Why aren't the 2nd and 3rd requests for the same image cached?
Question
The original website isn't caching html, css, or images the way I think it should. The results from google chrome har for just a single image while requesting different pages on the website are below. It is part of a larger browsing of a website trying to figure out why the browser thinks it should be cached but the browser is re-requested from server. I removed all har not specificially related to this image.
I don't have any cache-killer or cache-disabler on. I even went to relatively clean computer to make sure there weren't any dev tools installed that might mess with the cache.
All the request/response headers from the first request appear to imply that the 2nd and 3rd requests should not make re-requests but come from browser local cache.
What am I missing?
{
"startedDateTime": "2017-02-10T21:21:44.273Z",
"time": 56.46199999999624,
"request": {
"method": "GET",
"url": "http://616206ee2c1b2155fd11-21abbde6fa52e03b7fd037b3488bb991.r53.cf1.rackcdn.com/images/default-source/site-cdn/LoginLogo.png",
"httpVersion": "HTTP/1.1",
"headers": [
{
"name": "Accept",
"value": "image/webp,image/*,*/*;q=0.8"
},
{
"name": "Connection",
"value": "keep-alive"
},
{
"name": "Accept-Encoding",
"value": "gzip, deflate, sdch"
},
{
"name": "Referer",
"value": "http://authentrip.com/"
},
{
"name": "Host",
"value": "616206ee2c1b2155fd11-21abbde6fa52e03b7fd037b3488bb991.r53.cf1.rackcdn.com"
},
{
"name": "Accept-Language",
"value": "en-US,en;q=0.8"
},
{
"name": "User-Agent",
"value": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.116 Safari/537.36"
}
],
"queryString": [],
"cookies": [],
"headersSize": 428,
"bodySize": 0
},
"response": {
"status": 200,
"statusText": "OK",
"httpVersion": "HTTP/1.1",
"headers": [
{
"name": "Date",
"value": "Fri, 10 Feb 2017 21:21:44 GMT"
},
{
"name": "Origin",
"value": "https://mycloud.rackspace.com"
},
{
"name": "Last-Modified",
"value": "Fri, 09 Dec 2016 05:10:48 GMT"
},
{
"name": "ETag",
"value": "ab904584a8e355da2fd0437065839e10"
},
{
"name": "Content-Type",
"value": "image/png"
},
{
"name": "X-Timestamp",
"value": "1481260247.52133"
},
{
"name": "Cache-Control",
"value": "public, max-age=349"
},
{
"name": "Content-Length",
"value": "6397"
},
{
"name": "Connection",
"value": "keep-alive"
},
{
"name": "Accept-Ranges",
"value": "bytes"
},
{
"name": "X-Trans-Id",
"value": "txbeec00752b6a4e1e9e3b5-00589e2ca4dfw1"
},
{
"name": "Expires",
"value": "Fri, 10 Feb 2017 21:27:33 GMT"
}
],
"cookies": [],
"content": {
"size": 6397,
"mimeType": "image/png",
"compression": 0
},
"redirectURL": "",
"headersSize": 433,
"bodySize": 6397,
"_transferSize": 6830
},
"cache": {},
"timings": {
"blocked": 0.396999999992431,
"dns": -1,
"connect": -1,
"send": 0.13800000000685503,
"wait": 23.861999999994016,
"receive": 32.06500000000294,
"ssl": -1
},
"serverIPAddress": "204.2.145.184",
"connection": "989",
"pageref": "page_1"
},
{
"startedDateTime": "2017-02-10T21:22:48.357Z",
"time": 0,
"request": {
"method": "GET",
"url": "http://616206ee2c1b2155fd11-21abbde6fa52e03b7fd037b3488bb991.r53.cf1.rackcdn.com/images/default-source/site-cdn/LoginLogo.png",
"httpVersion": "HTTP/1.1",
"headers": [
{
"name": "Accept",
"value": "image/webp,image/*,*/*;q=0.8"
},
{
"name": "Connection",
"value": "keep-alive"
},
{
"name": "Accept-Encoding",
"value": "gzip, deflate, sdch"
},
{
"name": "Referer",
"value": "http://authentrip.com/"
},
{
"name": "Host",
"value": "616206ee2c1b2155fd11-21abbde6fa52e03b7fd037b3488bb991.r53.cf1.rackcdn.com"
},
{
"name": "Accept-Language",
"value": "en-US,en;q=0.8"
},
{
"name": "User-Agent",
"value": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.116 Safari/537.36"
}
],
"queryString": [],
"cookies": [],
"headersSize": 428,
"bodySize": 0
},
"response": {
"status": 200,
"statusText": "OK",
"httpVersion": "HTTP/1.1",
"headers": [
{
"name": "Date",
"value": "Fri, 10 Feb 2017 21:21:44 GMT"
},
{
"name": "Origin",
"value": "https://mycloud.rackspace.com"
},
{
"name": "Last-Modified",
"value": "Fri, 09 Dec 2016 05:10:48 GMT"
},
{
"name": "ETag",
"value": "ab904584a8e355da2fd0437065839e10"
},
{
"name": "Content-Type",
