This document contains a list of potential incompatibilities between Erlang 5.5/OTP R11B (unpatched) and the previous version Erlang 5.4/OTP R10B (unpatched), and is an extract from the release notes for the respective applications.

Some of the potential incompatibilities listed below have been introduced in R10B patches, although as a general rule, this is avoided.

Note: This document was compiled at the time when R11B was released and does not list any potential incompatibilities introduced in R11B patches. If using a patched version of R11B, please refer to the README for the respective patches for information about additional potential incompatibilites.

Compiler

• 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.)

  Own Id: OTP-6058

Erts

• NOTE: The design of SMP support for drivers is ongoing. There will probably be incompatible driver changes (only affecting drivers run on the runtime system with SMP support) released as patches for R11B.

  Potential incompatibility: Previously, specific driver call-backs were always called from the same thread. This is not true in the runtime system with SMP support. Calls to call-backs will be made from different threads, e.g., two consecutive calls to exactly the same call-back can be made from two different threads. This will in most cases not be a problem. All calls to call-backs are synchronized, i.e., only one call-back will be called at a time.

  Own Id: OTP-6006 Aux Id: OTP-6095

• Linked-in driver modifications.

  • Linked-in drivers must be recompiled.

  • The refc field in the ErlDrvBinary type has been removed. The reference count can be accessed via API functions. For more information see the erl_driver(1) man page.

  Own Id: OTP-6095 Aux Id: OTP-6006

Inets

• The internal design of using blocking gen_tcp:recv with a timeout and retries resulted in code that was hard to get a good overview of, and ultimate led to situations where the client got the wrong answer or no answer at all. The errors where many times very timing dependent and mainly effected the chunk-related functions, so if you where lucky you probably would not have noticed. The internal design was changed to use gen_tcp active once semantics. The API is not effected except for the function ftp:quote/2 which now returns a list of strings (ftp result lines) where the line endings "\r\n" has been removed. This was the original intention for the return value of ftp:quote/2 but it was non trivial to make a good such solution with the old design and a compromise was made.

  Introduced in Inets 4.5

  Own Id: OTP-5623

• When generating dynamic HTTP response bodies the the default content-type is now set to "text/html" instead of "text/plain" which is more intuitive.

  Introduced in Inets 4.5

  Own Id: OTP-5626

• The ftp client now supports passive mode. Actually the ftp client will always try to use passive mode and if it fails it will use active mode instead. It is also possible to force the ftp client to use active mode, if that is desired, by calling ftp:force_active/1 this way you can get the old behavior.

  Introduced in Inets 4.4.1

  Own Id: OTP-5148

• The pipeline timeout was changed to be zero by default to avoid that people by accident would create connection processes that never dies and eats up the socket resources.

  Introduced in Inets 4.3

  Own Id: OTP-5442

Kernel

• Previously unlink/1 and erlang:demonitor/2 behaved completely asynchronous. This had one undesirable effect, though. You could never know when you were guaranteed not to be affected by a link that you had unlinked or a monitor that you had demonitored.

  The new behavior of unlink/1 and erlang:demonitor/2 can be viewed as two operations performed atomically. Asynchronously send an unlink signal or a demonitor signal, and ignore any future results of the link or monitor.

  NOTE: This change can cause some obscure code to fail which previously did not. For example, the following code might hang:

  	    Mon = erlang:monitor(process, Pid),
  	    %% ...
  	    exit(Pid, bang),
  	    erlang:demonitor(Mon),
  	    receive
  	        {'DOWN', Mon, process, Pid, _} -> ok
  	    %% We were previously guaranteed to get a down message
  	    %% (since we exited the process ourself), so we could
  	    %% in this case leave out:
  	    %% after 0 -> ok
  	    end,
  	    

  Own Id: OTP-5772

• Global no longer allows the registration of a process under more than one name. If the old (buggy) behavior is desired the Kernel application variable global_multi_name_action can be given the value allow.

  Own Id: OTP-5640 Aux Id: OTP-5603

• The auth module API is deprecated.

  Own Id: OTP-6037

• Several bug fixes and improvements in the global name registration facility (see global(3)):

  • the name resolving procedure did not always unlink no longer registered processes;
  • the global name server could sometimes hang when a nodedown was immediately followed by a nodeup;
  • global names were not always unregistered when a node went down;
  • it is now possible to set and delete locks at the same time as the global name server is resolving names--the handling of global locks has been separated from registration of global names;

  As of this version, global no longer supports nodes running Erlang/OTP R7B or earlier.

  Introduced in Kernel 2.10.11

  Own Id: OTP-5563

• The previously undocumented and UNSUPPORTED zlib module has been updated in an incompatible way and many bugs have been corrected. It is now also documented.

  Introduced in Kernel 2.10.11

  Own Id: OTP-5715

Megaco

• The old version info print function, format_versions/1, have been deprecated.

  Introduced in Megaco 3.2.7

  Own Id: OTP-5953

• The conn_info function once again returns the next transaction id.

