On Sat, Feb 8, 2020 at 12:10 AM Andres Freund <and...@anarazel.de> wrote: > > Hi, > > On 2020-02-04 10:15:01 +0530, Kuntal Ghosh wrote: > > I performed the same test in pg11 and reproduced the issue on the > > commit prior to a4ccc1cef5a04 (Generational memory allocator). > > > > ulimit -s 1024 > > ulimit -v 300000 > > > > wal_level = logical > > max_replication_slots = 4 > > > > [...] > > > After that, I applied the "Generational memory allocator" patch and > > that solved the issue. From the error message, it is evident that the > > underlying code is trying to allocate a MaxTupleSize memory for each > > tuple. So, I re-introduced the following lines (which are removed by > > a4ccc1cef5a04) on top of the patch: > > > --- a/src/backend/replication/logical/reorderbuffer.c > > +++ b/src/backend/replication/logical/reorderbuffer.c > > @@ -417,6 +417,9 @@ ReorderBufferGetTupleBuf(ReorderBuffer *rb, Size > > tuple_len) > > > > alloc_len = tuple_len + SizeofHeapTupleHeader; > > > > + if (alloc_len < MaxHeapTupleSize) > > + alloc_len = MaxHeapTupleSize; > > Maybe I'm being slow here - but what does this actually prove? Before > the generation contexts were introduced we avoided fragmentation (which > would make things unusably slow) using a a brute force method (namely > forcing all tuple allocations to be of the same/maximum size). >
It seems for this we formed a cache of max_cached_tuplebufs number of objects and we don't need to allocate more than that number of tuples of size MaxHeapTupleSize because we will anyway return that memory to aset.c. -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com