"value": "image/png"
},
{
"name": "X-Timestamp",
"value": "1481260247.52133"
},
{
"name": "Cache-Control",
"value": "public, max-age=349"
},
{
"name": "Content-Length",
"value": "6397"
},
{
"name": "Connection",
"value": "keep-alive"
},
{
"name": "Accept-Ranges",
"value": "bytes"
},
{
"name": "X-Trans-Id",
"value": "txbeec00752b6a4e1e9e3b5-00589e2ca4dfw1"
},
{
"name": "Expires",
"value": "Fri, 10 Feb 2017 21:27:33 GMT"
}
],
"cookies": [],
"content": {
"size": 6397,
"mimeType": "image/png"
},
"redirectURL": "",
"headersSize": 433,
"bodySize": 0,
"_transferSize": 0
},
"cache": {},
"timings": {
"blocked": -1,
"dns": -1,
"connect": -1,
"send": 0,
"wait": 0,
"receive": 0,
"ssl": -1
},
"serverIPAddress": "204.2.145.184",
"connection": "989",
"pageref": "page_2"
}
{
"startedDateTime": "2017-02-10T21:23:38.412Z",
"time": 0,
"request": {
"method": "GET",
"url": "http://616206ee2c1b2155fd11-21abbde6fa52e03b7fd037b3488bb991.r53.cf1.rackcdn.com/images/default-source/site-cdn/LoginLogo.png",
"httpVersion": "HTTP/1.1",
"headers": [
{
"name": "Accept",
"value": "image/webp,image/*,*/*;q=0.8"
},
{
"name": "Connection",
"value": "keep-alive"
},
{
"name": "Accept-Encoding",
"value": "gzip, deflate, sdch"
},
{
"name": "Referer",
"value": "http://authentrip.com/"
},
{
"name": "Host",
"value": "616206ee2c1b2155fd11-21abbde6fa52e03b7fd037b3488bb991.r53.cf1.rackcdn.com"
},
{
"name": "Accept-Language",
"value": "en-US,en;q=0.8"
},
{
"name": "User-Agent",
"value": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.116 Safari/537.36"
}
],
"queryString": [],
"cookies": [],
"headersSize": 428,
"bodySize": 0
},
"response": {
"status": 200,
"statusText": "OK",
"httpVersion": "HTTP/1.1",
"headers": [
{
"name": "Date",
"value": "Fri, 10 Feb 2017 21:21:44 GMT"
},
{
"name": "Origin",
"value": "https://mycloud.rackspace.com"
},
{
"name": "Last-Modified",
"value": "Fri, 09 Dec 2016 05:10:48 GMT"
},
{
"name": "ETag",
"value": "ab904584a8e355da2fd0437065839e10"
},
{
"name": "Content-Type",
"value": "image/png"
},
{
"name": "X-Timestamp",
"value": "1481260247.52133"
},
{
"name": "Cache-Control",
"value": "public, max-age=349"
},
{
"name": "Content-Length",
"value": "6397"
},
{
"name": "Connection",
"value": "keep-alive"
},
{
"name": "Accept-Ranges",
"value": "bytes"
},
{
"name": "X-Trans-Id",
"value": "txbeec00752b6a4e1e9e3b5-00589e2ca4dfw1"
},
{
"name": "Expires",
"value": "Fri, 10 Feb 2017 21:27:33 GMT"
}
],
"cookies": [],
"content": {
"size": 6397,
"mimeType": "image/png"
},
"redirectURL": "",
"headersSize": 433,
"bodySize": 0,
"_transferSize": 0
},
"cache": {},
"timings": {
"blocked": -1,
"dns": -1,
"connect": -1,
"send": 0,
"wait": 0,
"receive": 0,
"ssl": -1
},
"serverIPAddress": "204.2.145.184",
"connection": "989",
"pageref": "page_3"
}
1 answers
solution1
1 2017-02-13 08:51:24
In fact Chrome does served responses to second and third requests from cache. You need to look at entry.response.bodySize property.
Relevant excerpt from HAR specification :
bodySize [number] - Size of the received response body in bytes. Set to zero in case of responses coming from the cache (304). Set to -1 if the info is not available.
There is also interesting HAR Viewer GitHub issue . They use function below to determine whether response to request was served from cache:
HarModel.isCachedEntry = function(entry) {
var response = entry.response;
var resBodySize = response.bodySize > 0 ? response.bodySize : 0;
return (response.status == 304 || (resBodySize === 0 && response.content && response.content.size > 0));
};
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.
Related Question
Why chrome cached requests are taking time?
Nivo Slider Fails to Show 3rd Image in Chrome
why 2nd click action is not run when browser is Google Chrome
innerHTML strings aren't equal to the same string in javascript?
modifying 3rd party website locally for testing
3rd Party badges in Chrome DevTools: Colours
Why aren't canonical redirects working for me in Chrome?
Why aren't google chrome extensions auto updating?
Why does Chrome make a request for already cached image with max-age header?
Window.print() only displays all content on 2nd call
Related Tags