Question

I do not understand why application goes down when there are too many requests? How can I test my application for its maximum capacity to respond to a requests?

Answer 1

我不理解为什么在要求太多的时候,申请会减少?

如果你要求具体应用,答案就是我们不知道什么,我们没有任何证据可以推断问题是什么。寻找证据的地点:

Check server the logs.
If you have a reverse proxy, check the proxy s logs.
Check the backend database logs.
Check the system-level performance stats; e.g. look for evidence of VM thrashing, disc I/O overload and so on.
Check for pathological GC behavior.
Check for blocked / jammed threads, indicating concurrency bottlenecks, deadlocks and so on.

If you are asking in the general case, there can be any number of causes:

Running out of an external resource (e.g. database connections)
Creating too many threads
Trying to queue every request to avoid dropping requests, and other broken strategies.
Concurrency bottlenecks
Pathological algorithm or database query design that results in performance that decays under load.
Broken error recovery; e.g. underload you start getting unexpected exceptions, and this triggers resource leaks.
And so on ...

以及我如何测试我的申请,使其具有最大能力回应请求......

Create a test harness to repeatedly send requests to your server and see what rate the server can sustain. There are existing freameworks for doing this.

Answer 2

为什么你认为申请被放弃? 难道它只是采取一些长期行动吗?

“太多要求”的音响,例如,你要么没有资源(例如与非行的联系),但你应当看到一些例外情况在案件记录中有所追溯,或者你有某种一致性的问题。

To know for sure, you need to make thread dump and see if all threads are doing what you expect them to do. You can pay attention to threads of your application only at the start (database threads, logic and servlet threads), as it somewhat unlikely that Tomcat or SQL server has some bug inside them. Try to find place where your application stop behaving as you expect it to, by looking into logs (or adding them, if needed).

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