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-rw-r--r--erts/doc/src/Makefile1
-rw-r--r--erts/doc/src/communication.xml89
-rw-r--r--erts/doc/src/driver_entry.xml16
-rw-r--r--erts/doc/src/erl.xml103
-rw-r--r--erts/doc/src/erl_driver.xml185
-rw-r--r--erts/doc/src/erlang.xml338
-rw-r--r--erts/doc/src/part.xml1
7 files changed, 598 insertions, 135 deletions
diff --git a/erts/doc/src/Makefile b/erts/doc/src/Makefile
index 91e823fdb1..89d7c85a86 100644
--- a/erts/doc/src/Makefile
+++ b/erts/doc/src/Makefile
@@ -77,6 +77,7 @@ XML_CHAPTER_FILES = \
inet_cfg.xml \
erl_ext_dist.xml \
erl_dist_protocol.xml \
+ communication.xml \
notes.xml \
notes_history.xml
diff --git a/erts/doc/src/communication.xml b/erts/doc/src/communication.xml
new file mode 100644
index 0000000000..6049123f6a
--- /dev/null
+++ b/erts/doc/src/communication.xml
@@ -0,0 +1,89 @@
+<?xml version="1.0" encoding="latin1" ?>
+<!DOCTYPE chapter SYSTEM "chapter.dtd">
+
+<chapter>
+ <header>
+ <copyright>
+ <year>2012</year><year>2012</year>
+ <holder>Ericsson AB. All Rights Reserved.</holder>
+ </copyright>
+ <legalnotice>
+ The contents of this file are subject to the Erlang Public License,
+ Version 1.1, (the "License"); you may not use this file except in
+ compliance with the License. You should have received a copy of the
+ Erlang Public License along with this software. If not, it can be
+ retrieved online at http://www.erlang.org/.
+
+ Software distributed under the License is distributed on an "AS IS"
+ basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ the License for the specific language governing rights and limitations
+ under the License.
+
+ </legalnotice>
+
+ <title>Communication in Erlang</title>
+ <prepared>Rickard Green</prepared>
+ <responsible></responsible>
+ <docno></docno>
+ <approved></approved>
+ <checked></checked>
+ <date>2012-12-03</date>
+ <rev>PA1</rev>
+ <file>communication.xml</file>
+ </header>
+ <p>Communication in Erlang is conceptually performed using
+ asynchronous signaling. All different executing entities
+ such as processes, and ports communicate via asynchronous
+ signals. The most commonly used signal is a message. Other
+ common signals are exit, link, unlink, monitor, demonitor
+ signals.</p>
+ <section>
+ <title>Passing of Signals</title>
+ <p>The amount of time that passes between a signal being sent
+ and the arrival of the signal at the destination is unspecified
+ but positive. If the receiver has terminated, the signal will
+ not arrive, but it is possible that it triggers another signal.
+ For example, a link signal sent to a non-existing process will
+ trigger an exit signal which will be sent back to where the link
+ signal originated from. When communicating over the distribution,
+ signals may be lost if the distribution channel goes down.</p>
+ <p>The only signal ordering guarantee given is the following. If
+ an entity sends multiple signals to the same destination entity,
+ the order will be preserved. That is, if <c>A</c> send
+ a signal <c>S1</c> to <c>B</c>, and later sends
+ the signal <c>S2</c> to <c>B</c>, <c>S1</c> is guaranteed not to
+ arrive after <c>S2</c>.</p>
+ </section>
+ <section>
+ <title>Synchronous Communication</title>
+ <p>Some communication is synchronous. If broken down into pieces,
+ a synchronous communication operation, consists of two asynchronous
+ signals. One request signal and one reply signal. An example of
+ such a synchronous communication is a call to <c>process_info/2</c>
+ when the first argument is not <c>self()</c>. The caller will send
+ an asynchronous signal requesting information, and will then
+ wait for the reply signal containing the requested information. When
+ the request signal reaches its destination the destination process
+ replies with the requested information.</p>
+ </section>
+ <section>
+ <title>Implementation</title>
+ <p>The implementation of different asynchronous signals in the
+ VM may vary over time, but the behavior will always respect this
+ concept of asynchronous signals being passed between entities
+ as described above.</p>
