Potential Incompatibilities

This document contains a list of all potential incompatibilities between Erlang 5.2/OTP R9B and the previous version Erlang 5.1/OTP R8B, and is an extract from the release notes for the respective applications.

Compiler

• 'try' and 'cond' are keywords in R9 and must not be used as atom names or field names in records (unless they are single-quoted). In the R9 release, the compiler options 'disable_try' and 'disable_cond' can be used to allow 'try' and 'cond' to be used as in previous releases (to allow compilation of old Erlang code).
  The 'disable_try'/'disable_cond' options will be removed in the R10 release.
  (Own Id: OTP-4464)

Erts

• spawn_opt/4 used 0 as default value for fullsweep_after instead of the default value used by spawn/3, and spawn_link/3. This caused all processes spawned by spawn_opt/4 (e.g. all gen_servers) to allways use fullsweep if the fullsweep_after option wasn't explicitly set. spawn_opt/4 has now been changed to use the same default value as spawn/3, and spawn_link/3.
  (Own Id: OTP-4179)

• The format of the monitor messages has been changed. The Object field in the {'DOWN', MonitorReference, Type, Object, Info} messages is now always on the form {RegisteredName, NodeName} when erlang:monitor/2 has been called with a registered name (see erlang(3)).
  (Own Id: OTP-4311)
  (Aux Id: Seq7326)

• Comparisons between two ports or between two references were previously unstable and didn't conform to the Erlang specification. Comparisons between two pids didn't previously conform to the Erlang specification. The comparison between two pids, ports, or references has therefore been changed and is now stable, and does now conform to the Erlang specification.

  Cut from the Erlang specification:
  If t1 and t2 are both refs, both PIDs, or both ports, then t1 precedes t2 if and only if either
  * node(t1) precedes node(t2), or
  * node(t1) equals node(t2) and t1 was created before t2.

  
  (Own Id: OTP-4511)

Kernel

• The module 'erlang' is now preloaded. Customized start scripts have to be rebuilt.
  (Own Id: OTP-4433)

• os:find_executable/1 would return wrong return values ({ok,Name} or error) if given an absolute path name instead of the documented values (Name or false).
  (Own Id: OTP-4476)

Odbc

• New API that has an Erlang/OTP touch and feel instead of being a C-interface with Erlang syntax. The old interface is deprecated and will be removed in release R10.
  (Own Id: OTP-4498)

• API functions that became deprecated in version 0.9.1 has been removed.
  (Own Id: OTP-4499)

Os_mon

• Nodename is now used as key in loadtable (os_mon mib).
  (Own Id: OTP-4501)
  (Aux Id: seq7435, seq7549, seq7596)

Runtime_tools

• • Trace ports can now be opened on remote nodes
  • It is possible to use the local node as a "trace control node", i.e. trace only remote nodes.
  • The function dbg:i/0 now prints information about all traced nodes
  • Added function dbg:tracer/3 - same as tracer/2 but on the given node
  • Added function dbg:flush_trace_port/1 - same as flush_trace_port/0 but on the given node
  • Added function dbg:trace_port_control/2 - same as trace_port_control/1 but on the given node
  • Added function dbg:get_tracer/1 - same as get_tracer/0 but on the given node
  • Added function dbg:stop_clear/0 - same as stop/0 but also clears all trace patterns
  • Added functions ctp/0, ctpl/0 and ctpg/0 - clears trace patterns on all functions
  • (Incompatible) A tracer is no longer autmatically started on the local node. I.e. to start a tracer on the local node you must explicitly call dbg:tracer/0 or dbg:tracer/2.
  • (Incompatible) dbg:ln/0 now includes the local node if it is traced
  • (Incompatible) Return values from dbg:p/2 and dbg:tp/x are changed - the element {matched,N} is replaced by {matched,LocalNode,N}
  
  (Own Id: OTP-4346)

Stdlib

• The undocumented and deprecated module bplus_tree in stdlib has been removed.
  (Own Id: OTP-4468)

• The deprecated module 'unix' has been removed. (Used 'os' instead.)
  (Own Id: OTP-4470)