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* sverker/erts/beautify-ifdef-DEBUG:
erts: Beautify away #ifdef DEBUG
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Add a more scalable ETS ordered_set implementation
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* raimo/receive-TOS-TCLASS/ERIERL-187/OTP-15145:
Elaborate the disclaimer for 'pktoptions'
Improve platform filter
Fix endianness bug for CMSG parsing
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* sverker/erts/robustify-dist-entry-states/OTP-15297:
erts: Refactor port dist_entry & conn_id into PRTSD
Remove ugly fail case macros
Consolidate distribution entry state transitions
erts: Fix bug in undocumented system_flag(scheduling_statistics)
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spelled out as "port specific data".
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* Make connection_id part of the distribution handle as {ConnId, DistEntry}
in order for BIFs to verify correct connection.
* Make distribution handle opaque to net_kernel.
* Remove some unsafe lockless reads of DistEntry.flags
* Change state ERTS_DE_STATE_EXITING to be more of an internal state that
prevents erts from enqueue, encode or schedule new data to be sent. Otherwise
it should behave like ERTS_DE_STATE_CONNECTED.
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* raimo/receive-TOS-TCLASS/ERIERL-187/OTP-15145:
Write testcases for recvtos and friends
Fix term buffer overflow bug
Fix documentation due to feedback
Implement socket option recvtos and friends
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* maint:
Improve trapping in lists:reverse/2
Fix unsafe use of lists:reverse/1
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* john/erts/improve-list-reverse-trapping/OTP-15199:
Improve trapping in lists:reverse/2
Fix unsafe use of lists:reverse/1
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If the process had more free space than reductions it could run a
lot longer than it was supposed to. It didn't honor the number of
reductions going in either, nor did it bump reductions when
returning its result or erroring out.
This commit also removes this function from a work function in
scheduler_SUITE as it's extremely sensitive to the number of
reductions spent in the test, causing
equal_and_high_with_part_time_max to fail on some machines.
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* maint:
Updated OTP version
Update release notes
Update version numbers
erts: Fix "Prevent inconsistent node lists" fix
Fix include-path regression caused by dd0a39c
Restore default SIGTERM behaviour for port programs
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* maint-21:
Updated OTP version
Update release notes
Update version numbers
erts: Fix "Prevent inconsistent node lists" fix
Fix include-path regression caused by dd0a39c
Restore default SIGTERM behaviour for port programs
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* sverker/enif-cancel-select/OTP-15095:
erts: Add ERL_NIF_SELECT_CANCEL flag for enif_select
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Uses port specific data out of bounds.
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into maint-21
* sverker/erts/fix-aborted-pending-connection-race/OTP-15296:
erts: Fix "Prevent inconsistent node lists" fix
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done in a31216200bdee2c04b3fb3ae5e26607674715c8a
that could cause a new pending connection to be incorrectly aborted.
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erl_child_setup program ignores TERM signals as of ERTS version
10.0 (cff8dce0). This setting was unfortunately inherited by
port programs. This commit restores handling of TERM signals
in port programs to the default behavior. That is, terminate the
process.
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"(void)result" will silence warning about unused variable
and compiler will optimize away such unused variables.
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* maint:
Update PCRE from version 8.41 to version 8.42
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* rickard/pcre-8.42/OTP-15217:
Update PCRE from version 8.41 to version 8.42
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* maint:
Updated OTP version
Update release notes
Update version numbers
kernel: Fix missing abort_connection in net_kernel
Prevent inconsistent node lists
Fix an endless rescheduling loop when a process is executing process_info(self(), ...)
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* maint-21:
Updated OTP version
Update release notes
Update version numbers
kernel: Fix missing abort_connection in net_kernel
Prevent inconsistent node lists
Fix an endless rescheduling loop when a process is executing process_info(self(), ...)
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* maint:
Fix an endless rescheduling loop when a process is executing process_info(self(), ...)
