Assertion in pgstat_assoc_relation() fails intermittently

Hi,

I recently observed an assertion failure [1] a few times on my dev
setup during initdb. The code was built with --enable-debug
--enable-cassert CFLAGS="-ggdb3 -O0". The assertion was gone after I
did make distclean and built the source code again. It looks like the
same relation (pg_type [2]) is linked to multiple relcache entries.
I'm not sure if anyone else has seen this, but thought of reporting it
here. Note that I'm not seeing this issue any more.

[1]
running bootstrap script ... TRAP: failed
Assert("rel->pgstat_info->relation == NULL"), File:
"pgstat_relation.c", Line: 143, PID: 837245
/home/ubuntu/postgres/inst/bin/postgres(ExceptionalCondition+0xbb)[0x55d98ff6abc4]
/home/ubuntu/postgres/inst/bin/postgres(pgstat_assoc_relation+0xcd)[0x55d98fdb3db7]
/home/ubuntu/postgres/inst/bin/postgres(+0x1326f5)[0x55d98f8576f5]
/home/ubuntu/postgres/inst/bin/postgres(heap_beginscan+0x17a)[0x55d98f8586b5]
/home/ubuntu/postgres/inst/bin/postgres(table_beginscan_catalog+0x6e)[0x55d98f8c4cf3]
/home/ubuntu/postgres/inst/bin/postgres(+0x1f3d29)[0x55d98f918d29]
/home/ubuntu/postgres/inst/bin/postgres(+0x1f4031)[0x55d98f919031]
/home/ubuntu/postgres/inst/bin/postgres(DefineAttr+0x216)[0x55d98f918375]
/home/ubuntu/postgres/inst/bin/postgres(boot_yyparse+0x115c)[0x55d98f91499c]
/home/ubuntu/postgres/inst/bin/postgres(BootstrapModeMain+0x5cb)[0x55d98f917cda]
/home/ubuntu/postgres/inst/bin/postgres(main+0x2f3)[0x55d98fb63738]
/lib/x86_64-linux-gnu/libc.so.6(+0x29d90)[0x7faac24d8d90]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x80)[0x7faac24d8e40]
/home/ubuntu/postgres/inst/bin/postgres(_start+0x25)[0x55d98f7f2045]
Aborted (core dumped)
child process exited with exit code 134
initdb: removing data directory "data"

#3 0x0000562d92043da9 in pgstat_assoc_relation (rel=0x562d93dd9bc8)
at pgstat_relation.c:148
#4 0x0000562d91ae76f5 in initscan (scan=0x562d93e047f8, key=0x0,
keep_startblock=false) at heapam.c:344
#5 0x0000562d91ae86b5 in heap_beginscan (relation=0x562d93dd9bc8,
snapshot=0x562d93dfe3f8, nkeys=0, key=0x0,
parallel_scan=0x0, flags=961) at heapam.c:1017
#6 0x0000562d91b54cf3 in table_beginscan_catalog
(relation=0x562d93dd9bc8, nkeys=0, key=0x0) at tableam.c:119
#7 0x0000562d91ba8d29 in populate_typ_list () at bootstrap.c:719
#8 0x0000562d91ba9031 in gettype (type=0x562d93e047d8 "anyarray") at
bootstrap.c:801
#9 0x0000562d91ba8375 in DefineAttr (name=0x562d93e047b8
"attmissingval", type=0x562d93e047d8 "anyarray", attnum=25,
nullness=1) at bootstrap.c:521
#10 0x0000562d91ba499c in boot_yyparse () at
/home/ubuntu/postgres/src/backend/bootstrap/bootparse.y:438
#11 0x0000562d91ba7cda in BootstrapModeMain (argc=6,
argv=0x562d93d4a1d8, check_only=false) at bootstrap.c:370
#12 0x0000562d91df3738 in main (argc=7, argv=0x562d93d4a1d0) at main.c:189

[2]
(gdb) p *relation
$2 = {rd_locator = {spcOid = 1663, dbOid = 1, relNumber = 1247},
rd_smgr = 0x562d93e090a8, rd_refcnt = 3, rd_backend = -1,
rd_islocaltemp = false,
rd_isnailed = true, rd_isvalid = true, rd_indexvalid = false,
rd_statvalid = false, rd_createSubid = 1, rd_newRelfilelocatorSubid =
0,
rd_firstRelfilelocatorSubid = 0, rd_droppedSubid = 0, rd_rel =
0x562d93ddae18, rd_att = 0x562d93dd9dd8, rd_id = 1247, rd_lockInfo =
{lockRelId = {
relId = 1247, dbId = 1}}, rd_rules = 0x0, rd_rulescxt = 0x0,
trigdesc = 0x0, rd_rsdesc = 0x0, rd_fkeylist = 0x0, rd_fkeyvalid =
false, rd_partkey = 0x0,
rd_partkeycxt = 0x0, rd_partdesc = 0x0, rd_pdcxt = 0x0,
rd_partdesc_nodetached = 0x0, rd_pddcxt = 0x0,
rd_partdesc_nodetached_xmin = 0, rd_partcheck = 0x0,
rd_partcheckvalid = false, rd_partcheckcxt = 0x0, rd_indexlist =
0x0, rd_pkindex = 0, rd_replidindex = 0, rd_statlist = 0x0,
rd_attrsvalid = false,
rd_keyattr = 0x0, rd_pkattr = 0x0, rd_idattr = 0x0,
rd_hotblockingattr = 0x0, rd_summarizedattr = 0x0, rd_pubdesc = 0x0,
rd_options = 0x0, rd_amhandler = 3,
rd_tableam = 0x562d92582040 <heapam_methods>, rd_index = 0x0,
rd_indextuple = 0x0, rd_indexcxt = 0x0, rd_indam = 0x0, rd_opfamily =
0x0, rd_opcintype = 0x0,
rd_support = 0x0, rd_supportinfo = 0x0, rd_indoption = 0x0,
rd_indexprs = 0x0, rd_indpred = 0x0, rd_exclops = 0x0, rd_exclprocs =
0x0, rd_exclstrats = 0x0,
rd_indcollation = 0x0, rd_opcoptions = 0x0, rd_amcache = 0x0,
rd_fdwroutine = 0x0, rd_toastoid = 0, pgstat_enabled = true,
pgstat_info = 0x562d93d79fb8}
(gdb) p *relation->rd_rel
$3 = {oid = 0, relname = {data = "pg_type", '\000' <repeats 56
times>}, relnamespace = 11, reltype = 0, reloftype = 0, relowner = 10,
relam = 2,
relfilenode = 0, reltablespace = 0, relpages = 0, reltuples = 0,
relallvisible = 0, reltoastrelid = 0, relhasindex = false, relisshared
= false,
relpersistence = 112 'p', relkind = 114 'r', relnatts = 32,
relchecks = 0, relhasrules = false, relhastriggers = false,
relhassubclass = false,
relrowsecurity = false, relforcerowsecurity = false, relispopulated
= true, relreplident = 110 'n', relispartition = false, relrewrite =
0, relfrozenxid = 0,
relminmxid = 0}
(gdb)

--
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com