I have written an extension to manage openstreetmap data. There is a C
function to perform spatial top k query on several tables and return an
array of int8 type as result. The code skeleton of this function is as
follows:
Datum vquery(PG_FUNCTION_ARGS) {
int array_len = PG_GETARG_INT32(0);
long * node_ids;
SPI_connect();
//some code to retrieve data from various tables
// node_ids are allocated and filled up
ArrayType * retarr;
Datum * vals ;
vals = palloc0(array_len * sizeof(long));
// fill the vals up
for (i = 0 ; i < array_len ; i++)
vals[i] = Int64GetDatum((node_ids[i]));
retarr = construct_array(vals, retcnt, INT8OID, sizeof(long), true, 'i');
SPI_finish();
PG_RETURN_ARRAYTYPE_P(retarr);
}
the function runs smoothly when called using relatively small parameter,
such as select(unnest(vquery(1000))) ; but when called with large
parameter, such as select(unnest(vquery(50000))), sometimes it runs
normally, sometimes it runs into "Segmentation Fault" error. the larger the
parameter is, the more likely to run into segmentation fault.
back trace of the process as followings:
Program received signal SIGSEGV, Segmentation fault.
pg_detoast_datum (datum=0x55d4e7e43bc0) at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/utils/fmgr/fmgr.c:2241
2241
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/utils/fmgr/fmgr.c:
No such file or directory.
(gdb) backtrace full
#0 pg_detoast_datum (datum=0x55d4e7e43bc0) at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/utils/fmgr/fmgr.c:2241
No locals.
#1 0x000055d4e485a29f in array_out (fcinfo=0x7ffd0fdb9f30) at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/utils/adt/arrayfuncs.c:958
v = <optimized out>
element_type = <optimized out>
typlen = <optimized out>
typbyval = <optimized out>
typalign = <optimized out>
typdelim = <optimized out>
p = <optimized out>
tmp = <optimized out>
retval = <optimized out>
values = <optimized out>
dims_str =
"\346\263\346U\000\000\000\000f\021\352\312\342\177\000\000
%q\003\000\000\000\000\270\347\026\313\342\177\000\000\000\000\002\000\000\000\000\000\211O\343\312\342\177\000\000(?\a\000\000\000\000\000\371\336\342\312\342\177\000\000\001\000\000\000\000\000\000\000f\021\352\312\342\177\000\000\200\204\004\001\000\000\000\000\270\347\026\313\342\177\000\000\000\000\002\000\000\000\000\000\211O\343\312\342\177\000\000`1\354\352\324U\000\000\371\336\342\312\342\177\000\000\001\000\000\000\000\000\000\000\000\200\355\347\324U\000\000\300;\344\347\324U\000\000\200\373\350\346\324U\000\000\200\204\004\001\000\000\000\000`\347\026\313\342\177\000\000\200;\344\347\324U\000\000\200D\t\000\000\000\000\000\001\000\000\000\000\000\000"
bitmap = <optimized out>
bitmask = <optimized out>
needquotes = <optimized out>
needdims = <optimized out>
nitems = <optimized out>
overall_length = <optimized out>
i = <optimized out>
j = <optimized out>
k = <optimized out>
indx = {125, 0, 1638826752, 1007657037, 266051136, 32765}
ndim = <optimized out>
dims = <optimized out>
lb = <optimized out>
my_extra = <optimized out>
#2 0x000055d4e491bf77 in FunctionCall1Coll
(flinfo=flinfo@entry=0x55d4e6281608,
collation=collation@entry=0, arg1=arg1@entry=94372911922112)
at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/utils/fmgr/fmgr.c:1301
fcinfo = {flinfo = 0x55d4e6281608, context = 0x0, resultinfo = 0x0,
fncollation = 0, isnull = 0 '\000', nargs = 1, arg = {94372911922112, 16,
94372911922112,
94372881863664, 81000, 140612075225152, 140724869504928,
94372856290490, 20, 94372911922112, 140724869504960, 94372855395365, 59362,
59362,
140724869505552, 140611821448277, 140724869505184,
140724869505104, 140724869505056, 25309696688, 4630392398271114606,
4638776743690240000,
4628742354541509959, 4638236535588651008, 140612075225152,