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Fix an endless rescheduling loop when a process is executing process_…
OTP-15275
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The current ETS ordered_set implementation can quickly become a
scalability bottleneck on multicore machines when an application updates
an ordered_set table from concurrent processes [1][2]. The current
implementation is based on an AVL tree protected from concurrent writes
by a single readers-writer lock. Furthermore, the current implementation
has an optimization, called the stack optimization [3], that can improve
the performance when only a single process accesses a table but can
cause bad scalability even in read-only scenarios. It is possible to
pass the option {write_concurrency, true} to ets:new/2 when creating an
ETS table of type ordered_set but this option has no effect for tables
of type ordered_set without this commit. The new ETS ordered_set
implementation, added by this commit, is only activated when one passes
the options ordered_set and {write_concurrency, true} to the ets:new/2
function. Thus, the previous ordered_set implementation (from here on
called the default implementation) can still be used in applications
that do not benefit from the new implementation. The benchmark results
on the following web page show that the new implementation is many times
faster than the old implementation in some scenarios and that the old
implementation is still better than the new implementation in some
scenarios.
http://winsh.me/ets_catree_benchmark/ets_ca_tree_benchmark_results.html
The new implementation is expected to scale better than the default
implementation when concurrent processes use the following ETS
operations to operate on a table:
delete/2, delete_object/2, first/1, insert/2 (single object),
insert_new/2 (single object), lookup/2, lookup_element/2, member/2,
next/2, take/2 and update_element/3 (single object).
Currently, the new implementation does not have scalable support for the
other operations (e.g., select/2). However, when these operations are
used infrequently, the new implantation may still scale better than the
default implementation as the benchmark results at the URL above shows.
Description of the New Implementation
----------------------------------
The new implementation is based on a data structure which is called the
contention adapting search tree (CA tree for short). The following
publication contains a detailed description of the CA tree:
A Contention Adapting Approach to Concurrent Ordered Sets
Journal of Parallel and Distributed Computing, 2018
Kjell Winblad and Konstantinos Sagonas
https://doi.org/10.1016/j.jpdc.2017.11.007
http://www.it.uu.se/research/group/languages/software/ca_tree/catree_proofs.pdf
A discussion of how the CA tree can be used as an ETS back-end can be
found in another publication [1]. The CA tree is a data structure that
dynamically changes its synchronization granularity based on detected
contention. Internally, the CA tree uses instances of a sequential data
structure to store items. The CA tree implementation contained in this
commit uses the same AVL tree implementation as is used for the default
ordered set implementation. This AVL tree implementation is reused so
that much of the existing code to implement the ETS operations can be
reused.
Tests
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The ETS tests in `lib/stdlib/test/ets_SUITE.erl` have been extended to
also test the new ordered_set implementation. The function
ets_SUITE:throughput_benchmark/0 has also been added to this file. This
function can be used to measure and compare the performance of the
different ETS table types and options. This function writes benchmark
data to standard output that can be visualized by the HTML page
`lib/stdlib/test/ets_SUITE_data/visualize_throughput.html`.
[1]
More Scalable Ordered Set for ETS Using Adaptation.
In Thirteenth ACM SIGPLAN workshop on Erlang (2014).
Kjell Winblad and Konstantinos Sagonas.
https://doi.org/10.1145/2633448.2633455
http://www.it.uu.se/research/group/languages/software/ca_tree/erlang_paper.pdf
[2]
On the Scalability of the Erlang Term Storage
In Twelfth ACM SIGPLAN workshop on Erlang (2013)
Kjell Winblad, David Klaftenegger and Konstantinos Sagonas
https://doi.org/10.1145/2505305.2505308
http://winsh.me/papers/erlang_workshop_2013.pdf
[3]
The stack optimization works by keeping one preallocated stack instance
in every ordered_set table. This stack is updated so that it contains
the search path in some read operations (e.g., ets:next/2). This makes
it possible for a subsequent ets:next/2 to avoid traversing some nodes
in some cases. Unfortunately, the preallocated stack needs to be flagged
so that it is not updated concurrently by several threads which cause
bad scalability.