+ <p>By inspecting the implementation you might notice that some
+ specific signal actually gives a stricter guarantee than described
+ above. It is of vital importance that such knowledge about the
+ implementation is <em>not</em> used by Erlang code, since the
+ implementation might change at any time without prior notice.</p>
+ <p>Some example of major implementation changes:</p>
+ <list type="bulleted">
+ <item>As of ERTS version 5.5.2 exit signals to processes are truly
+ asynchronously delivered.</item>
+ <item>As of ERTS version 5.10 all signals from processes to ports
+ are truly asynchronously delivered.</item>
+ </list>
+ </section>
+</chapter>
+
diff --git a/erts/doc/src/driver_entry.xml b/erts/doc/src/driver_entry.xml
index f31b0cb18b..c37138e7b1 100644
--- a/erts/doc/src/driver_entry.xml
+++ b/erts/doc/src/driver_entry.xml
@@ -400,11 +400,11 @@ typedef struct erl_drv_entry {
<tag><marker id="driver_flags"/>int driver_flags</tag>
<item>
- <p>This field is used to pass driver capability information to the
- runtime system. If the <c>extended_marker</c> field equals
- <c>ERL_DRV_EXTENDED_MARKER</c>, it should contain <c>0</c> or
- driver flags (<c>ERL_DRV_FLAG_*</c>) ored bitwise. Currently
- the following driver flags exist:
+ <p>This field is used to pass driver capability and other
+ information to the runtime system. If the
+ <c>extended_marker</c> field equals <c>ERL_DRV_EXTENDED_MARKER</c>,
+ it should contain <c>0</c> or driver flags (<c>ERL_DRV_FLAG_*</c>)
+ ored bitwise. Currently the following driver flags exist:
</p>
<taglist>
<tag><c>ERL_DRV_FLAG_USE_PORT_LOCKING</c></tag>
@@ -427,6 +427,12 @@ typedef struct erl_drv_entry {
by the Erlang distribution (the behaviour has always been
required by drivers used by the distribution).
</item>
+ <tag><c>ERL_DRV_FLAG_NO_BUSY_MSGQ</c></tag>
+ <item>Disable busy port message queue functionality. For
+ more information, see the documentation of the
+ <seealso marker="erl_driver#erl_drv_busy_msgq_limits">erl_drv_busy_msgq_limits()</seealso>
+ function.
+ </item>
</taglist>
</item>
<tag>void *handle2</tag>
diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index 7cdb3a4dfe..99f2466d79 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -582,13 +582,71 @@
<seealso marker="erts_alloc">erts_alloc(3)</seealso> for
further information.</p>
</item>
+ <tag><c><![CDATA[+n Behavior]]></c></tag>
+ <item>
+ <p>Control behavior of signals to ports.</p>
+ <p>As of OTP-R16 signals to ports are truly asynchronously
+ delivered. Note that signals always have been documented as
+ asynchronous. The underlying implementation has, however,
+ previously delivered these signals synchronously. Correctly
+ written Erlang programs should be able to handle this without
+ any issues. Bugs in existing Erlang programs that make false
+ assumptions about signals to ports may, however, be tricky to
+ find. This switch has been introduced in order to at least
+ make it easier to compare behaviors during a transition period.
+ Note that <em>this flag is deprecated</em> as of its
+ introduction, and is scheduled for removal in OTP-R17.
+ <c>Behavior</c> should be one of the following characters:</p>
+ <taglist>
+ <tag><c>d</c></tag>
+ <item>The default. Asynchronous signals. A process that sends
+ a signal to a port may continue execution before the signal
+ has been delivered to the port.</item>
+ <tag><c>s</c></tag>
+ <item>Synchronous signals. A processes that sends a signal
+ to a port will not continue execution until the signal has
+ been delivered. Should <em>only</em> be used for testing and
+ debugging.</item>
+ <tag><c>a</c></tag>
+ <item>Asynchronous signals. As the default, but a processes
+ that sends a signal will even more frequently continue
+ execution before the signal has been delivered to the
+ port. Should <em>only</em> be used for testing and
+ debugging.</item>
+ </taglist>
+ </item>
<tag><marker id="max_processes"><c><![CDATA[+P Number]]></c></marker></tag>
<item>
- <p>Sets the maximum number of concurrent processes for this
- system. <c><![CDATA[Number]]></c> must be in the range 16..134217727.