140724869505184, 140724869505264, 140724869505344, 8192, 1340029796386,
94372903805648,
94372905445328, 4412211000755930201, 4295079941117417898,
4212081119735560672, 94372856202527, 2087976960, 94372882833728,
94372882836912, 1,
140724869505296, 4327854021138088704, 3599182594146, 1,
140724869505248, 94372856077425, 1016, 94372882392848, 94372860652912,
140612076116712,
140724869505680, 94372856082219, 94372882407728,
140724869505360, 140724869505343, 3886087214688, 140612076116712,
140724869505344, 140728326873992,
94372882407736, 94372882817344, 94372882817312,
1125891316908032, 0, 94372855675584, 281483566645432, 2, 0, 94372881959504,
0, 1016, 0, 0, 8192,
18446603348840046049, 513, 128, 176, 140724869505568, 16,
459561500672, 2, 0, 511101108336, 0, 140724869505567, 0, 0, 124, 0, 0, 0,
0, 0, 0,
140612046612320, 8192, 1024, 1024, 1072},
argnull = "\000
\000\000\000\000\000\000\300&\343\312\342\177\000\000\220\017(\346\324U\000\000x\201'\346\324U\000\000\320\242\333\017\375\177\000\000\260R\223\344\324U\000\000\060\243\333\017\375\177\000\000\002\000\000\000\000\000\000\000\340\242\333\017\375\177\000\000?:x\344\324U\000\000\000\000\000\000\000\000\000\000\002\000\000\000\000\000\000\000\020\354'\346"}
result = <optimized out>
__func__ = "FunctionCall1Coll"
#3 0x000055d4e491d557 in OutputFunctionCall (flinfo=0x55d4e6281608,
val=94372911922112)
at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/utils/fmgr/fmgr.c:1954
result = <optimized out>
pushed = 0 '\000'
#4 0x000055d4e4635179 in printtup (slot=0x55d4e6280410,
self=0x55d4e627ec10)
at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/access/common/printtup.c:347
outputstr = <optimized out>
thisState = <optimized out>
attr = <optimized out>
typeinfo = <optimized out>
myState = 0x55d4e627ec10
buf = {data = 0x55d4e6288150 "", len = 2, maxlen = 1024, cursor =
68}
natts = 1
---Type <return> to continue, or q <return> to quit---
i = 0
#5 0x000055d4e475c8f7 in ExecutePlan (dest=0x55d4e627ec10,
direction=<optimized out>, numberTuples=0, sendTuples=1 '\001',
operation=CMD_SELECT,
planstate=0x55d4e6280220, estate=0x55d4e6280110) at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/executor/execMain.c:1513
slot = <optimized out>
current_tuple_count = 0
#6 standard_ExecutorRun (queryDesc=0x55d4e61989b0, direction=<optimized
out>, count=0)
at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/executor/execMain.c:318
estate = 0x55d4e6280110
operation = CMD_SELECT
dest = 0x55d4e627ec10
sendTuples = <optimized out>
#7 0x000055d4e484255f in PortalRunSelect (portal=portal@entry=0x55d4e61969a0,
forward=forward@entry=1 '\001', count=0, count@entry=9223372036854775807,
dest=dest@entry=0x55d4e627ec10) at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/tcop/pquery.c:942
queryDesc = 0x55d4e61989b0
direction = <optimized out>
nprocessed = <optimized out>
__func__ = "PortalRunSelect"
#8 0x000055d4e4843b2a in PortalRun (portal=portal@entry=0x55d4e61969a0,
count=count@entry=9223372036854775807, isTopLevel=isTopLevel@entry=1
'\001',
dest=dest@entry=0x55d4e627ec10, altdest=altdest@entry=0x55d4e627ec10,
completionTag=completionTag@entry=0x7ffd0fdba830 "")
at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/tcop/pquery.c:786
save_exception_stack = 0x7ffd0fdba740
save_context_stack = 0x0
local_sigjmp_buf = {{__jmpbuf = {94372882585600,
6959097398727827151, 94372881852832, 94372882803728, 94372882585872, 2,
6959097398784450255,
3801170618011246287}, __mask_was_saved = 0, __saved_mask =
{__val = {140724869506399, 4561020176, 94372856202256, 94372857528766, 64,
140724869506368,
88, 94372881852832, 94372857166446, 94372882585872, 2,
140724869506400, 94372856290490, 2, 94372881852832, 140724869506432}}}}
result = <optimized out>
nprocessed = <optimized out>
saveTopTransactionResourceOwner = 0x55d4e61560c8