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* rickard/dist-entry-gc-fix/OTP-15279:
Prevent inconsistent node lists
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If net_kernel "forgets" to abort a connection (as it currently might),
the garbage collection of a distribution entry could cause node lists
to enter an inconsistent state.
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* sverker/erts/ets-memstat-false-leak/ERL-720/OTP-15278:
erts: Refactor ets FixedDeletion allocations
erts: Fix ets memstat false leak of FixedDeletion
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Introduce a put_tuple2 instruction
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process_info(self(), ...)
It is possible that a process has to yield before completing process_info BIF when it runs out of reductions. If this BIF is called by the process itself, it does not send a signal but executes in the context of a process. If it has to yield, it turns F_LOCAL_SIGS_ONLY flag on, which means new signals won't be fetched from the outer message queue.
When the same process needs to execute dirty system code (e.g. dirty GC) it has to be run on a dirty scheduler. However signals enqueued into outer queue cause it to be rescheduled on a normal scheduler. F_LOCAL_SIGS_ONLY prevent outer queue signals delivery, creating an endless rescheduling loop.
This commit disengages F_LOCAL_SIG_ONLY if process needs to execute dirty code in order to complete signal delivery and allow process to be moved to dirty run queue.
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Fix bug in compact representation of float_to_list/2
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Implement socket options recvtclass, recvtos, recvttl and pktoptions.
Document the implemented socket options, new types and message formats.
The options recvtclass, recvtos and recvttl are boolean options that
when activated (true) for a socket will cause ancillary data to be
received through recvmsg(). That is for packet oriented sockets
(UDP and SCTP).
The required options for this feature were recvtclass and recvtos,
and recvttl was only added to test that the ancillary data parsing
handled multiple data items in one message correctly.
These options does not work on Windows since ancillary data
is not handled by the Winsock2 API.
For stream sockets (TCP) there is no clear connection between
a received packet and what is returned when reading data from
the socket, so recvmsg() is not useful. It is possible to get
the same ancillary data through a getsockopt() call with
the IPv6 socket option IPV6_PKTOPTIONS, on Linux named
IPV6_2292PKTOPTIONS after the now obsoleted RFC where it originated.
(unfortunately RFC 3542 that obsoletes it explicitly undefines
this way to get packet ancillary data from a stream socket)
Linux also has got a way to get packet ancillary data for IPv4
TCP sockets through a getsockopt() call with IP_PKTOPTIONS,
which appears to be Linux specific.
This implementation uses a flag field in the inet_drv.c socket
internal data that records if any setsockopt() call with recvtclass,
recvtos or recvttl (IPV6_RECVTCLASS, IP_RECVTOS or IP_RECVTTL)
has been activated. If so recvmsg() is used instead of recvfrom().
Ancillary data is delivered to the application by a new return
tuple format from gen_udp:recv/2,3 containing a list of
ancillary data tuples [{tclass,TCLASS} | {tos,TOS} | {ttl,TTL}],
as returned by recvmsg(). For a socket in active mode a new
message format, containing the ancillary data list, delivers
the data in the same way.
For gen_sctp the ancillary data is delivered in the same way,
except that the gen_sctp return tuple format already contained
an ancillary data list so there are just more possible elements
when using these socket options. Note that the active mode
message format has got an extra tuple level for the ancillary
data compared to what is now implemented gen_udp.
The gen_sctp active mode format was considered to be the odd one
- now all tuples containing ancillary data are flat,
except for gen_sctp active mode.
Note that testing has not shown that Linux SCTP sockets deliver
any ancillary data for these socket options, so it is probably
not implemented yet. Remains to be seen what FreeBSD does...
