Re: BUG #16925: ERROR: invalid DSA memory alloc request size 1073741824 CONTEXT: parallel worker

On Sat, Mar 13, 2021 at 11:59 PM Thomas Munro <thomas.munro@gmail.com> wrote:
> > > 2021-03-12 19:45:37.352 CET [316243] ERROR:  XX000: invalid DSA memory alloc
> > > request size 1073741824

After an off-list exchange with Karen and colleague who ran this with
the ERROR changed to a PANIC and examined the smoldering core, the
problem turns out to be a failure to keep the hashtable bucket array
<= MaxAllocSize in one code path.  Although commit 86a2218e fixed
another version of that problem a while ago, it can still be
exceeded... by one byte... when we expand from one batch to many.
Will propose a fix.

                    dbuckets = Min(dbuckets,
                                   MaxAllocSize / sizeof(dsa_pointer_atomic));
                    new_nbuckets = (int) dbuckets;
                    new_nbuckets = Max(new_nbuckets, 1024);
                    new_nbuckets = 1 << my_log2(new_nbuckets);