On 9/5/19 5:52 AM, fansari wrote: > I ran a test where I start one download with curl and with short delay > (about 1s) I request the same content by another client. > > 1567673769.781 12123 xxx.xxx.0.1 TCP_MISS/200 15553655 ... HIER_NONE > 1567673769.782 13992 xxx.xxx.0.239 TCP_MISS/200 15553655 ... HIER_DIRECT > > From the documentation I found that there is a setting called > "collapsed_forwarding" which when enabled gives the behaviour we want to > achieve: let the first request finish with download and then handle the > others from squid cash. Regardless of the collapsed_forwarding setting, the second request never waits for the first request to finish downloading the response. Instead: * When collapsed forwarding is prohibited: There is no waiting at all. * When collapsed forwarding is allowed: The second request waits until the response headers arrive. > I am just wondering about one thing: I did not enable this setting (I also > tried to set it to "off" explicitly) and nevertheless it already behaves > this way. You cannot make that conclusion by examining v3-4 access log records. Latest (unreleased) Squids mark collapsed requests using a CF tag (e.g. TCP_CF_MISS): https://github.com/squid-cache/squid/commit/d2a6dcb > When I interpret the logs correctly the first line indicates a waiting and > the second shows the download. Not necessarily: 1. The first access.log record could be a cache hit (by the second transaction) of an in-progress download initiated by the first transaction. You build Squid with --enable-delay-pools which marks such transactions as misses after bug 1001 changes: https://bugs.squid-cache.org/show_bug.cgi?id=1001 2. The second access.log record can be a regular cache miss (by the first transaction). It just happened to end a bit later so it was logged second. You can check request:record mapping by looking at logged client IPs. > With "collapsed_forwarding on" it behaves in the same way as with "off". To > me it looks like as if the collapsing is used regardless whether it is > enabled or not. Yes, but probably because there are no collapsable (in Squid terminology) requests in your tests. To test collapsed forwarding, you need Squid to receive the second request _before_ Squid receives the response headers for the first request. HTH, Alex. _______________________________________________ squid-users mailing list squid-users@xxxxxxxxxxxxxxxxxxxxx http://lists.squid-cache.org/listinfo/squid-users
