This document points at the most important improvments in Erlang/OTP 4.8
More detailed information can be found in the Release Notes.

ERTS-4.8

• Performance and other characteristics improvements
 
The BEAM emulator can now address 1 Gbyte of memory , the previous limit (and still for JAM) was 256 Mbyte.

The limit on number of ports is now dynamic and follows the number of available file descriptors.

The limit on number of ets-tables can now be configurated by the user.
 
 

• Enhanced support for debugging
 
Processes,  which exit abnormally can now be kept for inspection. Such processes are called zombies. The number of zombie processes to keep can be configured with the BIF erlang:system_flag(keep_zombies,N). The default is to keep 0 zombies.

The contents of the Erlang crash dump are improved and extended.
 
 

• Incompatibilities
 
The compiled BEAM modules have a new format. All modules must be recompiled before the can be used in the R5 BEAM system.

 Global groups can now be reconfigurated.

 
 New features regarding ets are implemented and also a new table type ordered_set, which keeps the objects in Erlang term order.

• General

The compiler now evaluates expressions at compile-time, when their values are known, and also eliminate dead code from IF and CASE expressions, when only one  branch can be selected.

A new construction has been added to the language. The match operator (i.e. the = operator) can now be used within patterns. For example, the following is now valid:

f({plus,X,Y}=T) -> {X+Y,T}.

This often makes it possible to avoid rebuilding a term which is already present but has no name, since it was matched with a complex pattern.
It also makes it possible to rewrite the construction:

f(X) when X == #rec{x=1, y=a} -> ...

as

f(#rec{x=1, y=a} = X) -> ...

In the absence of optimization for the former case, the later case is more efficient.
The new language feature uses no new addition to the virtual Erlang machine, which means that a compiled module using the new feature, can be used in an old Erlang release, if it is not incompatible for some other reason.
 
 

• BEAM specific enhancements
 
It is possible to get smaller object code and faster execution due to the following;
 
•  Faster execution of "fun's".
•  Dead code elimination.
• Removal of unreachable code.
•  Misc. other compiler optimizations.

 
The generated code is improved (smaller and faster), encode of complex
ASN.1 types is 300% faster than the previous version.

All valid notations of OBJECT IDENTIFIER values are now supported.
 
 
 

INETS-2.3

• INETS httpd server has improved security.
 
It is now possible to through one API store authentication data in either plain text files, dets, databases or mnesia tables. Read the documentation on mod_auth for the details.
The mod_security module introduces user authentication logging, blocking of users and security events. The details are explained in the new documentation for mod_security.

• Improved performace in the INETS httpd server.
 
Performance has been boosted since the last release of INETS (2.2.6).
Many internal functions has been rewritten and/or modified to give maximum performance. One new thing that should improve performance, is the support for If-Modified-Since and Last-Modified headers (see RFC 1945 or 2068).

• INETS httpd  supports CGI scripts on Windows.
 
This previous limitation to the CGI support is now eliminated and CGI scripts run both on Unix and Windows, both in mod_cgi and mod_include (SSI exec cgi/cmd directives).

The attach window changes faster between already  loaded modules.
A Record Editor is available in the attach window. The purpose is to make it more easier to change records and long variables.  "Go to line" and text search functionality are added in the attach window.

   It is now possible to edit the table entries.

• What it is:
An API towards SQL Databases.
• Supported standards:
ODBC, which is a kind of de facto standard for accessing SQL databses. It was developed by Microsoft.
• When to use it:
Use it if you need to communicate with an external SQL database.
• Supported platforms:
Solaris
Windows NT/95 (in R5B)

A concept of fragmented tables has been introduced in order to cope  with very large tables. The idea is to split a table into several more manageable fragments. Each fragment is implemented as a first clas Mnesia table and may be replicated, have indecies etc.as any other  table.

 
The record type can now be declared as a part of the generator declarations, table/2 and rule/2.

 Mnemosyne's internal query format has been changed in order to manage all kinds of Erlang expressions inside queries.

 Better precision in error messages.
 

IIOP 1.1 have been added as default protocol for Orber. Orber do not support all  the new data types, because the IDL compiler is not yet updated.  but all the headers are updated so the protocol works.
 IIOP 1.0 is still usable but you have to set a configuration variable giop_version to get it.

The omg.org prefix has been added to CosNaming and CosEvent specifications. This means that the IDL types for these two services now have changed and  are incompatible with previous release but the names are now according to  the CORBA standard.

A couple of name creation functions have been added to the naming library. These are not in the CosNaming standard but they are easier to use in the Erlang environment (this will not interfer with the compatibility to other ORB's).
 
 

 
A new backend which generates Java code according to the CORBA IDL to Java  mapping for communication with the Erlang distribution protocol have been added to IC. For the moment there are no support for the Erlang types Pid,  Ref, Port and Term but this will be added later.