MagicStack / MagicStack/asyncpg
Handle additional InterfaceError types when inside a transaction
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Descrizione
* **asyncpg version**: `0.26.0`
* **PostgreSQL version**: `PostgreSQL 14.5 (Debian 14.5-1.pgdg110+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 10.2.1-6) 10.2.1 20210110, 64-bit` - Also fails on older versions such as PG 13
* **Do you use a PostgreSQL SaaS? If so, which? Can you reproduce
the issue with a local PostgreSQL install?**: Google CloudSQL, but I'm reproducing this locally in a test.
* **Python version**: 3.10
* **Platform**: MacOS
* **Do you use pgbouncer?**: No
* **Did you install asyncpg with pip?**: yes
* **If you built asyncpg locally, which version of Cython did you use?**: n/a
* **Can the issue be reproduced under both asyncio and
[uvloop](https://github.com/magicstack/uvloop)?**: yes
When an InterfaceError is raised during a transaction, `asyncpg` does not explicitly handle all variants of this exception, and raises it.
https://github.com/MagicStack/asyncpg/blob/5f908e679a6264c5fcf8a92895a2f34a9387e4da/asyncpg/transaction.py#L65-L79
For example, it does not handle the type `asyncpg.exceptions.ConnectionDoesNotExistError` - and as such, this leads to leftover connections while trying to close the pool. Simple reproduction that forces the error by setting `idle_in_transaction_session_timeout` to be very small - basically telling the server to close a connection before it can complete a query:
```python
pool = await asyncpg.create_pool(
dsn=dsn,
min_size=1,
max_size=4,
server_settings={
"idle_in_transaction_session_timeout": "1",
},
)
async def query_gen():
async with pool.acquire(timeout=5) as con:
async with con.transaction(readonly=True):
await con.fetch(
"SELECT * FROM my_db.my_schema.my_table;", timeout=15
)
tasks = []
for i in range(40):
tasks.append(query_gen())
results = await asyncio.gather(*tasks, return_exceptions=True)
print(results, flush=True)
await pool.close()
```
The `results` List is all exceptions:
```
[InterfaceError('cannot call Transaction.__aexit__(): the underlying connection is closed'), InterfaceError('cannot call Transaction.__aexit__(): the underlying connection is closed'), InterfaceError('cannot call Transaction.__aexit__(): the underlying connection is closed'), InterfaceError('cannot call Transaction.__aexit__(): the underlying connection is closed'), ...]
```
The exception type is `asyncpg.exceptions.ConnectionDoesNotExistError`. And the `pool.close()` will print a warning:
```
asyncpg.pool:Pool.close() is taking over 60 seconds to complete. Check if you have any unreleased connections left. Use asyncio.wait_for() to set a timeout for Pool.close().
```
When this happens, I do believe the connection pool should set the `_in_use` attribute for the connection holder to `False` and / or delete the pool connection holder.
This does not happen when not using the `async with con.transaction()` context manager.
Note: Under normal conditions / default settings, I see this rarely, however, I do see the `pool.close()` warning on occasion.
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Direzione di ricerca
Inizia in asyncpg/transaction.py alle righe collegate 65-79, quindi esegui la riproduzione asyncio fornita con idle_in_transaction_session_timeout impostato su 1. Traccia l’effetto di ConnectionDoesNotExistError durante la transazione sul pool e verifica che la connessione venga rilasciata e che pool.close() venga completato senza l’avviso relativo alla connessione non rilasciata.
Scritto dal modello di indicizzazione a partire dal testo della issue.
Valutazione
- Stack tecnologico
- postgresql, python
- Ambito
- database
- Tipo di issue
- Bug
- Difficoltà
- 3/5
- Tempo stimato
- 1-2 giorni
- Stato di attività
- Ferma
- Chiarezza
- Abbastanza chiara
- Idoneità per principianti
- 38/100