R16B is a major new release of Erlang/OTP.
Detailed information on changes can be fetched at
http://www.erlang.org/download/otp_src_R16B.readme
--- HIGHLIGHTS ----------------------------------------------------------
OTP-7786 == ssh ==
Added User Guide for the SSH application
OTP-9892 == erts ==
Process optimizations. The most notable:
-- New internal process table implementation allowing for
both parallel reads as well as writes. Especially read
operations have become really cheap. This reduce contention
in various situations. For example when, spawning processes,
terminating processes, sending messages, etc.
-- Optimizations of run queue management reducing contention.
-- Optimizations of process state changes reducing
contention.
These changes imply changes of the characteristics the
system. Most notable: changed timing in the system.
OTP-9974 == erts ==
Non-blocking code loading. Earlier when an Erlang module was
loaded, all other execution in the VM were halted while the
load operation was carried out in single threaded mode. Now
modules are loaded without blocking the VM. Processes may
continue executing undisturbed in parallel during the entire
load operation. The load operation is completed by making the
loaded code visible to all processes in a consistent way with
one single atomic instruction. Non-blocking code loading will
improve realtime characteristics when modules are
loaded/upgraded on a running SMP system.
OTP-10256 == inets ==
httpc: The HTTP client now supports HTTPS through proxies
OTP-10336 == erts ==
Major port improvements. The most notable:
-- New internal port table implementation allowing for both
parallel reads as well as writes. Especially read operations
have become really cheap.This reduce contention in various
situations. For example when, creating ports, terminating
ports, etc.
-- Dynamic allocation of port structures. This allow for a
much larger maximum amount of ports allowed as a default. The
previous default of 1024 has been raised to 65536. Maximum
amount of ports can be set using the +Q command line flag of
erl(1). The previously used environment variable
ERL_MAX_PORTS has been deprecated and scheduled for removal
in OTP-R17.
-- Major rewrite of scheduling of port tasks. Major benefits
of the rewrite are reduced contention on run queue locks, and
reduced amount of memory allocation operations needed. The
rewrite was also necessary in order to make it possible to
schedule signals from processes to ports.
-- Improved internal thread progress functionality for easy
management of unmanaged threads. This improvement was
necessary for the rewrite of the port task scheduling.
-- Rewrite of all process to port signal implementations in
order to make it possible to schedule those operations. All
port operations can now be scheduled which allows for reduced
lock contention on the port lock as well as truly
asynchronous communication with ports.
-- Optimized lookup of port handles from drivers.
-- Optimized driver lookup when creating ports.
-- Preemptable erlang:ports/0 BIF.
-- Improving responsiveness by bumping reductions for a
process calling a driver callback directly.
These changes imply changes of the characteristics of the
system. The most notable:
-- Order of signal delivery -- The previous implementation of
the VM has delivered signals from processes to ports in a
synchronous stricter fashion than required by the language.
As of ERTS version 5.10, signals are truly asynchronously
delivered. The order of signal delivery still adheres to the
requirements of the language, but only to the requirements.
That is, some signal sequences that previously always were
delivered in one specific order may now from time to time be
delivered in different orders. This may cause Erlang programs
that have made false assumptions about signal delivery order
to fail even though they previously succeeded. For more
information about signal ordering guarantees, see the chapter
on communication in the ERTS user's guide. The +n command
line flag of erl(1) can be helpful when trying to find
signaling order bugs in Erlang code that have been exposed by
these changes.
-- Latency of signals sent from processes to ports -- Signals
from processes to ports where previously always delivered
immediately. This kept latency for such communication to a
minimum, but it could cause lock contention which was very
expensive for the system as a whole. In order to keep this
latency low also in the future, most signals from processes
to ports are by default still delivered immediately as long
as no conflicts occur. Such conflicts include not being able
to acquire the port lock, but also include other conflicts.
