在greenlets中捕获引发的异常

Question

我试图捕获在绿色线程中引发的异常。根据这篇教程，不幸的是，“在Greenlet中引发的异常仍然保留在Greenlet内部”。在下面的代码中，我有一个同步方法，它生成爬行Greenlet。这些爬行Greenlet引发HTTPError异常，我需要在同步方法的主体中捕获它们。根据异常，在同步方法中我将设置Account对象的适当状态。有什么办法可以在sync方法中捕获在greenlets中引发的异常，以实现这一目标？谢谢！

# this is standalone helper method
def crawl(item):
    try:
        item.refresh_children(False) # THROWS HTTPError exception
        greenlets = [gevent.spawn_link_exception(crawl, child) for child in item.children]
        gevent.joinall(greenlets)
    except HTTPError, e:
        print e.message
        raise e
    except (JSONDecodeError, InvalidCredentialsException) as e:
        print e.message
        raise e

# this is instance method of the Account class 
def sync(self):
    "Sync search index with data from source"
    try:
        greenlets = [gevent.spawn_link_exception(crawl, item) for item in self.get_navigation()]
        gevent.joinall(greenlets)
        self.date_synced = datetime.datetime.now()
        self.save()
    except HTTPError, e:
        if e.status_code == 401:
            self.status = 'revoked'
        else:
            self.status = 'error'
        self.save()
    except LinkedFailed, e:
        print e.message
        exception_name = e.message.split()[-1]
        if exception_name in ['HTTPError', 'JSONDecodeError']:
            self.status = 'error'
            self.save()
        elif exception_name == 'InvalidCredentialsException':
            self.status = 'revoked'
            self.save()

- Arman

Answer 1

Greenlets将保存为greenlet生成的函数的结果或者异常（如果有）。您可以使用get方法获取结果或重新引发异常。由于您似乎是基于任何一个Greenlet出错来更改状态，因此同步方法最终会看起来像：

def sync(self):
    "Sync search index with data from source"
    greenlets = [gevent.spawn_link_exception(crawl, item) for item in self.get_navigation()]
    gevent.joinall(greenlets)
    try:
        results = [greenlet.get() for greenlet in greenlets]
    except HTTPError, e:
        if e.status_code == 401:
            self.status = 'revoked'
        else:
            self.status = 'error'
        self.save()
    except LinkedFailed, e:
        print e.message
        exception_name = e.message.split()[-1]
        if exception_name in ['HTTPError', 'JSONDecodeError']:
            self.status = 'error'
            self.save()
        elif exception_name == 'InvalidCredentialsException':
            self.status = 'revoked'
            self.save()

    self.date_synced = datetime.datetime.now()
    self.save()

- Philip Cristiano