From 2955ddebc32837b66d9bacb4e925ad0ed0033168 Mon Sep 17 00:00:00 2001 From: Erlang/OTP Date: Tue, 23 Jun 2015 10:24:26 +0200 Subject: Prepare release --- erts/doc/src/notes.xml | 703 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 703 insertions(+) (limited to 'erts/doc') diff --git a/erts/doc/src/notes.xml b/erts/doc/src/notes.xml index 2574d45184..2d96ed6105 100644 --- a/erts/doc/src/notes.xml +++ b/erts/doc/src/notes.xml @@ -31,6 +31,709 @@

This document describes the changes made to the ERTS application.

+
Erts 7.0 + +
Fixed Bugs and Malfunctions + + +

+ Fix issuing with spaces and quoting in the arguments when + using erlang:open_port spawn_executable on windows. The + behavior now mimics how unix works. This change implies a + backwards incompatibility for how spawn_executable works + on windows.

+

+ *** POTENTIAL INCOMPATIBILITY ***

+

+ Own Id: OTP-11905

+ + +

+ Fix global call trace when hipe compiled code call beam + compiled functions. Tracing of beam functions should now + alway work regardless who the caller is.

+

+ Own Id: OTP-11939

+ + +

+ Correct cache alignment for ETS write_concurrency + locks to improve performance by reduced false sharing. + May increase memory footprint for tables with + write_concurrency.

+

+ Own Id: OTP-11974

+ + +

+ All possibly blocking operations in the fd/spawn and + terminal driver have been converted to non-blocking + operations. Before this fix it was possible for the VM to + be blocked for a long time if the entity consuming + stdout/stderr did not consume it fast enough.

+

+ Own Id: OTP-12239

+ + +

+ Add missing overhead for offheap binaries created from + external format. This fix can improve the garbage + collection of large binaries originating from + binary_to_term or messages from remote nodes.

+

+ Own Id: OTP-12554

+ + +

+ Ensure hashing of zero is consistent

+

Erlang treats positive and negative zero as + equal:

+

+ true = 0.0 =:= 0.0/-1

+

However, Erlangs hash functions: hash, phash and + phash2 did not reflect this behaviour. The hash values + produced by the different hash functions would not be + identical for positive and negative zero.

This + change ensures that hash value of positive zero is always + produced regardless of the signedness of the zero float, + i.e.,

+

+ true = erlang:phash2(0.0) =:= + erlang:phash2(0.0/-1)

+

+ Own Id: OTP-12641

+ + +

+ Ensure NIF term creation disallows illegal floating point + values and too long atoms. Such values will cause a NIF + to throw badarg exception when it returns.

+

+ Own Id: OTP-12655

+ + +

+ Fixed building of Map results from match_specs

+

+ A faulty "box-value" entered into the heap which could + cause a segmentation fault in the garbage collector if it + was written on a heap fragment.

+

+ Own Id: OTP-12656

+ + +

+ Fix hipe bug when matching a "writable" binary. The bug + has been seen to sometimes cause a failed binary matching + of a correct utf8 character, but other symptoms are also + possible.

+

+ Own Id: OTP-12667

+ + +

+ Keep dirty schedulers from waking other schedulers.

+

+ Own Id: OTP-12685

+ + +

+ Disable floating point exceptions if the VM is compiled + by clang/llvm. This is a known long-standing problem in + clang/llvm.

+

+ Own Id: OTP-12717

+ + +

+ Fix bug in file:sendfile for FreeBSD causing not + the entire file to be sent.

+

+ Own Id: OTP-12720

+ + +

+ Fix the broken Android support in erl_child_setup.c

+

+ Own Id: OTP-12751

+ + +

+ Faulty statistics reported by the fix_alloc + allocator.

+

+ Own Id: OTP-12766

+ + +

+ Fix two erts_snprintf() calls to correct sizes.

+

+ - run_erl.c (ose): Use the size of the signal type, not + its pointer. - erl_node_tables.c: Use the size of the + _BUFFER in erts_snprintf() to make sure we can use the + full space.

+

+ Own Id: OTP-12771

+ + +

+ Delayed memory allocations could be delayed an + unnecessarily long time.

+

+ Own Id: OTP-12812

+ + +

+ Make sure that timeouts on a pool of acceptors are + released in the correct order.

+

+ Own Id: OTP-12817

+ + +

+ Fix segmentation fault in module_info for deleted modules

+

+ Own Id: OTP-12820

+ + +

Fix garbage collection of literals in code purge

+

During code purging and check_process_code, the + checking of the binary reference embedded in the match + binary state was omitted for the tracing tests. This + would cause the binary match state to reference + deallocated memory.

