pymongo中的Tailable游标似乎已停止工作

Question

我已经成功地在Pymongo使用了2年的tailable游标，但突然间，今天，我的相同代码抛出了“意外的关键字”错误：

我几周前升级到3.0 Mongo并且它仍然运行良好，但是现在可能是一个新的pymongo版本，因为我今天刚刚安装了新版本（3.0.1）？以前是pymongo 2.6.3。我的代码：

cursor = refreq.find(tailable = True, await_data = True)
while cursor.alive:
    xxx

所以基本上任何时候插入refreq集合的东西我想知道它，没有轮询。习惯工作正常。最近安装了Pymongo 3.0.1版（今天）。

试图投入一个空的字典

cursor = refreq.find({}, tailable = True, await_data = True)

但仍然给出相同的错误。有什么变化吗？

这是完整的线程代码，供参考：

def handleRefRequests(db, refqueue):
    """ handles reference data requests. It's threaded. Needs the database id. 
    will create a capped collection and constantly poll it for new requests"""
    print("Dropping the reference requests collection")
    db.drop_collection("bbrefrequests")
    print("Recreating the reference requests collection")
    db.create_collection("bbrefrequests", capped = True, size = 100 * 1000000) # x * megabytes
    refreq = db.bbrefrequests
    # insert a dummy record otherwise exits immediately
    refreq.insert({"tickers":"test", "fields":"test", "overfields":"test", "overvalues":"test", "done": False})
    cursor = refreq.find({}, tailable = True, await_data = True)
    while cursor.alive:
        try:
            post = cursor.next()
            if ("tickers" in post) and ("fields" in post) and ("done" in post): # making sure request is well formed
                if post["tickers"] != "test":
                    refqueue.put(post)
        except StopIteration:
            time.sleep(0.1)
        if not runThreads:
            print("Exiting handleRefRequests thread")
            break