From 856ca61301e66e44c6e93d4ca7a03d83aebf46d5 Mon Sep 17 00:00:00 2001 From: Steven Scott <42449819+stevenscott89@users.noreply.github.com> Date: Tue, 5 Mar 2019 16:15:07 -0800 Subject: [PATCH] Add buffer commentary --- doc.go | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/doc.go b/doc.go index dcce1a6..c6f4df8 100644 --- a/doc.go +++ b/doc.go @@ -151,6 +151,53 @@ // checking. The application is responsible for checking the Origin header // before calling the Upgrade function. // +// Buffers +// +// Connections buffer network input and output to reduce the number +// of system calls when reading or writing messages. +// +// Write buffers are also used for constructing WebSocket frames. See RFC 6455, +// Section 5 for a discussion of message framing. A WebSocket frame header is +// written to the network each time a write buffer is flushed to the network. +// Decreasing the size of the write buffer can increase the amount of framing +// overhead on the connection. +// +// The buffer sizes in bytes are specified by the ReadBufferSize and +// WriteBufferSize fields in the Dialer and Upgrader. The Dialer uses a default +// size of 4096 when a buffer size field is set to zero. The Upgrader reuses +// buffers created by the HTTP server when a buffer size field is set to zero. +// The HTTP server buffers have a size of 4096 at the time of this writing. +// +// The buffer sizes do not limit the size of a message that can be read or +// written by a connection. +// +// Buffers are held for the lifetime of the connection by default. If the +// Dialer or Upgrader WriteBufferPool field is set, then a connection holds the +// write buffer only when writing a message. +// +// Applications should tune the buffer sizes to balance memory use and +// performance. Increasing the buffer size uses more memory, but can reduce the +// number of system calls to read or write the network. In the case of writing, +// increasing the buffer size can reduce the number of frame headers written to +// the network. +// +// Some guidelines for setting buffer parameters are: +// +// Limit the buffer sizes to the maximum expected message size. Buffers larger +// than the largest message do not provide any benefit. +// +// Depending on the distribution of message sizes, setting the buffer size to +// to a value less than the maximum expected message size can greatly reduce +// memory use with a small impact on performance. Here's an example: If 99% of +// the messages are smaller than 256 bytes and the maximum message size is 512 +// bytes, then a buffer size of 256 bytes will result in 1.01 more system calls +// than a buffer size of 512 bytes. The memory savings is 50%. +// +// A write buffer pool is useful when the application has a modest number +// writes over a large number of connections. when buffers are pooled, a larger +// buffer size has a reduced impact on total memory use and has the benefit of +// reducing system calls and frame overhead. +// // Compression EXPERIMENTAL // // Per message compression extensions (RFC 7692) are experimentally supported