Highlights

This document lists some highlights of Erlang 5.5/OTP R11B (unpatched), compared to the previous version Erlang 5.4/OTP R10B, with focus on things not already released as R10B patches.

Note: This document was compiled at the time when R11B was released and does not list any features introduced in R11B patches.

## 1 SMP Support

The major news is the support for SMP (Symmetric MultiProcessing).

SMP is supported by most modern operating systems like Linux, Windows, Mac OSx, Solaris and is becoming more important now when dual processors, hyper-threading technology and multi-core systems are a reality.

With Erlang, most of the problems which occur in multi-threaded programs have been solved once and for all in the Erlang VM and do not have to be handled by the application programmers.

In the SMP version of the Erlang virtual machine, there can be many process schedulers running in separate OS threads. As default there will be as many schedulers as there are processors or processor cores on the system.

The SMP support is totally transparent for the Erlang programs. That is, there is no need to change or recompile existing programs. Programs with built-in assumptions about sequential execution must be rewritten in order to take advantage of the SMP support, however.

In this release, the Erlang VM supports SMP with focus on stability. There will follow a number of subsequent steps with necessary optimizations and support for more platforms.

The Erlang VM with SMP support has been tested on the following platforms:

- Solaris 10 sparc
- Suse Linux (SLES 9) x86
- Mac OSx PPC

Some promising benchmarks:

- Big
  700 Erlang processes that "ping" each other. That is, all processes send a message to and receive an acknowledgement from all other processes.
- Encode-decode
  16 Erlang processes performing encode/decode of typical telecom protocol messages independent of each other for a duration of ten minutes, the total number of decodes counted. Some of the processing involves calls to Erlang drivers which are not parallelized yet.

Sun Fire T2000 Server, Solaris 10, UltraSPARC T1 Processor which is an 8 core CPU with 4 threads per core. Comparison between single-threaded Erlang VM and Erlang SMP VM with 32 schedulers.

| no SMP | SMP 32
Big | 1 | 14
Encode-decode | 1 | 7

ADM Opteron: 2 dual core CPUs running Suse Linux Enterprise Server 9. Comparison between single-threaded Erlang VM and Erlang SMP VM with 4 schedulers.

| no SMP | SMP 4
Big | 1 | 5
Encode-decode | 1 | 3.6

Intel Xeon: 2 Hyper-threaded processors running Suse Linux Enterprise Server 9 Comparison between single-threaded Erlang VM and Erlang SMP VM with 4 schedulers.

| no SMP | SMP 4
Big | 1 | 2.5
Encode-decode | 1 | 3.7

AMD Athlon (tm): 64 X2 Dual Core Processor 4200+, 2x512Kb L2 Cache, Linux Fedora Core 5; 2.6.16-1.2096_FC5.

| no SMP | SMP 2
Big | 1 | 2.8
Encode-decode | 1 | 2.3

See ERTS Release Notes.

## 2 Erlang Language and Related Issues

- The `andalso` and `orelse` operators are now allowed to be used in guards. That also applies to match specifications. See Erlang Reference Manual.
- The BIF `is_record/3` can now be used in guards. Also, `is_record/3` can now be called without an `erlang:` module prefix for consistency with the other `is_*` functions. See erlang(3).
- The compiler options `ignore_try` and `ignore_cond`, which allowed code that used unquoted `try` or `cond` as atoms or record tags, has been removed. Old code that depended on the options need to be revised to have occurrences of `try` or `cond` as atom or record tags single-quoted. (Note: Although `cond` is a reserved keyword, there is no `cond` statement. It might be introduced in a future release.)
- (ERTS 5.4.8) The new `fun M:F/A` construct creates a fun that refers to the latest version of `M:F/A`. This syntax is meant to replace tuple funs `{M,F}` which have many problems. See Erlang Reference Manual.
- (ERTS 5.4.8) The new type test `is_function(Fun, Arity)` -- which may be used in guards -- test whether `Fun` is a fun that can be applied to `Arity` arguments. See erlang(3).

## 3 New Applications

### 3.1 Dialyzer

Dialyzer is a static analysis tool that identifies software discrepancies such as type errors, unreachable code, unnecessary tests, etc in single Erlang modules or entire (sets of) applications. See Dialyzer documentation.

### 3.2 Inviso

The Inviso application, together with some new extensions to Runtime_Tools, is aimed at providing features for efficient tracing of production Erlang/OTP systems:

- Distributed tracing - tracing on any number of Erlang nodes.
- Autostart - tracing during system start-up.
- Overload protection - mechanisms for suspending and later reactivating tracing, should an overload situation occur.
- Enhanced use of meta tracing.
- Trace cases - predefined specifications of what to trace.
- Off-line merging and formatting of log files.

Inviso is still under development. An easier-to-use trace tool, using the features listed above, is planned to be released as an R11B patch in Q3/Q4 2006. See Inviso documentation.

### 3.3 SSH

The SSH application is an Erlang implementation of the secure shell protocol. It is considered to be a beta release, meaning there can be changes made to the API before it reaches 1.0. See SSH documentation.

## 4 Existing Applications

### 4.1 Compiler

(Compiler 4.3.6) It is now possible to encrypt the debug information in Beam files. See beam_lib(3).

### 4.2 Debugger

(Debugger 2.0) The debugger can now handle the `try/catch` language construct.

### 4.3 Inets

The Erlang implementation of the TFTP procotcol, `tftp`, is now documented. See tftp(3).

### 4.4 Kernel

In Kernel 2.10.X, several bug fixes and improvements have been made in `global`, the global name registration facility. See Kernel Release Notes.

### 4.5 OS_Mon

(OS_Mon 2.0) The entire OS_Mon application (code and documentation) has been reviewed and consequently updated with the goal to make the application more robust, homogeneous and easier to configure. See OS_Mon Release Notes.

### 4.6 STDLIB

Added the `zip` module with functions for reading and creating zip archives. See zip(3).

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