+

+ Own Id: OTP-12821

+ + +

+ A bug has been corrected for gen_tcp:close so when + {linger,{true,0}} is in effect it does not wait for data + in the driver queue to transfer out before closing the + port. Bug fix by Rory Byrne.

+

+ Own Id: OTP-12840

+ + +

+ The documentation of the driver callback start() + erroneously stated that a return value of + ERL_DRV_ERROR_ERRNO caused the error value to be + passed via erl_errno when it should have been + errno.

+

+ Own Id: OTP-12855

+ + +
+ + +
Improvements and New Features + + +

+ Add md5 and module entries to + ?MODULE:module_info/0/1 and remove obsolete entry + 'import'.

+

+ *** POTENTIAL INCOMPATIBILITY ***

+

+ Own Id: OTP-11940

+ + +

+ Debug function erlang:display/1 shows content of + binaries and bitstrings, not only the length.

+

+ Own Id: OTP-11941

+ + +

The time functionality of Erlang has been extended. + This both includes a new + API for time, as well as time warp + modes which alters the behavior of the system + when system time changes. You are strongly encouraged + to use the new API instead of the old API based on + erlang:now/0. + erlang:now/0 has been deprecated since it is and + forever will be a scalability bottleneck. For more + information see the Time and Time + Correction chapter of the ERTS User's + Guide.

+

Besides the API changes and time warp modes a lot of + scalability and performance improvements regarding time + management has been made internally in the runtime + system. Examples of such improvements are scheduler + specific timer wheels, scheduler specific BIF timer + management, parallel retrieval of monotonic time and + system time on systems with primitives that are not + buggy.

+

+ Own Id: OTP-11997

+ + +

erlang:function_exported(M, F, A) will now + return true if M:F/A refers to a BIF.

+

+ *** POTENTIAL INCOMPATIBILITY ***

+

+ Own Id: OTP-12099

+ + +

+ New BIF: erlang:get_keys/0, lists all keys + associated with the process dictionary. Note: + erlang:get_keys/0 is auto-imported.

+

+ *** POTENTIAL INCOMPATIBILITY ***

+

+ Own Id: OTP-12151 Aux Id: seq12521

+ + +

+ Make distributed send of large messages yield to improve + real-time characteristics.

+

+ Own Id: OTP-12232

+ + +

+ Use high accuracy poll timeouts

+

+ Where available, use poll/select API's that can handle + time resolutions less than 1ms. In the cases where such + API's are not available the timeout is rounded up to the + nearest ms.

+

+ Own Id: OTP-12236

+ + +

+ The internal group to user_drv protocol has been changed + to be synchronous in order to guarantee that output sent + to a process implementing the user_drv protocol is + printed before replying. This protocol is used by the + standard_output device and the ssh application when + acting as a client.

+

+ This change changes the previous unlimited buffer when + printing to standard_io and other devices that end up in + user_drv to 1KB.

+

+ *** POTENTIAL INCOMPATIBILITY ***

+

+ Own Id: OTP-12240

+ + +

The previously introduced "eager check I/O" feature is + now enabled by default.

+

Eager check I/O can be disabled using the erl + command line argument: +secio false

+

Characteristics impact compared to previous + default:

Lower latency and smoother + management of externally triggered I/O operations. + A slightly reduced priority of externally triggered + I/O operations. +

+ Own Id: OTP-12254 Aux Id: OTP-12117

+ + +

+ Properly support maps in match_specs

+

+ Own Id: OTP-12270

+ + +

+ The notice that a crashdump has been written has been + moved to be printed before the crashdump is generated + instead of afterwords. The wording of the notice has also + been changed.

+

+ *** POTENTIAL INCOMPATIBILITY ***

+

+ Own Id: OTP-12292

+ + +

+ New function ets:take/2. Works the same as + ets:delete/2 but also returns the deleted + object(s).

+

+ Own Id: OTP-12309

+ + +

+ Tracing with cpu_timestamp option has been enabled on + Linux.

+

+ Own Id: OTP-12366

+ + +

+ ets:info/1,2 now contains information about whether + write_concurrency or read_concurrency is enabled.

+

+ Own Id: OTP-12376

+ + +

+ Improved usage of gcc's builtins for atomic memory + access. These are used when no other implementation of + atomic memory operations is available. For example, when + compiling for ARM when libatomic_ops is not + available.

