我的后端是用Python编写的,使用CherryPy。我的代码中有一部分处理前端的长轮询,如下所示:
# for the long-polls
longpoll_blockers_channel = {}
class MyApp:
...
@cherrypy.expose
@uses_json
def register_longpoll_blocker(self, classmodel_name):
if classmodel_name not in longpoll_blockers_channel:
unblock_event_obj = threading.Event()
unblock_event_obj.running_status = "long-polling"
longpoll_blockers_channel[classmodel_name] = unblock_event_obj
def unblocking_event_handler(mapper, connection, target):
longpoll_blockers_channel[classmodel_name].set()
listento_classmodel_obj = database.schemas_registry[classmodel_name]
# triggered by trio events:
for data_changing_evt in [
'after_delete', 'after_insert', 'after_update'
]:
sqlalchemy.event.listen(listento_classmodel_obj, data_changing_evt,
unblocking_event_handler)
return f"Successfully registered a blocker at backend for {classmodel_name}!"
我注意到上面的代码似乎只能处理多达4个长轮询注册线程。达到4或更多后,后端将冻结。我怀疑冻结是由threading.Event()
产生的线程太多造成的,但无法证明这一点。我想找出到底是什么导致后端挂起
有许多threading.Event()
线程可能会冻结应用程序吗?如何调试这样的bug
经过几天的研究,我发现这种空闲是由于浏览器的
blocking
机制造成的,它只允许同时进行一定数量的并行连接。它与Python的后端和线程无关相关问题 更多 >
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