It seems to me that we're allocating shared memory for SLRU lwlocks twice,
unless I'm missing something.
I think you are right.

Did you check previous versions? i.e. should it be applyed to previous branches?? I suppose yes, to minimize code difference.

Also I'd like an idea to add Assert(offset <= SimpleLruShmemSize(nslots, nlsns)) at the end of SimpleLruInit()


SimpleLruShmemSize() calculates total SLRU shared memory size including lwlocks
size.

SimpleLruInit() starts with line

shared = (SlruShared) ShmemInitStruct(name,
                                      SimpleLruShmemSize(nslots, nlsns),
                                      &found);

which allocates SLRU shared memory (LWLocks size is included because
SimpleLruShmemSize() is used for size computation).

Following line allocates shared memory for LWLocks again:
shared->buffer_locks = (LWLockPadded *) ShmemAlloc(sizeof(LWLockPadded) * 
nslots);

Attached patch fixes that by removing extra ShmemAlloc for SLRU.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company




--
Teodor Sigaev                                   E-mail: teo...@sigaev.ru
                                                   WWW: http://www.sigaev.ru/


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