mongoc-ts-pool.c:191 _try_get(): assertion failed: pthread_mutex_lock ((&pool->mtx)) == 0

[df7cb]

@devrimgunduz poked me at pgconf.eu to package mongo_fdw for Debian and I gave it a shot.

The good news is that I got it compiled on trixie-and-newer, the bad news is that it crashes:

create extension mongo_fdw ;
CREATE EXTENSION
create server mongo foreign data wrapper mongo_fdw ;
CREATE SERVER
create user mapping for current_user SERVER mongo ;
CREATE USER MAPPING
CREATE FOREIGN TABLE f_mongo_test (_id name, a int, b varchar) SERVER mongo;
CREATE FOREIGN TABLE
SELECT a, b FROM f_mongo_test ORDER BY 1, 2;
 a │ b 
───┼───
(0 Zeilen)

SELECT a, b FROM f_mongo_test ORDER BY 1, 2;
Server beendete die Verbindung unerwartet
	Das heißt wahrscheinlich, dass der Server abnormal beendete
	bevor oder während die Anweisung bearbeitet wurde.

Mongo log for the last two commands:

{"t":{"$date":"2025-10-28T13:14:43.406+00:00"},"s":"I",  "c":"NETWORK",  "id":22943,   "ctx":"listener","msg":"Connection accepted","attr":{"remote":"172.17.0.1:41340","isLoadBalanced":false,"uuid":{"uuid":{"$uuid":"7ff1739b-0464-4d73-a850-d14424c4fb65"}},"connectionId":4,"connectionCount":1}}
{"t":{"$date":"2025-10-28T13:14:43.406+00:00"},"s":"I",  "c":"NETWORK",  "id":51800,   "ctx":"conn4","msg":"client metadata","attr":{"remote":"172.17.0.1:41340","client":"conn4","negotiatedCompressors":[],"doc":{"driver":{"name":"mongoc","version":"2.1.2"},"platform":"cfg=0x07235e88e9 posix=200809 stdc=199901 CC=GCC 15.2.0 CFLAGS=\"-g -O2 -Werror=implicit-function-declaration -ffile-prefix-map=/build/reproducible-path/mongo-c-driver-2.1.2=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -Wdate-time -D_FORTIFY_SOURCE=2\" LDFLAGS=\"-Wl,-z,relro -Wl,-z,now -lpthread\"","os":{"type":"Linux"}}}}
{"t":{"$date":"2025-10-28T13:14:43.406+00:00"},"s":"I",  "c":"ACCESS",   "id":10483900,"ctx":"conn4","msg":"Connection not authenticating","attr":{"client":"172.17.0.1:41340","doc":{"driver":{"name":"mongoc","version":"2.1.2"},"platform":"cfg=0x07235e88e9 posix=200809 stdc=199901 CC=GCC 15.2.0 CFLAGS=\"-g -O2 -Werror=implicit-function-declaration -ffile-prefix-map=/build/reproducible-path/mongo-c-driver-2.1.2=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -Wdate-time -D_FORTIFY_SOURCE=2\" LDFLAGS=\"-Wl,-z,relro -Wl,-z,now -lpthread\"","os":{"type":"Linux"}}}}
{"t":{"$date":"2025-10-28T13:14:43.407+00:00"},"s":"I",  "c":"NETWORK",  "id":6788700, "ctx":"conn4","msg":"Received first command on ingress connection since session start or auth handshake","attr":{"elapsedMillis":0}}

{"t":{"$date":"2025-10-28T13:14:47.229+00:00"},"s":"I",  "c":"NETWORK",  "id":22944,   "ctx":"conn4","msg":"Connection ended","attr":{"remote":"172.17.0.1:41340","isLoadBalanced":false,"uuid":{"uuid":{"$uuid":"7ff1739b-0464-4d73-a850-d14424c4fb65"}},"connectionId":4,"connectionCount":0}}

PG log:

./src/libmongoc/src/mongoc/mongoc-ts-pool.c:191 _try_get(): assertion failed: pthread_mutex_lock ((&pool->mtx)) == 0
2025-10-28 13:14:47.229 UTC [1291486] LOG:  client backend (PID 1297825) was terminated by signal 6: Aborted
2025-10-28 13:14:47.229 UTC [1291486] DETAIL:  Failed process was running: SELECT a, b FROM f_mongo_test ORDER BY 1, 2;

This is mongo_fdw 5.5.3 on PG 18.0 (cassert enabled) on Debian sid with libmongoc-dev 2.1.2-1.

[df7cb]

No crash with libmongoc-dev 1.30.4-1 (Debian trixie), btw.