[英]fastapi + aiomysql connection pool stuck after 10 calls
為什么aiomysql連接池在N次調用后卡住了? (N是maxsize
連接數。嘗試了默認的N=10和N=3)
我認為獲得的連接會在退出時自動關閉async with
。
這是重現的最小腳本:
from fastapi import FastAPI
import aiomysql
import secret
app = FastAPI()
@app.on_event("startup")
async def _startup():
app.state.pool = await aiomysql.create_pool(host=secret.DB_URL, port=3306, user=secret.DB_USERNAME, password=secret.DB_PASSWORD, db=secret.DB_DATABASE)
print("startup done")
async def _get_query_with_pool(pool):
async with await pool.acquire() as conn:
async with conn.cursor(aiomysql.DictCursor) as cur:
await cur.execute("SELECT 1")
return await cur.fetchall()
@app.get("/v1/get_data")
async def _get_data():
return await _get_query_with_pool(app.state.pool)
if __name__ == "__main__":
import uvicorn
uvicorn.run(app, host="0.0.0.0", port=8000)
原來罪魁禍首是 pool.acquire() 之前的額外等待
async def _get_query_with_pool(pool):
async with await pool.acquire() as conn:
async with conn.cursor(aiomysql.DictCursor) as cur:
await cur.execute("SELECT 1")
return await cur.fetchall()
刪除 pool.acquire() 之前的額外等待,因此:
async def _get_query_with_pool(pool):
async with pool.acquire() as conn:
async with conn.cursor(aiomysql.DictCursor) as cur:
await cur.execute("SELECT 1")
return await cur.fetchall()
現在連接成功
2021 年第四季度更新:
原來連接池是不值得的。 連接池會導致 mysql8 alter table 永遠鎖定。 只需打開和關閉數據庫連接。
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