相关疑难解决方法(0)

根据http://docs.sqlalchemy.org/en/rel_0_9/core/pooling.html#disconnect-handling-pessimistic,如果连接池中的条目不再有效,可以检测SQLAlchemy重新连接.我创建了以下测试用例来测试它:

import subprocess
from sqlalchemy import create_engine, event
from sqlalchemy import exc
from sqlalchemy.pool import Pool

@event.listens_for(Pool, "checkout")
def ping_connection(dbapi_connection, connection_record, connection_proxy):
    cursor = dbapi_connection.cursor()
    try:
        print "pinging server"
        cursor.execute("SELECT 1")
    except:
        print "raising disconnect error"
        raise exc.DisconnectionError()
    cursor.close()

engine = create_engine('postgresql://postgres@localhost/test')

connection = engine.connect()

subprocess.check_call(['psql', str(engine.url), '-c',
    "select pg_terminate_backend(pid) from pg_stat_activity " +
    "where pid <> pg_backend_pid() " +
    "and datname='%s';" % engine.url.database],
    stdout=subprocess.PIPE)

result = connection.execute("select 'OK'")
for row in result:
    print "Success!", " ".join(row)

但是没有恢复,我收到了这个例外: …