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[Bug]: DELETE /{db} returns 500 badarg instead of 404 when the shard map cache still lists a just-deleted database

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Evaluación

Dificultad
1/5
Tiempo estimado
Menos de una hora
Aptitud para principiantes
90/100
Tipo de issue
Error
Claridad
Bien especificado
Estado de actividad
Activo
Stack tecnológico
erlang
Área
api, backend, databases

Línea de trabajo

Comienza en src/fabric/src/fabric_db_delete.erl, en fabric_db_delete:maybe_stop/2, concretamente en la rama en la que cada shard devuelve not_found. Comprueba el formato de la advertencia y verifica el comportamiento completado con la reproducción de concurrent-reader informada: el segundo DELETE devuelve 404 con not_found y la advertencia se registra en lugar de producir un 500 badarg.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

Version

3.5.1

Describe the problem you're encountering

Right after a database is deleted, a second DELETE /{db} can answer 500 {"error":"unknown_error","reason":"badarg"} instead of 404 not_found. The stack trace in the log points to fabric_db_delete:maybe_stop/2.

That branch should turn "every shard answered not_found" into {stop, not_found}, but it crashes while formatting its own log message:

%% src/fabric/src/fabric_db_delete.erl (line 79 in 3.5.1, line 78 in 3.5.2 and main)
{W, 0, W} ->
    {#shard{dbname = Name}, _} = hd(Counters),
    couch_log:warning("~p not_found ~d", [?MODULE, Name]),
    {stop, not_found};

Name is a binary, so ~d raises badarg and the request fails with a 500.

This branch is only reached when the shard map cache (mem3) still lists the database after it was deleted, for example when a read that raced with the deletion put its shards back in the cache. Until the cache catches up, other requests on that database also fail with 500 "No DB shards could be opened.". That part may be expected while the deletion propagates; the badarg is not.

Expected Behaviour

The second DELETE should answer 404 {"error":"not_found","reason":"Database does not exist."}, and the warning should be logged. Using ~s (or ~p) instead of ~d in that format string should be enough.

Steps to Reproduce

On a single-node CouchDB 3.5.1 (couchdb:3.5.1 Docker image, default config). Replace $COUCH with the server URL including admin credentials.

DB=badarg_repro
curl -s -X PUT "$COUCH/$DB"
# a few concurrent readers
for i in 1 2 3 4; do
  ( while true; do curl -s -o /dev/null "$COUCH/$DB"; done ) &
done
curl -s -X DELETE "$COUCH/$DB"   # {"ok":true}
curl -s -X DELETE "$COUCH/$DB"   # often: 500 {"error":"unknown_error","reason":"badarg","ref":...}
kill %1 %2 %3 %4

With this script, the second DELETE answered 500 badarg (always "ref":17476293) in 14 of 40 runs on our machine; a tighter loop hit it in 188 of 200. With no concurrent readers it did not reproduce (0 out of 150).

Your Environment
  • CouchDB 3.5.1, official Docker image, single node
  • Seen from the CouchDB integration tests of rouchdb, on a GitHub Actions Linux runner and on Docker Desktop for macOS
Additional Context

The format string is the same in 3.5.2 and on main, so those are likely affected as well. On the client side we now retry these 500s for about a second after a delete.

Lenguaje dominante
Erlang
Estrellas
7k
Forks
1.1k
Merge medio
2 d 10 h
PR fusionados (30 d)
18

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