saveTopTransactionContext = 0x55d4e61b0fa0
saveActivePortal = 0x0
saveResourceOwner = 0x55d4e61560c8
savePortalContext = 0x0
saveMemoryContext = 0x55d4e61b0fa0
__func__ = "PortalRun"
#9 0x000055d4e48414e5 in exec_simple_query (
query_string=0x55d4e6248930 "select
vquery_c(121.3055419921875,28.596278622860407,129.9647216796875,36.91682310329166,81000,0.01);")
at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/tcop/postgres.c:1075
parsetree = 0x55d4e6249800
portal = 0x55d4e61969a0
snapshot_set = <optimized out>
commandTag = <optimized out>
completionTag = "\000ELECT
1\000\000\000\000\000\000\000\000\260\250\333\017\375\177\000\000\357r\177\344\324U\000\000`\352\000\000\000\000\000\000@
\355\325\344\324U\000\000\320D\025\346\324U\000\000\364y\031\346\324U\000"
querytree_list = <optimized out>
plantree_list = 0x55d4e627ebe0
receiver = 0x55d4e627ec10
format = 0
dest = DestRemote
parsetree_list = 0x55d4e6249930
save_log_statement_stats = 0 '\000'
was_logged = 0 '\000'
msec_str = "\000ELECT
1\000\000\000\000\000\000\000\000\260\250\333\017\375\177\000\000\357r\177\344\324U\000"
parsetree_item = 0x55d4e6249910
isTopLevel = 1 '\001'
#10 PostgresMain (argc=<optimized out>, argv=argv@entry=0x55d4e6155878,
dbname=0x55d4e6155720 "openstreetmap", username=<optimized out>)
at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/tcop/postgres.c:4087
query_string = 0x55d4e6248930 "select
vquery_c(121.3055419921875,28.596278622860407,129.9647216796875,36.91682310329166,81000,0.01);"
firstchar = -434542176
input_message = {data = 0x55d4e6248930 "select
vquery_c(121.3055419921875,28.596278622860407,129.9647216796875,36.91682310329166,81000,0.01);",
len = 102,
maxlen = 1024, cursor = 102}
local_sigjmp_buf = {{__jmpbuf = {140724869506880,
6959097398365019855, 94372881585920, 1, 0, 94372881836048,
6959097398729924303, 3801170603473657551},
__mask_was_saved = 1, __saved_mask = {__val = {0,
140724869507616, 0, 94372881836048, 140612043772104, 8192, 206158430256,
140724869507232,
---Type <return> to continue, or q <return> to quit---
140724869507024, 140724869507072, 94372881586032, 656,
94372881857028, 10, 94372881585920, 94372881586232}}}}
send_ready_for_query = 0 '\000'
__func__ = "PostgresMain"
#11 0x000055d4e46315e9 in BackendRun (port=0x55d4e6192810) at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/postmaster/postmaster.c:4185
ac = 1
secs = 541521482
usecs = 969410
i = 1
av = 0x55d4e6155878
maxac = <optimized out>
#12 BackendStartup (port=0x55d4e6192810) at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/postmaster/postmaster.c:3848
bn = <optimized out>
pid = <optimized out>
#13 ServerLoop () at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/postmaster/postmaster.c:1698
rmask = {fds_bits = {128, 0 <repeats 15 times>}}
selres = <optimized out>
readmask = {fds_bits = {200, 0 <repeats 15 times>}}
now = <optimized out>
last_lockfile_recheck_time = 1488206220
last_touch_time = 1488205152
__func__ = "ServerLoop"
#14 0x000055d4e47fa571 in PostmasterMain (argc=5, argv=<optimized out>)
at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/postmaster/postmaster.c:1322
opt = <optimized out>
status = <optimized out>
userDoption = <optimized out>
listen_addr_saved = 1 '\001'
i = <optimized out>
__func__ = "PostmasterMain"
#15 0x000055d4e463227d in main (argc=5, argv=0x55d4e6154190) at
/build/postgresql-9.3-xceQkK/postgresql-9.3-9.3.16/build/../src/backend/main/main.c:234
Some background information to mention:
I have used some 3rd C libraries in the extension, those libraries use c
standard memory allocation functions such as malloc and calloc other than
the postgres memory management fucntions( palloc and pfree). Those library
implement the data structure of vector, hashtable and priority queue.