  Introduced in Megaco 3.2.5

  Own Id: OTP-5887

  Aux Id: Seq 10184

• localControlDescriptor list of localParm now at least has to be of length 1.

  Introduced in Megaco 3.2.4

  Own Id: OTP-5882

• The ok return value from test_digit_event and eval_digit_map has been changed.

  Introduced in Megaco 3.2.3/3.2.2

  Own Id: OTP-5826 Aux Id: Seq 10085

• The (successful) return value from the test_digit_event and eval_digit_map has been changed.

  Introduced in Megaco 3.2

  Own Id: OTP-5750 Aux Id: Seq 10085

• The File argument to the function enable_trace no longer sets up dbg to write the trace events directly to file but instead to be written to a plain text file using io:format.

  Also enable_trace no longer accepts the argument {io, Verbosity}.

  Own Id: OTP-5447

  Introduced in Megaco 3.0.1

• Package number scheme (among other things) was changed in version 1 of the standard.

  Introduced in Megaco 3.0

  Own Id: OTP-5272

• The config property orig_pending_limit has been renamed to sent_pending_limit.

  Introduced in Megaco 3.0

  Own Id: OTP-5220

OS_Mon

• The behaviour of OS_Mon 2.0 is backwards compatible under normal operation, but has changed somewhat in error situations: The services do not terminate and the API functions do not raise exceptions in all cases where they did before. Also, in the case where a service does terminate, the exit reason may be different.

• The memsup part of the OS_Mon application has been made more stable. If there are (possibly temporary) problems collecting memory data, the interface functions (get_memory_data/0, get_system_memory_data/0) now do not fail, but return the previously collected value, if any, or a dummy value otherwise. Also, a warning message is printed.

  Introduced in OS_Mon 1.8

  Own Id: OTP-5798

SASL

• A new option {update_paths,Bool} has been added for release_handler:install_release/2. It indicates if all application code paths should be updated (Bool==true), or if only code paths for modified applications should be updated (Bool==false, default).

  release_handler:set_unpacked/2 now returns an error tuple if a specified application directory does not exist.

  Introduced in SASL 2.1

  Own Id: OTP-5761

SNMP

• [manager] The snmpm_network_interface behaviour has been updated (see inform_response and definition of the manager net if).

  Introduced in SNMP 4.5

  Own Id: OTP-5733

• [agent] The format of the info returned by the agent info retrieval function has been changed. The info can be converted to the old format by calling the old_info_format function.

  Introduced in SNMP 4.4

  Own Id: OTP-5666

SSL

• The state of a connection in active mode could be in a restrictive state, so that an internal tcp_closed message was incorrectly considered illegal, resulting in a premature termination of the connection process.

  Introduced in SSL 3.0.11

  Own Id: OTP-5972 Aux Id: seq10188

STDLIB

• ets:info/1 has been corrected to behave according to the documentation and return a list of tuples, not a tuple with tuples.

  Own Id: OTP-5639

• Corrected filelib:ensure_dir/1 which sometimes returned true and sometimes ok to always return ok when successful. This goes against the documentation which said true, but ok was judged to be a more logical return value.

  Own Id: OTP-5960 Aux Id: seq10240

• The functions lists:ukeysort/2 and lists:ukeymerge/3 have been changed in such a way that two tuples are considered equal if their keys match.

  For the sake of consistency, lists:usort/2 and lists:umerge/3 have been modified too: two elements are considered equal if they compare equal.

  The file_sorter module has been modified in a similar way: the unique option now applies to the key (keysort() and keymerge()) and the ordering function (the option {order, Order} ).

  Own Id: OTP-6019

• The public option has been removed from digraph:new/1. The reason is that several functions in the digraph module are implemented using multiple ETS accesses, which is not thread safe. (Thanks to Ulf Wiger.)

  Own Id: OTP-5985

• Referencing a so far undeclared record from the default value of some record declaration is from now on considered an error by the linter. It is also an error if the default value of a record declaration uses or binds a variable.

  Own Id: OTP-5878

• filelib:wildcard/2 was broken (it ignored its second argument).

  Also, filelib:wildcard("Filename") (where the argument does not contain any meta-characters) would always return ["Filename"]. Corrected so that an empty list will be returned if "Filename" does not actually exist. (Same correction in filelib:wildcard/2.) (This change is a slight incompatibility.)

  filelib:wildcard/1,2 will generate a different exception when given bad patterns such as "{a,". The exception used to be caused by exit(missing_delimiter) but is now erlang:error({badpattern,missing_delimiter}).

  Introduced in STDLIB 1.13.7

  Own Id: OTP-5523 Aux Id: seq9824

• gb_sets:del_element/2 was changed to do the same as gb_sets:delete_any/2 which was the original intention, not as gb_sets:delete/2. Code that relies on gb_sets:del_element/2 causing an error if the element does not exist must be changed to call gb_sets:delete/2 instead.

  The documentation was also updated to explicitly document functions that were only referred to as "aliases" of a documented function. Also, a list of all functions common to the gb_sets, sets, and ordsets was added.

  Introduced in STDLIB 1.13.3

  Own Id: OTP-5277