- Default is 32768.</p>
- <p><em>NOTE</em>: It is possible to choose any value in the range
- but powers of 2 perform best.</p>
+ <p>Sets the maximum number of simultaneously existing processes for this
+ system. Valid range for <c>Number</c> is <c>[1024-134217727]</c></p>
+ <p><em>NOTE</em>: The actual maximum chosen may be much larger than
+ the <c>Number</c> passed. Currently the runtime system often,
+ but not always, chooses a value that is a power of 2. This might,
+ however, be changed in the future. The actual value chosen can be
+ checked by calling
+ <seealso marker="erlang#system_info_process_limit">erlang:system_info(process_limit)</seealso>.</p>
+ <p>The default value is <c>262144</c></p>
+ </item>
+ <tag><marker id="max_ports"><c><![CDATA[+Q Number]]></c></marker></tag>
+ <item>
+ <p>Sets the maximum number of simultaneously existing ports for this
+ system. Valid range for <c>Number</c> is <c>[1024-134217727]</c></p>
+ <p><em>NOTE</em>: The actual maximum chosen may be much larger than
+ the actual <c>Number</c> passed. Currently the runtime system often,
+ but not always, chooses a value that is a power of 2. This might,
+ however, be changed in the future. The actual value chosen can be
+ checked by calling
+ <seealso marker="erlang#system_info_port_limit">erlang:system_info(port_limit)</seealso>.</p>
+ <p>The default value used is normally <c>65536</c>. However, if
+ the runtime system is able to determine maximum amount of file
+ descriptors that it is allowed to open and this value is larger
+ than <c>65536</c>, the chosen value will increased to a value
+ larger or equal to the maximum amount of file descriptors that
+ can be opened.</p>
+ <p>Previously the environment variable <c>ERL_MAX_PORTS</c> was used
+ for setting the maximum number of simultaneously existing ports. This
+ environment variable is deprecated, and scheduled for removal in
+ OTP-R17, but can still be used.</p>
</item>
<tag><marker id="compat_rel"><c><![CDATA[+R ReleaseNumber]]></c></marker></tag>
<item>
@@ -597,21 +655,14 @@
default. This flags sets the emulator in compatibility mode
with an earlier Erlang/OTP release <c><![CDATA[ReleaseNumber]]></c>.
The release number must be in the range
- <c><![CDATA[7..<current release>]]></c>. This limits the emulator,
- making it possible for it to communicate with Erlang nodes
- (as well as C- and Java nodes) running that earlier release.</p>
- <p>For example, an R10 node is not automatically compatible
- with an R9 node, but R10 nodes started with the <c><![CDATA[+R 9]]></c>
- flag can co-exist with R9 nodes in the same distributed
- Erlang system, they are R9-compatible.</p>
+ <c><![CDATA[<current release>-2..<current release>]]></c>. This
+ limits the emulator, making it possible for it to communicate
+ with Erlang nodes (as well as C- and Java nodes) running that
+ earlier release.</p>
<p>Note: Make sure all nodes (Erlang-, C-, and Java nodes) of
a distributed Erlang system is of the same Erlang/OTP release,
or from two different Erlang/OTP releases X and Y, where
<em>all</em> Y nodes have compatibility mode X.</p>
- <p>For example: A distributed Erlang system can consist of
- R10 nodes, or of R9 nodes and R9-compatible R10 nodes, but
- not of R9 nodes, R9-compatible R10 nodes and "regular" R10
- nodes, as R9 and "regular" R10 nodes are not compatible.</p>
</item>
<tag><c><![CDATA[+r]]></c></tag>
<item>
@@ -934,6 +985,22 @@
without prior notice.
</p>
</item>
+ <tag><marker id="+spp"><c>+spp Bool</c></marker></tag>
+ <item>
+ <p>Set default scheduler hint for port parallelism. If set to
+ <c>true</c>, the VM will schedule port tasks when it by this can
+ improve the parallelism in the system. If set to <c>false</c>,
+ the VM will try to perform port tasks immediately and by this
+ improve latency at the expense of parallelism. If this
+ flag has not been passed, the default scheduler hint for port
+ parallelism is currently <c>false</c>. The default used can be
+ inspected in runtime by calling
+ <seealso marker="erlang#system_info_port_parallelism">erlang:system_info(port_parallelism)</seealso>.
