Re: BUG #17441: shm_mq receive less data than the sender sends

On Sun, Mar 20, 2022 at 9:20 PM PG Bug reporting form
<noreply@postgresql.org> wrote:
>
> The following bug has been logged on the website:
>
> Bug reference:      17441
> Logged by:          ytf
> Email address:      fft_665665@163.com
> PostgreSQL version: 10.17
> Operating system:   centos
> Description:
>
> Dears,
>
> I launch one dynamic worker as the sender, use shm_mq send data to the
> SELECT, which I register a copy hook to receive data from sender.
> Each data length is 800.
>
> When I set shm_mq SIZE to 16, there is no problem. Only speed is very
> slow.
>
> However, when I set shm_mq Size to 8192 or larger, I meet a problem.
>
> I first receive 800 length data , and after a few times, I only receive 732
> length data.
>
> I registered the shm_mq like following :
> #define QUEUE_SIZE 8192
> mq = shm_mq_create(shm_toc_allocate(pcxt->toc, QUEUE_SIZE), QUEUE_SIZE);
> shm_toc_insert(pcxt->toc, COS_KEY_QUEUE, mq);
> shm_mq_set_receiver(mq, MyProc);

Could you please provide the reproducible steps and codes for the
problem you're facing? That's very helpful to understand and
investigate the problem.

Regards,

-- 
Masahiko Sawada
EDB:  https://www.enterprisedb.com/