Thanks Amit for patch. Crash is fixed by this patch.
Thanks and Regards Mahendra Thalor On Sat, Oct 12, 2019, 09:03 Amit Kapila <amit.kapil...@gmail.com> wrote: > On Fri, Oct 11, 2019 at 4:47 PM Mahendra Singh <mahi6...@gmail.com> wrote: > > > > > > I did some analysis and found that we are trying to free some already > freed memory. Or we are freeing palloced memory in vac_update_relstats. > > for (i = 0; i < nindexes; i++) > > { > > if (stats[i] == NULL || stats[i]->estimated_count) > > continue; > > > > /* Update index statistics */ > > vac_update_relstats(Irel[i], > > stats[i]->num_pages, > > stats[i]->num_index_tuples, > > 0, > > false, > > InvalidTransactionId, > > InvalidMultiXactId, > > false); > > pfree(stats[i]); > > } > > > > As my table have 2 indexes, so we have to free both stats. When i = 0, > it is freeing propery but when i = 1, then vac_update_relstats is freeing > memory. > >> > >> (gdb) p *stats[i] > >> $1 = {num_pages = 218, pages_removed = 0, estimated_count = false, > num_index_tuples = 30000, tuples_removed = 30000, pages_deleted = 102, > pages_free = 0} > >> (gdb) p *stats[i] > >> $2 = {num_pages = 0, pages_removed = 65536, estimated_count = false, > num_index_tuples = 0, tuples_removed = 0, pages_deleted = 0, pages_free = 0} > >> (gdb) > > > > > > From above data, it looks like, somewhere inside vac_update_relstats, we > are freeing all palloced memory. I don't know, why is it. > > > > I don't think the problem is in vac_update_relstats as we are not even > passing stats to it, so it won't be able to free it. I think the real > problem is in the way we copy the stats from shared memory to local > memory in the function end_parallel_vacuum(). Basically, it allocates > the memory for all the index stats together and then in function > update_index_statistics, it is trying to free memory of individual > array elements, that won't work. I have tried to fix the allocation > in end_parallel_vacuum, see if this fixes the problem for you. You > need to apply the attached patch atop > v28-0001-Add-parallel-option-to-VACUUM-command posted above by > Sawada-San. > > -- > With Regards, > Amit Kapila. > EnterpriseDB: http://www.enterprisedb.com >