+

+ The largest improvement will be seen when compiling with + a gcc with support for the __atomic_* + builtins (using a gcc of at least version 4.7), + but also when only the legacy __sync_* builtins + are available (using a gcc of at least version + 4.1) an improvement can be seen.

+

+ For more information see the "Atomic + Memory Operations and the VM" section of + $ERL_TOP/HOWTO/INSTALL.md.

+

+ Own Id: OTP-12383

+ + +

+ Introduce math:log2/1 function to math module.

+

+ Own Id: OTP-12411

+ + +

The documentation of the Abstract Format (in the ERTS + User's Guide) has been updated with types and + specification. (Thanks to Anthony Ramine.)

The + explicit representation of parentheses used in types of + the abstract format has been removed. Instead the new + functions erl_parse:type_inop_prec() and + erl_parse:type_preop_prec() can be used for + inserting parentheses where needed.

+

+ Own Id: OTP-12492

+ + +

+ Remove perfctr support

+

+ Development of perfctr in the linux kernel ceased in + 2010. The perfctr support code in the Erlang VM is thus + effectively dead code and therefor removed.

+

+ Own Id: OTP-12508

+ + +

zlib:inflateChunk/2 has been added. It works + like zlib:inflate/2, but decompresses no more data + than will fit in the buffer configured by + zlib:setBufSize/2.

+

+ Own Id: OTP-12548

+ + +

+ Use linear search for small select_val arrays

+

+ Own Id: OTP-12555

+ + +

+ New BIF ets:update_counter/4 with a default object as + argument, which will be inserted in the table if the key + was not found.

+

+ Own Id: OTP-12563

+ + +

+ Export missing types from zlib module

+

+ Own Id: OTP-12584

+ + +

+ Use persistent hashmaps for large Maps

Maps will use a + persistent hashmap implementation when the number of + pairs in a Map becomes sufficiently large. The change + will occur when a Map reaches 33 pairs in size but this + limit might change in the future.

+

The most significant impact for the user by this + change is speed, and to a lesser degree memory + consumption and introspection of Maps. Memory consumption + size is probalistic but lesser than gb_trees or + dict for instance. Any other impacts will be + transparent for the user except for the following + changes.

+

Semantics of Maps have changed in two incompatible + ways compared to the experimental implementation in OTP + 17:

Hashing of maps is done different by + erlang:phash2/1,2, erlang:phash/1 and + erlang:hash/2. Comparing two maps + with ==, /=, =<, <, >= and >, is done + different if the keys contain floating point + numbers. +

+ *** POTENTIAL INCOMPATIBILITY ***

+

+ Own Id: OTP-12585

+ + +

+ Scalability improvement for erlang:make_ref/0, + and other functionality that create references. Each + scheduler now manage its own set of references. By this + no communication at all is needed when creating + references.

+

+ Previous implementation generated a strictly + monotonically increasing sequence of references + corresponding to creation time on the runtime system + instance. This is not the case with current + implementation. You can only expect reference to be + unique. The Erlang/OTP documentation has never mentioned + anything else but the uniqueness property, so this change + is fully compatible. The only reason we've + marked this as a potential incompatibility is since an + early draft for an Erlang specification mentions strict + monotonicity as a property.

+

+ If you need to create data with a strict monotonicity + property use erlang:unique_integer([monotonic]). + Do not use the deprecated erlang:now().

+

+ *** POTENTIAL INCOMPATIBILITY ***

+

+ Own Id: OTP-12610

+ + +

+ Enable different abort signal from heart

+

By using environment variable HEART_KILL_SIGNAL, heart + can now use a different signal to kill the old running + Erlang.

+

By default the signal is SIGKILL but SIGABRT may also + be used by setting environment variable: + HEART_KILL_SIGNAL=SIGABRT

+

+ Own Id: OTP-12613 Aux Id: seq12826

+ + +

+ Update autconf to latest version 2015-03-04

+

+ Own Id: OTP-12646

+ + +

+ Optimization of timers internally in the VM. This include + process timers (receive ... after), port timers + (driver_set_timer()) as well as BIF timers + (erlang:send_after()/erlang:start_timer()).

+

+ Each scheduler thread now has its own lock-free timer + service instead of one locked central service. This + dramatically improves performance of timer management on + systems with a large amount of schedulers and timers.

+

+ The timer service internal data structure has also been + optimized to be able to handle more timers than before. + That is, each timer service is by its self able to handle + more timers without dramatic performance loss than the + old centralized timer service.