+ The default can be overriden on port creation by passing the
+ <seealso marker="erlang#open_port_parallelism">parallelism</seealso>
+ option to
+ <seealso marker="erlang#open_port/2">open_port/2</seealso></p>.
+ </item>
<tag><marker id="sched_thread_stack_size"><c><![CDATA[+sss size]]></c></marker></tag>
<item>
<p>Suggested stack size, in kilowords, for scheduler threads.
@@ -1074,7 +1141,7 @@
</item>
</taglist>
</item>
- <tag><c><![CDATA[ERL_AFLAGS]]></c></tag>
+ <tag><marker id="ERL_AFLAGS"><c><![CDATA[ERL_AFLAGS]]></c></marker></tag>
<item>
<p>The content of this environment variable will be added to the
beginning of the command line for <c><![CDATA[erl]]></c>.</p>
@@ -1084,7 +1151,7 @@
the <c><![CDATA[-extra]]></c> section, i.e. the end of the command line
following after an <c><![CDATA[-extra]]></c> flag.</p>
</item>
- <tag><c><![CDATA[ERL_ZFLAGS]]></c> and <c><![CDATA[ERL_FLAGS]]></c></tag>
+ <tag><marker id="ERL_ZFLAGS"><c><![CDATA[ERL_ZFLAGS]]></c></marker> and <marker id="ERL_FLAGS"><c><![CDATA[ERL_FLAGS]]></c></marker></tag>
<item>
<p>The content of these environment variables will be added to the
end of the command line for <c><![CDATA[erl]]></c>.</p>
diff --git a/erts/doc/src/erl_driver.xml b/erts/doc/src/erl_driver.xml
index e16fd744c0..13f42a74a7 100644
--- a/erts/doc/src/erl_driver.xml
+++ b/erts/doc/src/erl_driver.xml
@@ -145,12 +145,20 @@
different threads. This, however, is not a problem for any
function in this API, since the emulator has control over
these threads.</p>
- <note>
- <p>Functions not explicitly documented as thread-safe are
- <em>not</em> thread-safe. Also note that some functions
+ <warning>
+ <p>Functions not explicitly documented as thread safe are
+ <em>not</em> thread safe. Also note that some functions
are <em>only</em> thread safe when used in a runtime
system with SMP support.</p>
- </note>
+ <p>A function not explicitly documented as thread safe may at
+ some point in time have a thread safe implementation in the
+ runtime system. Such an implementation may however change to
+ a thread <em>unsafe</em> implementation at any time <em>without
+ any notice</em> at all.
+ </p>
+ <p><em>Only use functions explicitly documented as thread safe
+ from arbitrary threads.</em></p>
+ </warning>
<p><marker id="lengthy_work"/>
As mentioned in the <seealso marker="#WARNING">warning</seealso> text at
the beginning of this document it is of vital importance that a driver callback
@@ -1529,16 +1537,81 @@ typedef struct ErlIOVec {
</desc>
</func>
<func>
+ <name><ret>void</ret><nametext>erl_drv_busy_msgq_limits(ErlDrvPort port, ErlDrvSizeT *low, ErlDrvSizeT *high)</nametext></name>
+ <fsummary>Set and get limits for busy port message queue</fsummary>
+ <desc>
+ <marker id="erl_drv_busy_msgq_limits"></marker>
+ <p>Sets and gets limits that will be used for controling the
+ busy state of the port message queue.</p>
+ <p>The port message queue will be set into a busy
+ state when the amount of command data queued on the
+ message queue reaches the <c>high</c> limit. The port
+ message queue will be set into a not busy state when the
+ amount of command data queued on the message queue falls
+ below the <c>low</c> limit. Command data is in this
+ context data passed to the port using either
+ <c>Port ! {Owner, {command, Data}}</c>, or
+ <c>port_command/[2,3]</c>. Note that these limits
+ only concerns command data that have not yet reached the
+ port. The <seealso marker="#set_busy_port">busy port</seealso>
+ feature can be used for data that has reached the port.</p>
+
+ <p>Valid limits are values in the range
+ <c>[ERL_DRV_BUSY_MSGQ_LIM_MIN, ERL_DRV_BUSY_MSGQ_LIM_MAX]</c>.
