configuration-templates – Diff between revs 48 and 60
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| 1 | vcl 4.0; |
1 | vcl 5.0; |
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| 2 | ########################################################################### |
2 | ########################################################################### |
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| 3 | ## Copyright (C) Wizardry and Steamworks 2016 - License: GNU GPLv3 ## |
3 | ## Copyright (C) Wizardry and Steamworks 2016 - License: GNU GPLv3 ## |
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| 4 | ## Please see: http://www.gnu.org/licenses/gpl.html for legal details, ## |
4 | ## Please see: http://www.gnu.org/licenses/gpl.html for legal details, ## |
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| 5 | ## rights of fair usage, the disclaimer and warranty conditions. ## |
5 | ## rights of fair usage, the disclaimer and warranty conditions. ## |
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| 6 | ########################################################################### |
6 | ########################################################################### |
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| Line 300... | Line 300... | |||
| 300 | # When several clients are requesting the same page Varnish will send one request to the backend and place the others on hold while fetching one copy from the backend. In some products this is called request coalescing and Varnish does this automatically. |
300 | # When several clients are requesting the same page Varnish will send one request to the backend and place the others on hold while fetching one copy from the backend. In some products this is called request coalescing and Varnish does this automatically. |
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| 301 | # If you are serving thousands of hits per second the queue of waiting requests can get huge. There are two potential problems - one is a thundering herd problem - suddenly releasing a thousand threads to serve content might send the load sky high. Secondly - nobody likes to wait. To deal with this we can instruct Varnish to keep the objects in cache beyond their TTL and to serve the waiting requests somewhat stale content. |
301 | # If you are serving thousands of hits per second the queue of waiting requests can get huge. There are two potential problems - one is a thundering herd problem - suddenly releasing a thousand threads to serve content might send the load sky high. Secondly - nobody likes to wait. To deal with this we can instruct Varnish to keep the objects in cache beyond their TTL and to serve the waiting requests somewhat stale content. |
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| 302 | # if (!std.healthy(req.backend_hint) && (obj.ttl + obj.grace > 0s)) { |
302 | # if (!std.healthy(req.backend_hint) && (obj.ttl + obj.grace > 0s)) { |
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| 303 | # return (deliver); |
303 | # return (deliver); |
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| 304 | # } else { |
304 | # } else { |
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| 305 | # return (fetch); |
305 | # return (miss); |
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| 306 | # } |
306 | # } |
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| Line 307... | Line 307... | |||
| 307 | |
307 | |
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| 308 | # We have no fresh fish. Lets look at the stale ones. |
308 | # We have no fresh fish. Lets look at the stale ones. |
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| 309 | if (std.healthy(req.backend_hint)) { |
309 | if (std.healthy(req.backend_hint)) { |
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| 310 | # Backend is healthy. Limit age to 10s. |
310 | # Backend is healthy. Limit age to 10s. |
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| 311 | if (obj.ttl + 10s > 0s) { |
311 | if (obj.ttl + 10s > 0s) { |
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| 312 | #set req.http.grace = "normal(limited)"; |
312 | #set req.http.grace = "normal(limited)"; |
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| 313 | return (deliver); |
313 | return (deliver); |
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| 314 | } else { |
314 | } else { |
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| 315 | # No candidate for grace. Fetch a fresh object. |
315 | # No candidate for grace. Fetch a fresh object. |
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| 316 | return(fetch); |
316 | return (miss); |
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| 317 | } |
317 | } |
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| 318 | } else { |
318 | } else { |
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| 319 | # backend is sick - use full grace |
319 | # backend is sick - use full grace |
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| 320 | if (obj.ttl + obj.grace > 0s) { |
320 | if (obj.ttl + obj.grace > 0s) { |
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| 321 | #set req.http.grace = "full"; |
321 | #set req.http.grace = "full"; |
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| 322 | return (deliver); |
322 | return (deliver); |
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| 323 | } else { |
323 | } else { |
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| 324 | # no graced object. |
324 | # no graced object. |
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| 325 | return (fetch); |
325 | return (miss); |
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| 326 | } |
326 | } |
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| Line 327... | Line 327... | |||
| 327 | } |
327 | } |
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| 328 | |
328 | |
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| 329 | # fetch & deliver once we get the result |
329 | # fetch & deliver once we get the result |
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| Line 330... | Line 330... | |||
| 330 | return (fetch); # Dead code, keep as a safeguard |
330 | return (miss); # Dead code, keep as a safeguard |
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| 331 | } |
331 | } |
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| 332 | |
332 | |
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