Erlang 17.5发布引入控制进程默认字典大小的命令行参数：
Erlang/OTP 17.5 has been released
Written by Henrik, 01 Apr 2015
Some highlights of the release are:
ERTS: Added command line argument option for setting the initial size of process dictionaries.
源码变化参看： https://github.com/erlang/otp/commit/c7a07bf984739bcc679d800e5383c01e1d07ffa5
文档：https://github.com/erlang/otp/commit/89987ada3c997fd9f1e1f8c8ed73da0394bda4ee
这个+hpds参数默认是字典有10个槽位，由于典型的Erlang VM内有成千上万的进程，官方又不鼓励使用字典，因为破坏fp语义，所以这些默认的字典占用的内存是浪费掉了。 挑小了对于内存敏感的嵌入式机器还是挺可观的；调大了对字典性能有一定的提升。
祝玩得开心！
Erlang 17.5版本引入了inet_dist_{listen,connect}_options，对于结点间的互联socket可以有更精细的控制，RPC的时候性能可以微调：
raimo/inet_tcp_dist-priority-option/OTP-12476:
Document kernel inet_dist_{listen,connect}_options
Test kernel inet_dist_{listen,connect}_options
Implement kernel inet_dist_{listen,connect}_options
参看源码：https://github.com/erlang/otp/commit/14ddc5594d74979a15a256a41fba5f1297aeaa1a
随着Erlang集群和节点上千，节点之间的RPC的开销和延迟就会被放大. 因为每个节点间的互通都是通过tcp, 驱动上也都是gen_tcp所以理论上对于gen_tcp合用的参数都可以设置，在延迟和吞吐量之间来平衡。
祝玩得开心！
三月底，官网宣布Erlang 18RC1公测，参看 这里，按照惯例Erlang每年会出一个大版本，从R11开始到现在R18，7年时间我从Erlang的发展历程中见证了一个大型系统的演变过程。
Erlang/OTP 18.0-rc1 is available for testing.
This is an alpha release, which will be followed by a planned beta release in May and a final OTP 18.0 product release in June 2015.
18.0正式版本6月份会放出， 这个版本很值得期待的内容有以下几点, 参看 News From the OTP TEAM Berlin Erlang Factory Lite 2014
重点需要解决的：
当期亮点：
长期的：
对于这次预发布最大的亮点如下：
Some highlights of the release are:
dialyzer: The -dialyzer() attribute can be used for suppressing warnings in a module by specifying functions or warning options. It can also be used for requesting warnings in a module.
erts: The time functionality has been extended. This includes a new API for time, as well as “time warp” modes which alters the behavior when system time changes. You are strongly encouraged to use the new API instead of the old API based on erlang:now/0. erlang:now/0 has been deprecated since it will always be a scalability bottleneck. For more information see the Time and Time Correction chapter of the ERTS User’s Guide. Here is a link http://www.erlang.org/documentation/doc-7.0-rc1/erts-7.0/doc/html/time_correction.html
erts: Beside the API changes and time warp modes a lot of scalability and performance improvements regarding time management has been made. Examples are:
scheduler specific timer wheels,
scheduler specific BIF timer management,
parallel retrieval of monotonic time and system time on OS:es that support it.
erts: The previously introduced “eager check I/O” feature is now enabled by default.
erts/compiler: enhanced support for maps. Big maps new uses a HAMT (Hash Array Mapped Trie) representation internally which makes them more efficient. There is now also support for variables as map keys.
ssl: Remove default support for SSL-3.0 and added padding check for TLS-1.0 due to the Poodle vulnerability.
ssl: Remove default support for RC4 cipher suites, as they are consider too weak.
stdlib: Allow maps for supervisor flags and child specs
其中对定时器的API语义和使用方式做了重新定义，伸缩能力优化做了大量的工作，拆成基于每个调度器的，对于定时器密集型的业务会有很大的性能提升。
具体的参考：Erlang VM Developer Lukas Larsson 做的 演讲
这次解决了定时器的瓶颈，个人最期待的是Multiple poll sets, 这个解决了，性能就完美了！
祝玩的开心！
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