+ Limits will be automatically adjusted to be sane. That is,
+ the system will adjust values so that the low limit used is
+ lower or equal to the high limit used. By default the high
+ limit will be 8 kB and the low limit will be 4 kB.</p>
+
+ <p>By passing a pointer to an integer variable containing
+ the value <c>ERL_DRV_BUSY_MSGQ_READ_ONLY</c>, currently used
+ limit will be read and written back to the integer variable.
+ A new limit can be set by passing a pointer to an integer
+ variable containing a valid limit. The passed value will be
+ written to the internal limit. The internal limit will then
+ be adjusted. After this the adjusted limit will be written
+ back to the integer variable from which the new value was
+ read. Values are in bytes.</p>
+
+ <p>The busy message queue feature can be disabled either
+ by setting the <c>ERL_DRV_FLAG_NO_BUSY_MSGQ</c>
+ <seealso marker="driver_entry#driver_flags">driver flag</seealso>
+ in the <seealso marker="driver_entry">driver_entry</seealso>
+ used by the driver, or by calling this function with
+ <c>ERL_DRV_BUSY_MSGQ_DISABLED</c> as a limit (either low or
+ high). When this feature has been disabled it cannot be
+ enabled again. When reading the limits both of them
+ will be <c>ERL_DRV_BUSY_MSGQ_DISABLED</c>, if this
+ feature has been disabled.</p>
+
+ <p>Processes sending command data to the port will be suspended
+ if either the port is busy or if the port message queue is
+ busy. Suspended processes will be resumed when neither the
+ port is busy, nor the port message queue is busy.</p>
+
+ <p>For information about busy port functionality
+ see the documentation of the
+ <seealso marker="#set_busy_port">set_busy_port()</seealso>
+ function.</p>
+ </desc>
+ </func>
+ <func>
<name><ret>void</ret><nametext>set_busy_port(ErlDrvPort port, int on)</nametext></name>
<fsummary>Signal or unsignal port as busy</fsummary>
<desc>
<marker id="set_busy_port"></marker>
- <p>This function set and resets the busy status of the port. If
- <c>on</c> is 1, the port is set to busy, if it's 0 the port
- is set to not busy.</p>
- <p>When the port is busy, sending to it with <c>Port ! Data</c>
- or <c>port_command/2</c>, will block the port owner process,
- until the port is signaled as not busy.</p>
+ <p>This function set and unset the busy state of the port. If
+ <c>on</c> is non-zero, the port is set to busy, if it's zero the port
+ is set to not busy. You typically want to combine
+ this feature with the <seealso marker="#erl_drv_busy_msgq_limits">busy
+ port message queue</seealso> functionality.</p>
+ <p>Processes sending command data to the port will be suspended
+ if either the port is busy or if the port message queue
+ is busy. Suspended processes will be resumed when neither the
+ port is busy, nor the port message queue is busy. Command data
+ is in this context data passed to the port using either
+ <c>Port ! {Owner, {command, Data}}</c>, or
+ <c>port_command/[2,3]</c>.</p>
<p>If the
<seealso marker="driver_entry#driver_flags"><![CDATA[ERL_DRV_FLAG_SOFT_BUSY]]></seealso>
has been set in the
@@ -1547,6 +1620,10 @@ typedef struct ErlIOVec {
<seealso marker="erlang#port_command/3">port_command(Port, Data, [force])</seealso>
even though the driver has signaled that it is busy.
