Hello Thank you for your response. However, I'm still a bit fuzzy when it comes to the keepalive and timeout attribute.
I understand keepalive=On attribute by itself but in combination with timeout is where I'm unclear. In the scenario that I presented with following: - timeout=3600 keepalive=On attributes - backend server taking a long time processing the request sent by client ( note: no streaming any data from server yet since it's busy processing the request, let's say processing time on server is 4 hrs ) - OS settings are set to send TCP Keep alive packet in every 2 mins My guess: - With TCP keep alive probes sent and ACK between 'Apache httpd' machine and 'Backend server' machine, we can be assured that there's no inactive or idle TCP connection. - But, from the 'Apache Httpd' application point of view, it hasn't received the data from the server in 1 hr(3600), and therefore 'Apache Httpd' will initiate a timeout. When the 'Backend Server' is ready in 4 hrs to stream the response back, there's no ' Apache Httpd' client to receive the response. Please do correct me if I'm thinking this incorrectly, Appreciate all the help Thanks. On Wed, Oct 13, 2021 at 10:03 AM Dino Ciuffetti <d...@tuxweb.it> wrote: > The global "Timeout" parameter is needed to set the length of time Apache > httpd will wait for I/O in various circumstances. > https://httpd.apache.org/docs/2.4/mod/core.html#timeout > > > The "keepalive" attribute of ProxyPass can be used to fool your network > equipments (like intermediate firewalls) to mantain the tcp connection > between apache and its backends open even when no data is passing from and > to the wires. Some network equipment like firewalls tend to drop inactive > (silent) connections too early (from my experience ~30 min but your mileage > may vary). > > The "timeout" attribute of ProxyPass is the number of seconds Apache httpd > waits for data sent by / to the backend. So in your case apache will close > a inactive connection with the backend in 1hr, but while your backend > continue to stream data the connection will be kept open. Yes, it's a sort > of application timeout. > > There is also the "connectiontimeout" attribute of ProxyPass that will > consider a new TCP connection with the backend not valid if it takes the > specified time to complete (TCP SYN + SYN/ACK + ACK) so it can be retried > earlier. > > > > > 13 ottobre 2021 16:22, "Usha Nayak" <usha...@gmail.com > <usha...@gmail.com?to=%22usha%20nayak%22%20%3cusha...@gmail.com%3E>> > wrote: > > Hello > Need help in understanding the highlighted parameters: > ProxyPass "/example" "http://backend.example.com"; timeout=3600 > keepalive=On > keepalive parameter - As I understand relates to TCP or socket keep alive > probes that are sent to prevent idle connection. > [image: image.png] > My confusion is : > > Assuming the backend server takes 4 hrs to process a request and I have > 'keepalive on' in Apache httpd with the OS setting to send tcp probes every > 2 minutes. Backend server and Apache httpd are sending TCP keep alive > packets to indicate the socket connection is not idle. > > > - In this case, would the 'apache httpd' close the connection in 1 hr > ( timeout = 3600) because the 'apache httpd' didn't get the http data? Is > this timeout 'apache httpd' application timeout ? > > Appreciate help. > Thanks. > > > >
