work with dynamic shared memory, message
queues and workers.
The problem is I can not initialize a dsm segment -

     void _PG_init() {
         ...
         dsm_segment *seg = dsm_create(32768, 0); // Segmentation fault here
         ...
         BackgroundWorker worker;
         sprintf(worker.bgw_name, "mystem wrapper process");
         worker.bgw_flags = BGWORKER_SHMEM_ACCESS;
         worker.bgw_start_time = BgWorkerStart_RecoveryFinished;
         worker.bgw_restart_time = BGW_NEVER_RESTART;
         worker.bgw_main = mainProc;
         worker.bgw_notify_pid = 0;
         RegisterBackgroundWorker(&worker);
     }

Also I was trying to move dsm_create call to a worker, but with the same
result -

     static void mainProc(Datum) {
         ...
         dsm_segment *seg = dsm_create(32768, 0); // Segmentation fault here
         ...
         pqsignal(SIGTERM, mystemSigterm);
         BackgroundWorkerUnblockSignals();
         ...

What could be a reason and what am I doing wrong?

PS test/modules/test_shm_mq works fine...


--
Best regards,
Max Fomichev

On 29 June 2016 at 00:47, Max Fomichev <max.fomitchev@gmail.com> wrote:
> Hello.
> I'm trying to understand how to work with dynamic shared memory, message
> queues and workers.
> The problem is I can not initialize a dsm segment -
>
>     void _PG_init() {
>         ...
>         dsm_segment *seg = dsm_create(32768, 0); // Segmentation fault here

> Also I was trying to move dsm_create call to a worker, but with the same
> result -
>
>     static void mainProc(Datum) {
>         ...
>         dsm_segment *seg = dsm_create(32768, 0); // Segmentation fault here
>         ...
>         pqsignal(SIGTERM, mystemSigterm);
>         BackgroundWorkerUnblockSignals();
>         ...
>
> What could be a reason and what am I doing wrong?
>
> PS test/modules/test_shm_mq works fine...

I'm no expert in C programming (or postgres, as it were), but
test/modules/test_shm_mq seems to call the function w/ only one
parameter, not two?



> --
> Best regards,
> Max Fomichev


Cheers,
Andrej