When parallel degree is set to very high say 70000, there is a segmentation
fault in parallel code,
and that is because type casting is missing in the code..

Take a look at below test code:

create table abd(n int) with (parallel_degree=70000);
insert into abd values (generate_series(1,1000000)); analyze abd; vacuum
set max_parallel_degree=70000;
explain analyze verbose select * from abd where n<=1;

server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: LOG:  server
process (PID 41906) was terminated by signal 11: Segmentation fault
DETAIL:  Failed process was running: explain analyze verbose select * from
abd where n<=1;

This is crashing because in *ExecParallelSetupTupleQueues *function,

*for* (i = 0; i < pcxt->nworkers; ++i)

* {*

*... *

(Here i is Int but arg to shm_mq_create is Size so when worker is beyond
32767 then 32767*65536 will overflow

the integer boundary, and it will access the illegal memory and will crash
or corrupt some memory. Need to typecast

this will fix

* mq = shm_mq_create(tqueuespace + i * PARALLEL_TUPLE_QUEUE_SIZE,

Below attached patch will fix this issue, Apart from here I have done
typecasting at other places also wherever its needed.
typecasting at other places will fix other issue (ERROR:  requested shared
memory size overflows size_t) also
described in below mail thread


Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com

Attachment: max_parallel_degree_bug.patch
Description: Binary data

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