</p>
+ <p>For information about busy port message queue functionality
+ see the documentation of the
+ <seealso marker="#erl_drv_busy_msgq_limits">erl_drv_busy_msgq_limits()</seealso>
+ function.</p>
</desc>
</func>
<func>
@@ -1607,6 +1684,8 @@ typedef struct ErlIOVec {
<desc>
<marker id="driver_connected"></marker>
<p>This function returns the port owner process.</p>
+ <p>Note that this function is <em>not</em> thread-safe, not
+ even when the emulator with SMP support is used.</p>
</desc>
</func>
<func>
@@ -1634,22 +1713,32 @@ typedef struct ErlIOVec {
<tag><seealso marker="driver_entry#call">call</seealso></tag>
<item>Called from <c>erlang:port_call/3</c></item>
</taglist>
+ <p>Note that this function is <em>not</em> thread-safe, not
+ even when the emulator with SMP support is used.</p>
</desc>
</func>
<func>
- <name><ret>int</ret><nametext>driver_output_term(ErlDrvPort port, ErlDrvTermData* term, int n)</nametext></name>
+ <name><ret>int</ret><nametext>erl_drv_output_term(ErlDrvTermData port, ErlDrvTermData* term, int n)</nametext></name>
<fsummary>Send term data from driver to port owner</fsummary>
<desc>
- <marker id="driver_output_term"></marker>
+ <marker id="erl_drv_output_term"></marker>
<p>This functions sends data in the special driver term
- format. This is a fast way to deliver term data from a
- driver. It also needs no binary conversion, so the port
- owner process receives data as normal Erlang terms.</p>
+ format to the port owner process. This is a fast way to
+ deliver term data from a driver. It also needs no binary
+ conversion, so the port owner process receives data as
+ normal Erlang terms. The
+ <seealso marker="#erl_drv_send_term">erl_drv_send_term()</seealso>
+ functions can be used for sending to any arbitrary process
+ on the local node.</p>
+ <note><p>Note that the <c>port</c> parameter is <em>not</em>
+ an ordinary port handle, but a port handle converted using
+ <c>driver_mk_port()</c>.</p></note>
<p>The <c>term</c> parameter points to an array of
<c>ErlDrvTermData</c>, with <c>n</c> elements. This array
contains terms described in the driver term format. Every
term consists of one to four elements in the array. The
- term first has a term type, and then arguments.</p>
+ term first has a term type, and then arguments. The
+ <c>port</c> parameter specifies the sending port.</p>
<p>Tuple and lists (with the exception of strings, see below),
are built in reverse polish notation, so that to build a
tuple, the elements are given first, and then the tuple
@@ -1701,17 +1790,17 @@ ERL_DRV_EXT2TERM char *buf, ErlDrvUInt len
ErlDrvPort port = ...
ErlDrvTermData spec[] = {
ERL_DRV_ATOM, driver_mk_atom("tcp"),
- ERL_DRV_PORT, driver_mk_port(port),
+ ERL_DRV_PORT, driver_mk_port(drvport),
ERL_DRV_INT, 100,
ERL_DRV_BINARY, bin, 50, 0,
ERL_DRV_LIST, 2,
ERL_DRV_TUPLE, 3,
};
- driver_output_term(port, spec, sizeof(spec) / sizeof(spec[0]));
+ erl_drv_output_term(driver_mk_port(drvport), spec, sizeof(spec) / sizeof(spec[0]));
]]>
</code>
<p>Where <c>bin</c> is a driver binary of length at least 50
- and <c>port</c> is a port handle. Note that the <c>ERL_DRV_LIST</c>
+ and <c>drvport</c> is a port handle. Note that the <c>ERL_DRV_LIST</c>
comes after the elements of the list, likewise the
<c>ERL_DRV_TUPLE</c>.</p>
<p>The term <c>ERL_DRV_STRING_CONS</c> is a way to construct
@@ -1732,7 +1821,7 @@ ERL_DRV_EXT2TERM char *buf, ErlDrvUInt len
ERL_DRV_NIL,
ERL_DRV_LIST, 4
};
- driver_output_term(port, spec, sizeof(spec) / sizeof(spec[0]));
+ erl_drv_output_term(driver_mk_port(drvport), spec, sizeof(spec) / sizeof(spec[0]));
]]></code>
<p></p>
<code type="none"><![CDATA[
@@ -1742,7 +1831,7 @@ ERL_DRV_EXT2TERM char *buf, ErlDrvUInt len
ERL_DRV_STRING_CONS, (ErlDrvTermData)"123", 3,
ERL_DRV_STRING_CONS, (ErlDrvTermData)"abc", 3,
};
- driver_output_term(port, spec, sizeof(spec) / sizeof(spec[0]));
+ erl_drv_output_term(driver_mk_port(drvport), spec, sizeof(spec) / sizeof(spec[0]));
]]></code>
<p>The <c>ERL_DRV_EXT2TERM</c> term type is used for passing a
term encoded with the
@@ -1762,7 +1851,7 @@ ERL_DRV_EXT2TERM char *buf, ErlDrvUInt len
ERL_DRV_EXT2TERM, (ErlDrvTermData) binp->orig_bytes, binp->orig_size
ERL_DRV_TUPLE, 2,
};
- driver_output_term(port, spec, sizeof(spec) / sizeof(spec[0]));
+ erl_drv_output_term(driver_mk_port(drvport), spec, sizeof(spec) / sizeof(spec[0]));
]]></code>
<p>If you want to pass a binary and don't already have the content
of the binary in an <c>ErlDrvBinary</c>, you can benefit from using
@@ -1778,6 +1867,22 @@ ERL_DRV_EXT2TERM char *buf, ErlDrvUInt len
<c>ERL_DRV_EXT2TERM</c> term types were introduced in the 5.6
version of erts.
