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Diffstat (limited to 'guide/internals.md')
| -rw-r--r-- | guide/internals.md | 52 |
1 files changed, 47 insertions, 5 deletions
diff --git a/guide/internals.md b/guide/internals.md index 3179b9f..0f8adc2 100644 --- a/guide/internals.md +++ b/guide/internals.md @@ -4,7 +4,38 @@ Internals Architecture ------------ -@todo Describe. +Cowboy is a lightweight HTTP server. + +It is built on top of Ranch. Please see the Ranch guide for more +informations. + +It uses only one process per connection. The process where your +code runs is the process controlling the socket. Using one process +instead of two allows for lower memory usage. + +It uses binaries. Binaries are more efficient than lists for +representing strings because they take less memory space. Processing +performance can vary depending on the operation. Binaries are known +for generally getting a great boost if the code is compiled natively. +Please see the HiPE documentation for more details. + +Because querying for the current date and time can be expensive, +Cowboy generates one `Date` header value every second, shares it +to all other processes, which then simply copy it in the response. +This allows compliance with HTTP/1.1 with no actual performance loss. + +One process for many requests +----------------------------- + +As previously mentioned, Cowboy only use one process per connection. +Because there can be more than one request per connection with the +keepalive feature of HTTP/1.1, that means the same process will be +used to handle many requests. + +Because of this, you are expected to make sure your process cleans +up before terminating the handling of the current request. This may +include cleaning up the process dictionary, timers, monitoring and +more. Lowercase header names ---------------------- @@ -30,8 +61,19 @@ capitalize_hook(Status, Headers, Body, Req) -> Req2. ``` -Efficiency considerations -------------------------- +Improving performance +--------------------- + +By default the maximum number of active connections is set to a +generally accepted big enough number. This is meant to prevent having +too many processes performing potentially heavy work and slowing +everything else down, or taking up all the memory. + +Disabling this feature, by setting the `{max_connections, infinity}` +protocol option, would give you greater performance when you are +only processing short-lived requests. + +Another option is to define platform-specific socket options that +are known to improve their efficiency. -@todo Mention that you need to cleanup in terminate especially if you -used the process dictionary, started timers, started monitoring... +Please see the Ranch guide for more information. |