Django 事务错误

Question

我有一个 cronjob 来处理电子邮件并将它们存储在系统中。它已经运行了一年多，但现在突然间它开始时不时地随机给出这些奇怪的交易错误。

2010-09-02-01:45:11 ERROR Exception occured during mail processing
Traceback (most recent call last):
 File "/var/www/example.com/project/scripts/cronjobs.py", line 453, in process_msg
   source, email, 'i' if rejection_reason else 'v', rejection_reason)
 File "/usr/lib/python2.5/site-packages/django/db/transaction.py", line 267, in _commit_manually
   leave_transaction_management()
 File "/usr/lib/python2.5/site-packages/django/db/transaction.py", line 77, in leave_transaction_management
   raise TransactionManagementError("Transaction managed block ended with pending COMMIT/ROLLBACK")
TransactionManagementError: Transaction managed block ended with pending COMMIT/ROLLBACK

它没有任何理由发生，我没有任何其他上下文信息可用。这是我的 process_msg 函数的结构：

@commit_manually
def save_email( u,l, d, t, s, e, status, reason):
    try:
        # ... bla bla bla ... 
        commit()
    exception, e:
        rollback()
        raise e

def process_msg(m):
    try:
        #....
        save_email(u, l, d, t
            source, email, 'i' if rejection_reason else 'v', rejection_reason)
        #....
     except Exception, e:
        logger.error('Error while processing email', exc_info=True )
        return None
    else:
        return True

我如何调查这个问题？

Answer 1

似乎在输入save_email() 之前发生了错误。如果 process_msg() 中没有 commit() 或 rollback() 指令，则会引发 TransactionError。

您可以尝试用调试器圈出错误：

def process_msg(m):
    try:
        import pdb                    # import python debugger
        pdb.set_trace()               # begin debugging
        #....
        save_email(u, l, d, t,
        […]

您可以在Python website 上找到有关如何使用调试器的信息。