psycopg2错误：DatabaseError：错误，没有来自libpq的消息 [英] psycopg2 error: DatabaseError: error with no message from the libpq

问题描述

我有一个应用程序，可以将csv文件中的数据解析并将其加载到Postgres 9.3数据库中。在串行执行中，插入语句/游标执行没有问题。

I have an application that parses and loads data from csv files into a Postgres 9.3 database. In serial execution insert statements/cursor executions work without an issue.

我在混合中添加了celery，以添加并行解析和数据文件的插入。解析工作正常。但是，我去运行插入语句，然后得到：

I added celery in the mix to add parallel parsing and inserting of the data files. Parsing works fine. However, I go to run insert statements and I get:

[2015-05-13 11:30:16,464:  ERROR/Worker-1] ingest_task.work_it: Exception
    Traceback (most recent call last):
    File "ingest_tasks.py", line 86, in work_it
        rowcount = ingest_data.load_data(con=con, statements=statements)
    File "ingest_data.py", line 134, in load_data
        ingest_curs.execute(statement)
    DatabaseError: error with no message from the libpq

推荐答案

在多处理 engine.execute（ ）。我终于解决了这个问题，就像在 engine.dispose（） http://docs.sqlalchemy.org/en/rel_0_9/core/connections.html#engine-disposal rel = noreferrer>官方文件：

I encountered a similar problem when multiprocessing engine.execute(). I solved this problem finally by just adding engine.dispose() right in the first line under the function where the subprocess is supposed to enter, as suggested in the official document:

当程序使用多处理或 fork（）和 Engine 对象时如果
复制到子进程中，则应调用 Engine.dispose（），以便
引擎在该派生本地创建全新的数据库连接。数据库
连接通常不跨进程边界传播。

When a program uses multiprocessing or fork(), and an Engine object is copied to the child process, Engine.dispose() should be called so that the engine creates brand new database connections local to that fork. Database connections generally do not travel across process boundaries.

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