When a conflict occur, the signal will be scheduled for
delivery at a later time. A scheduled signal delivery may
cause a higher latency for this specific communication, but
improves the overall performance of the system since it
reduce lock contention between schedulers. The default
behavior of only scheduling delivery of these signals on
conflict can be changed by passing the +spp command line flag
to erl(1). The behavior can also be changed on port basis
using the parallelism option of the open_port/2 BIF.
-- Execution time of the erlang:ports/0 BIF -- Since
erlang:ports/0 now can be preempted, the responsiveness of
the system as a whole has been improved. A call to
erlang:ports/0 may, however, take a much longer time to
complete than before. How much longer time heavily depends on
the system load.
-- Reduction cost of calling driver callbacks -- Calling a
driver callback is quite costly. This was previously not
reflected in reduction cost at all. Since the reduction cost
now has increased, a process performing lots of direct driver
calls will be scheduled out more frequently than before.
Potential incompatibilities:
-- driver_send_term() has been deprecated and has been
scheduled for removal in OTP-R17. Replace usage of
driver_send_term() with usage of erl_drv_send_term().
-- driver_output_term() has been deprecated and has been
scheduled for removal in OTP-R17. Replace usage of
driver_output_term() with usage of erl_drv_output_term().
-- The new function erl_drv_busy_msgq_limits() has been added
in order to able to control management of port queues.
The driver API version has been bumped to 2.1 from 2.0 due to
the above changes in the driver API.
OTP-10410 == asn1 ==
The options for the ASN.1 compiler has been drastically
simplified. The backend is chosen by using ber, per, or uper.
The options optimize, nif, and driver are no longer needed.
The old options will still work, but will issue a warning.
Another change is that generated encode/2 function will
always return a binary (some backends used to return an
iolist).
OTP-10588 == asn1 ==
The ASN.1 compiler will now always include necessary run-time
functions in the generated Erlang modules (except for
asn1rt_nif which is still neeeded). If the option 'inline' is
used the ASN.1 compiler will generate a warning. But if
'{inline,OutputFile}' is use, the ASN.1 compiler will refuse
to compile the file. (Use a .set.asn file if you need to
remove the output file.)
The 'BIT STRING' type will now be decoded as Erlang
bitstrings by default. Use the new legacy_bit_string option
to encode as lists of ones and zeroes. (The
compact_bit_string option still works as before.)
Open types are now always returned as binaries (when there is
no information allowing them to be decoded).
--- POTENTIAL INCOMPATIBILITIES -----------------------------------------
OTP-9052 == common_test ==
Removed depricated run_test program, use ct_run instead.
OTP-9881 == common_test ==
It is now possible to let a test specification include other
test specifications. Included specs can either be joined with
the source spec (and all other joined specs), resulting in
one single test run, or they can be executed in separate test
runs. Also, a start flag/option, join_specs, has been
introduced, to be used in combination with the spec option.
With join_specs, Common Test can be told to either join
multiple test specifications, or run them separately. Without
join_specs, the latter behaviour is default. Note that this
is a change compared to earlier versions of Common Test,
where specifications could only be joined. More information
can be found in the Running Tests chapter in the User's Guide
(see the Test Specifications section).
OTP-10117 == inviso ==
The inviso application has been removed.
OTP-10170 == erts pman ==
Tuple funs (deprecated in R15B) are no longer supported.
OTP-10195 == edoc ==
Since EDoc 0.7.7 (R14B02) separate values of union types can
be annotated. However, the parser has hitherto chosen not to
add the necessary parentheses due to backwards compatibility.
From this release on code traversing the output of
edoc_parser needs to take care of parentheses around separate
values of union types. Examples of such code are layout
modules and doclet modules.
OTP-10336 == erts ==
Major port improvements. The most notable:
-- New internal port table implementation allowing for both
parallel reads as well as writes. Especially read operations
have become really cheap.This reduce contention in various
situations. For example when, creating ports, terminating
ports, etc.