For gen_tcp inet:getopts([pktoptions]) will deliver the latest
received ancillary data for any activated socket option recvtclass,
recvtos or recvttl, on platforms where IP_PKTOPTIONS is defined
for an IPv4 socket, or where IPV6_PKTOPTIONS or IPV6_2292PKTOPTIONS
is defined for an IPv6 socket. It will be delivered as a
list of ancillary data items in the same way as for gen_udp
(and gen_sctp).
On some platforms, e.g the BSD:s, when you activate IP_RECVTOS
you get ancillary data tagged IP_RECVTOS with the TOS value,
but on Linux you get ancillary data tagged IP_TOS with the
TOS value. Linux follows the style of RFC 2292, and the BSD:s
use an older notion. For RFC 2292 that defines the IP_PKTOPTIONS
socket option it is more logical to tag the items with the
tag that is the item's, than with the tag that defines that you
want the item. Therefore this implementation translates all
BSD style ancillary data tags to the corresponding Linux style
data tags, so the application will only see the tags 'tclass',
'tos' and 'ttl' on all platforms.
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causing erlang:memory to report too much ets memory.
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Sometimes when building a tuple, there is no way to avoid an
extra `move` instruction. Consider this code:
make_tuple(A) -> {ok,A}.
The corresponding BEAM code looks like this:
{test_heap,3,1}.
{put_tuple,2,{x,1}}.
{put,{atom,ok}}.
{put,{x,0}}.
{move,{x,1},{x,0}}.
return.
To avoid overwriting the source register `{x,0}`, a `move`
instruction is necessary.
The problem doesn't exist when building a list:
%% build_list(A) -> [A].
{test_heap,2,1}.
{put_list,{x,0},nil,{x,0}}.
return.
Introduce a new `put_tuple2` instruction that builds a tuple in a
single instruction, so that the `move` instruction can be eliminated:
%% make_tuple(A) -> {ok,A}.
{test_heap,3,1}.
{put_tuple2,{x,0},{list,[{atom,ok},{x,0}]}}.
return.
Note that the BEAM loader already combines `put_tuple` and `put`
instructions into an internal instruction similar to `put_tuple2`.
Therefore the introduction of the new instruction will not speed up
execution of tuple building itself, but it will be less work for
the loader to load the new instruction.
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* maint:
ops.tab: Fix potentially unsafe optimization of raise/2
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The operands for the raise/2 instruction are almost always in x(2) and
x(1). Therefore the loader translates the raise/2 instruction to an
i_raise/0 instruction which uses the values in x(2) and x(1). If the
operands happens to be in other registers, the loader inserts move/2
instruction to move them to x(2) and x(1).
The problem is that x(3) is used as a temporary register when
generating the move/2 instructions. That is unsafe if the
Value operand for raise/2 is x(3).
Thus:
raise x(0) x(3)
will be translated to:
move x(0) x(3)
move x(3) x(1)
move x(3) x(2)
i_raise
The Trace will be written to both x(2) and x(1).
The current compiler will never use x(3) for the Value operand,
so there is no need to patch previous releases. But a future compiler
version might allocate registers differently.
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process_info(self(), ...)
It is possible that a process has to yield before completing process_info BIF when it runs out of reductions. If this BIF is called by the process itself, it does not send a signal but executes in the context of a process. If it has to yield, it turns F_LOCAL_SIGS_ONLY flag on, which means new signals won't be fetched from the outer message queue.
When the same process needs to execute dirty system code (e.g. dirty GC) it has to be run on a dirty scheduler. However signals enqueued into outer queue cause it to be rescheduled on a normal scheduler. F_LOCAL_SIGS_ONLY prevent outer queue signals delivery, creating an endless rescheduling loop.
This commit disengages F_LOCAL_SIG_ONLY if process needs to execute dirty code in order to complete signal delivery and allow process to be moved to dirty run queue.
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* maint:
Updated OTP version
Update release notes
Update version numbers
Fix missing 'in' trace events during 'running' trace
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