</p>
+ <p>This function is only thread-safe when the emulator with SMP
+ support is used.</p>
+ </desc>
+ </func>
+ <func>
+ <name><ret>int</ret><nametext>driver_output_term(ErlDrvPort port, ErlDrvTermData* term, int n)</nametext></name>
+ <fsummary>Send term data from driver to port owner</fsummary>
+ <desc>
+ <marker id="driver_output_term"></marker>
+ <warning><p><c>driver_output_term()</c> is deferred and will
+ be removed in the OTP-R17 release. Use
+ <seealso marker="#erl_drv_send_term">erl_drv_output_term()</seealso>
+ instead.</p>
+ </warning>
+ <p>The parameters <c>term</c> and <c>n</c> do the same thing
+ as in <seealso marker="#erl_drv_output_term">erl_drv_output_term()</seealso>.</p>
<p>Note that this function is <em>not</em> thread-safe, not
even when the emulator with SMP support is used.</p>
</desc>
@@ -1791,6 +1896,8 @@ ERL_DRV_EXT2TERM char *buf, ErlDrvUInt len
<c>string</c>. The atom is created and won't change, so the
return value may be saved and reused, which is faster than
looking up the atom several times.</p>
+ <p>Note that this function is <em>not</em> thread-safe, not
+ even when the emulator with SMP support is used.</p>
</desc>
</func>
<func>
@@ -1799,20 +1906,46 @@ ERL_DRV_EXT2TERM char *buf, ErlDrvUInt len
<desc>
<marker id="driver_mk_port"></marker>
<p>This function converts a port handle to the erlang term
- format, usable in the <c>driver_output_send</c> function.</p>
+ format, usable in the <seealso marker="#erl_drv_output_term">erl_drv_output_term()</seealso>, and <seealso marker="#erl_drv_send_term">erl_drv_send_term()</seealso> functions.</p>
+ <p>Note that this function is <em>not</em> thread-safe, not
+ even when the emulator with SMP support is used.</p>
</desc>
</func>
<func>
- <name><ret>int</ret><nametext>driver_send_term(ErlDrvPort port, ErlDrvTermData receiver, ErlDrvTermData* term, int n)</nametext></name>
+ <name><ret>int</ret><nametext>erl_drv_send_term(ErlDrvTermData port, ErlDrvTermData receiver, ErlDrvTermData* term, int n)</nametext></name>
<fsummary>Send term data to other process than port owner process</fsummary>
<desc>
- <marker id="driver_send_term"></marker>
+ <marker id="erl_drv_send_term"></marker>
<p>This function is the only way for a driver to send data to
<em>other</em> processes than the port owner process. The
<c>receiver</c> parameter specifies the process to receive
the data.</p>
+ <note><p>Note that the <c>port</c> parameter is <em>not</em>
+ an ordinary port handle, but a port handle converted using
+ <c>driver_mk_port()</c>.</p></note>
+ <p>The parameters <c>port</c>, <c>term</c> and <c>n</c> do the same thing
+ as in <seealso marker="#erl_drv_output_term">erl_drv_output_term()</seealso>.</p>
+ <p>This function is only thread-safe when the emulator with SMP
+ support is used.</p>
+ </desc>
+ </func>
+ <func>
+ <name><ret>int</ret><nametext>driver_send_term(ErlDrvPort port, ErlDrvTermData receiver, ErlDrvTermData* term, int n)</nametext></name>
+ <fsummary>Send term data to other process than port owner process</fsummary>
+ <desc>
+ <marker id="driver_send_term"></marker>
+ <warning><p><c>driver_send_term()</c> is deferred and will
+ be removed in the OTP-R17 release. Use
+ <seealso marker="#erl_drv_send_term">erl_drv_send_term()</seealso>
+ instead.</p>
+ <p>Also note that parameters of <c>driver_send_term()</c>
