CODEWITHSUNDEEP
asp.net
user70192
user70192

Reputation: 14204

How could you detect programmatically when your server is over capacity in ASP.NET?

One of the interesting things about Twitter is the over capacity, fail whale. My question is, programmatically, how can they detect when their system is over capacity? Is there a special type of exception that gets thrown in this case?

Upvotes: 0

Views: 250

Answers (4)

quillbreaker
quillbreaker

Reputation: 6225

Diskeeper tells you that your system is stressed if you've used over a certain portion of your virtual memory, which I thought was interesting at the time.

Upvotes: 0

Steven Sudit
Steven Sudit

Reputation: 19620

Presumably, they've done basic load-testing so they have a solid idea of how much they can process before slowing down unacceptably or even crashing.

Upvotes: 0

ceejayoz
ceejayoz

Reputation: 180004

There are any number of things that could be used to determine this - it'll depend on the system and what metrics the devs decide to use. A few examples:

  • vBulletin, a PHP-based forum system can shut itself down if the Unix load average hits a certain (admin-selected) value
  • Some systems that involve queuing (as Twitter does) can monitor the size of the queue and shut out users if the queue grows too large
  • Some systems have the servers doing the actual processing behind a proxy or load balancer. If they go offline, the proxy or load balancer can redirect traffic to an error page like the failwhale.

Upvotes: 2

Daniel A. White
Daniel A. White

Reputation: 190945

I believe its the routers/load balancer's detect this for twitter. If a machine or group of machines have large number of exceptions or return some HTTP 5xx errors, then the load balancers fail over to a "fail whale" server.

Upvotes: 0

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