-- Dynamic allocation of port structures. This allow for a
much larger maximum amount of ports allowed as a default. The
previous default of 1024 has been raised to 65536. Maximum
amount of ports can be set using the +Q command line flag of
erl(1). The previously used environment variable
ERL_MAX_PORTS has been deprecated and scheduled for removal
in OTP-R17.
-- Major rewrite of scheduling of port tasks. Major benefits
of the rewrite are reduced contention on run queue locks, and
reduced amount of memory allocation operations needed. The
rewrite was also necessary in order to make it possible to
schedule signals from processes to ports.
-- Improved internal thread progress functionality for easy
management of unmanaged threads. This improvement was
necessary for the rewrite of the port task scheduling.
-- Rewrite of all process to port signal implementations in
order to make it possible to schedule those operations. All
port operations can now be scheduled which allows for reduced
lock contention on the port lock as well as truly
asynchronous communication with ports.
-- Optimized lookup of port handles from drivers.
-- Optimized driver lookup when creating ports.
-- Preemptable erlang:ports/0 BIF.
-- Improving responsiveness by bumping reductions for a
process calling a driver callback directly.
These changes imply changes of the characteristics of the
system. The most notable:
-- Order of signal delivery -- The previous implementation of
the VM has delivered signals from processes to ports in a
synchronous stricter fashion than required by the language.
As of ERTS version 5.10, signals are truly asynchronously
delivered. The order of signal delivery still adheres to the
requirements of the language, but only to the requirements.
That is, some signal sequences that previously always were
delivered in one specific order may now from time to time be
delivered in different orders. This may cause Erlang programs
that have made false assumptions about signal delivery order
to fail even though they previously succeeded. For more
information about signal ordering guarantees, see the chapter
on communication in the ERTS user's guide. The +n command
line flag of erl(1) can be helpful when trying to find
signaling order bugs in Erlang code that have been exposed by
these changes.
-- Latency of signals sent from processes to ports -- Signals
from processes to ports where previously always delivered
immediately. This kept latency for such communication to a
minimum, but it could cause lock contention which was very
expensive for the system as a whole. In order to keep this
latency low also in the future, most signals from processes
to ports are by default still delivered immediately as long
as no conflicts occur. Such conflicts include not being able
to acquire the port lock, but also include other conflicts.
When a conflict occur, the signal will be scheduled for
delivery at a later time. A scheduled signal delivery may
cause a higher latency for this specific communication, but
improves the overall performance of the system since it
reduce lock contention between schedulers. The default
behavior of only scheduling delivery of these signals on
conflict can be changed by passing the +spp command line flag
to erl(1). The behavior can also be changed on port basis
using the parallelism option of the open_port/2 BIF.
-- Execution time of the erlang:ports/0 BIF -- Since
erlang:ports/0 now can be preempted, the responsiveness of
the system as a whole has been improved. A call to
erlang:ports/0 may, however, take a much longer time to
complete than before. How much longer time heavily depends on
the system load.
-- Reduction cost of calling driver callbacks -- Calling a
driver callback is quite costly. This was previously not
reflected in reduction cost at all. Since the reduction cost
now has increased, a process performing lots of direct driver
calls will be scheduled out more frequently than before.
Potential incompatibilities:
-- driver_send_term() has been deprecated and has been
scheduled for removal in OTP-R17. Replace usage of
driver_send_term() with usage of erl_drv_send_term().
-- driver_output_term() has been deprecated and has been
scheduled for removal in OTP-R17. Replace usage of
driver_output_term() with usage of erl_drv_output_term().
-- The new function erl_drv_busy_msgq_limits() has been added
in order to able to control management of port queues.
The driver API version has been bumped to 2.1 from 2.0 due to
the above changes in the driver API.
OTP-10410 == asn1 ==
The options for the ASN.1 compiler has been drastically
simplified. The backend is chosen by using ber, per, or uper.
The options optimize, nif, and driver are no longer needed.