+

+ The API of BIF timers has also been extended. Timeout + values are for example no longer limited to 32-bit + integers. For more information see the documentation of + erlang:start_timer/4, + erlang:send_after/4, + erlang:cancel_timer/2, + and erlang:read_timer/2.

+

+ Characteristics impact: Calls to the synchronous versions + of erlang:cancel_timer(), and + erlang:read_timer() may take substantially longer + time to complete than before. This occur when the timer + that is accessed is managed by a remote scheduler. You + typically want to use the new asynchronous option in + order to avoid blocking the calling process.

+

+ Own Id: OTP-12650 Aux Id: OTP-11997

+ + +

+ Specialize instructions from common assembler patterns

+

Specialize common instructions of rem, + band, minus and plus in the beam + loader. This will reduce the number of fetches and thus + lessen the instruction dispatch pressure during runtime + and speed up those operations in some common cases.

+

Specialize move patterns from x-registers to the stack + with a new move_window instruction. This change + will reduce instruction dispatch pressure.

+

+ Own Id: OTP-12690

+ + +

+ Fix cross compilation for Android.

+

+ Own Id: OTP-12693

+ + +

+ Fix incorrect use of autoconf macro AC_EGREP_CPP, which + could cause faulty configuration if run from a path + containing the string 'yes'.

+

+ Own Id: OTP-12706

+ + +

+ Minimal Java version is now 1.6

+

+ Own Id: OTP-12715

+ + +

+ Send format and args on process exit to error_logger

+

+ Previously, the emulator would generate a whole string + with values and call the error_logger passing + "~s~n". This changes it to a format string + containing ~p with the respective values as + arguments.

+

+ Own Id: OTP-12735

+ + +

+ Map error logger warnings to warning messages by default.

+

+ Own Id: OTP-12755

+ + +

+ Configure architecture ppc64le architecture as a ppc64

+

+ Own Id: OTP-12761

+ + +

+ Add function enif_raise_exception to allow a NIF + to raise an error exception with any type of reason.

+

+ Own Id: OTP-12770

+ + +

+ Optimized node table statistics retrieval.

+

+ Own Id: OTP-12777

+ + +

+ Map beam error logger warnings to warning messages by + default. Previously these messages were mapped to the + error channel by default.

+

+ Own Id: OTP-12781

+ + +

+ gen_tcp:shutdown/2 is now asynchronous

+

+ This solves the following problems with the old + implementation:

+

+ It doesn't block when the TCP peer is idle or slow. This + is the expected behaviour when shutdown() is called: the + caller needs to be able to continue reading from the + socket, not be prevented from doing so.

+

+ It doesn't truncate the output. The current version of + gen_tcp:shutdown/2 will truncate any outbound data in the + driver queue after about 10 seconds if the TCP peer is + idle of slow. Worse yet, it doesn't even inform anyone + that the data has been truncated: 'ok' is returned to the + caller; and a FIN rather than an RST is sent to the TCP + peer.

+

+ *** POTENTIAL INCOMPATIBILITY ***

+

+ Own Id: OTP-12797

+ + +

+ Introduced delayed node table GC. This in order to avoid + oscillation of entries in and out of the tables. The + oscillation caused unnecessary lock contention on the + table locks. The delay length can be set by passing the + +zdntgc + command line argument.

+

+ Characteristics impact: The tables can grow to very large + sizes with unused entries if the node is get huge amounts + of short lived connections from other nodes. This problem + can be alleviated by shortening the length of the delay + using the +zdntgc command line argument.

+

+ Own Id: OTP-12802

+ + +

Improved implementation of erlang:statistics(io) + in order to reduce contention between schedulers.

+

Characteristics impact: The actual call to + erlang:statistics(io) takes longer time to + complete, but the overall impact on the system is + improved.

+

+ Own Id: OTP-12842

+ + +

+ There are many cases where user code needs to be able to + distinguish between a socket that was closed normally and + one that was aborted. Setting the option + {show_econnreset, true} enables the user to receive + ECONNRESET errors on both active and passive sockets.

+

+ Own Id: OTP-12843

+ + +

+ Do not preallocate too large event pool

+

+ A default pool size of 4000 is too excessive for the + common case. This corresponds directly to the number of + threads in the system. Change + ERTS_TS_EV_ALLOC_DEFAULT_POOL_SIZE to 2048. Change + ERTS_TS_EV_ALLOC_POOL_SIZE to 32.

+

+ Own Id: OTP-12849

+ + +
+ +
+
Erts 6.4.1
Fixed Bugs and Malfunctions -- cgit v1.2.3