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dormando edited this page Jan 9, 2024 · 1 revision

Memcached 1.6.23 Release Notes

Date: 2024-1-9

Download

http://www.memcached.org/files/memcached-1.6.23.tar.gz

Overview

This release only affects the proxy code. The request dispatch API has been redone. See https://github.com/memcached/memcached/wiki/Proxy for full documentation of the API.

In this release please consider the new API SLIGHTLY EXPERIMENTAL. While a large effort has been made to validate the code, it is a big change. Please carefully test before deploying.

If you are new to the proxy, a new user friendly route library is being developed: https://github.com/memcached/memcached-proxylibs/tree/main/lib/routelib

PLEASE NOTE: The previous mcp.await and pool(request) call forms are being aggressively deprecated. The code will be removed in the next release of memcached. You will need to move your configuration scripts to the new API before upgrading again. We do not expect to have to do this again in the future.

This is being done to allow simplifying the internal code and unblock performance and stabilization features that the old API was preventing.

DEFAULT CHANGE: The proxy has, by default, used a single background thread for issuing IO to backend servers. This generally prevents scaling past 4 CPU cores, but reduces the number of TCP sockets in use and increases pipelining to backends.

As of this release the default is to issue backend IO directly from worker threads. This behavior can be tweaked both on a global or per-pool basis.

It is our goal to stabilize the proxy going forward, focusing on code cleanups and smaller changes from now on. We also aim to include the new routelib directly inside memcached in the next release to improve ease of use.

Fixes

  • proxy: add mcp.backend_use_iothread(bool) + bugfix
  • proxy: lua API version 2
  • proxy: add mcp.time_[real|mono]_millis()

New Features

Proxy API version 2:

  • Improved performance by allowing pre-calculations reused on each request
  • Improved performance by avoiding allocations at request time, preventing GC usage
  • Allow recursive function calls
  • Allow much easier future API expansion
  • Custom callbacks for every backend request issued

Contributors

The following people contributed to this release since 1.6.22.

Note that this is based on who contributed changes, not how they were done. In many cases, a code snippet on the mailing list or a bug report ended up as a commit with your name on it.

Note that this is just a summary of how many changes each person made which doesn't necessarily reflect how significant each change was. For details on what led up into a branch, either grab the git repo and look at the output of git log 1.6.22..1.6.23 or use a web view.

     5	dormando
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