The old options will still work, but will issue a warning.
Another change is that generated encode/2 function will
always return a binary (some backends used to return an
iolist).
OTP-10417 == kernel sasl ==
It is no longer possible to have {Mod,Vsn} in the 'modules'
list in a .app file.
This was earlier possible, although never documented in the
.app file reference manual. It was however visible in the
documentation of application:load/[1,2], where the same term
as in a .app file can be used as the first argument.
The possibility has been removed since the Vsn part was never
used.
OTP-10451 == ssl ==
Remove filter mechanisms that made error messages backwards
compatible with old ssl but hid information about what
actually happened.
This does not break the documented API however other reason
terms may be returned, so code that matches on the reason
part of {error, Reason} may fail.
OTP-10490 == stdlib ==
If a child process fails in its start function, then the
error reason was earlier only reported as an error report
from the error_handler, and supervisor:start_link would only
return {error,shutdown}. This has been changed so the
supervisor will now return {error,{shutdown,Reason}}, where
Reason identifies the failing child and its error reason.
(Thanks to Tomas Pihl)
OTP-10523 == tools ==
A new function, cover:flush(Nodes), is added which will fetch
data from remote nodes without stopping cover on those nodes.
This is used by test_server and common_test when it is safe
to assume that the node will be terminated after the test
anyway. The purpose is to avoid processes crashing when
re-loading the original beam if the processes is still
running old code.
Remote nodes will now continue to count code coverage if the
connection to the main node is broken. Earlier, a broken
connection would cause the cover_server on the remote node to
die and thus any still cover compiled modules would cause
process crash when trying to insert cover data in ets tables
that used to exist on the cover_server. The new functionality
also involves synchronization with the main node if the nodes
are reconnected.
OTP-10588 == asn1 ==
The ASN.1 compiler will now always include necessary run-time
functions in the generated Erlang modules (except for
asn1rt_nif which is still neeeded). If the option 'inline' is
used the ASN.1 compiler will generate a warning. But if
'{inline,OutputFile}' is use, the ASN.1 compiler will refuse
to compile the file. (Use a .set.asn file if you need to
remove the output file.)
The 'BIT STRING' type will now be decoded as Erlang
bitstrings by default. Use the new legacy_bit_string option
to encode as lists of ones and zeroes. (The
compact_bit_string option still works as before.)
Open types are now always returned as binaries (when there is
no information allowing them to be decoded).
OTP-10613 == ssl ==
Removed deprecated function ssl:pid/0, it has been pointless
since R14 but has been keep for backwards compatibility.
OTP-10633 == erts ==
Erlang specification 4.7.3 defines max tuple size to 65535
elements It is now enforced to no more than 16777215 elements
(arity 24 bits)
Previous edge cases (28 bits) were not validated and could
cause undefined behaviour.
OTP-10647 == erts ==
The previous default of a maximum of 32768 simultaneous
processes has been raised to 262144. This value can be
changed using the the +P command line flag of erl(1). Note
that the value passed now is considered as a hint, and that
actual value chosen in most cases will be a power of two.
OTP-10812 == stdlib ==
filelib:wildcard("some/relative/path/*.beam", Path) would
fail to match any file. That is, filelib:wildcard/2 would not
work if the first component of the pattern did not contain
any wildcard characters. (A previous attempt to fix the
problem in R15B02 seems to have made matters worse.)
(Thanks to Samuel Rivas and Tuncer Ayaz.)
There is also an incompatible change to the Path argument. It
is no longer allowed to be a binary.
OTP-10872 == erts ==
As of ERTS-5.10/OTP-R16A node names passed in the EPMD
protocol are required to be encoded in UTF-8. Since EPMD
previously accepted latin1 encoded node names this is an
incompatibility. However, since Erlang nodes always have
required characters in node names to be 7-bit ASCII
characters (and still do require this), this incompatibility
should not effect anyone using EPMD as an Erlang Port Mapper
Daemon.
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