[NOVICE] seg fault on dsm_create call

[Max Fomichev]

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



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[Andrej]

On 29 June 2016 at 00:47, Max Fomichev <max.fo...@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