+ cannot be properly checked by the runtime system when
+ executed by arbitrary threads. This may cause the
+ <c>driver_send_term()</c> function not to fail when
+ it should.</p>
+ </warning>
<p>The parameters <c>term</c> and <c>n</c> do the same thing
- as in <seealso marker="#driver_output_term">driver_output_term</seealso>.</p>
+ as in <seealso marker="#erl_drv_output_term">erl_drv_output_term()</seealso>.</p>
<p>This function is only thread-safe when the emulator with SMP
support is used.</p>
</desc>
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index 5002c48ca1..1a97a84b42 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -854,10 +854,10 @@ b</pre>
</func>
<func>
<name name="exit" arity="2"/>
- <fsummary>Send an exit signal to a process</fsummary>
+ <fsummary>Send an exit signal to a process or a port</fsummary>
<desc>
<p>Sends an exit signal with exit reason <c><anno>Reason</anno></c> to
- the process <c><anno>Pid</anno></c>.</p>
+ the process or port identified by <c><anno>Pid</anno></c>.</p>
<p>The following behavior apply if <c><anno>Reason</anno></c> is any term
except <c>normal</c> or <c>kill</c>:</p>
<p>If <c><anno>Pid</anno></c> is not trapping exits, <c><anno>Pid</anno></c> itself will
@@ -2760,6 +2760,18 @@ os_prompt% </pre>
console window when spawning the port program.
(This option has no effect on other platforms.)</p>
</item>
+ <tag><marker id="open_port_parallelism"><c>{parallelism, Boolean}</c></marker></tag>
+ <item>
+ <p>Set scheduler hint for port parallelism. If set to <c>true</c>,
+ the VM will schedule port tasks when it by this can improve the
+ parallelism in the system. If set to <c>false</c>, the VM will
+ try to perform port tasks immediately and by this improving the
+ latency at the expense of parallelism. The default can be set on
+ system startup by passing the
+ <seealso marker="erl#+spp">+spp</seealso> command line argument
+ to <seealso marker="erl">erl(1)</seealso>.
+ </p>
+ </item>
</taglist>
<p>The default is <c>stream</c> for all types of port and
<c>use_stdio</c> for spawned ports.</p>
@@ -2812,10 +2824,11 @@ os_prompt% </pre>
the owning process using signals of the form
<c>{'EXIT', Port, PosixCode}</c>. See <c>file(3)</c> for
possible values of <c>PosixCode</c>.</p>
- <p><marker id="ERL_MAX_PORTS"></marker>
- The maximum number of ports that can be open at the same
- time is 1024 by default, but can be configured by
- the environment variable <c>ERL_MAX_PORTS</c>.</p>
+ <p>The maximum number of ports that can be open at the same
+ time can be configured by passing the
+ <seealso marker="erl#max_ports"><c>+Q</c></seealso>
+ command line flag to
+ <seealso marker="erl"><c>erl(1)</c></seealso>.</p>
</desc>
</func>
<func>
@@ -2873,10 +2886,10 @@ os_prompt% </pre>
<desc>
<p>Closes an open port. Roughly the same as
<c><anno>Port</anno> ! {self(), close}</c> except for the error behaviour
- (see below), and that the port does <em>not</em> reply with
- <c>{Port, closed}</c>. Any process may close a port with
- <c>port_close/1</c>, not only the port owner (the connected
- process).</p>
+ (see below), being synchronous, and that the port does
+ <em>not</em> reply with <c>{Port, closed}</c>. Any process may
+ close a port with <c>port_close/1</c>, not only the port owner
+ (the connected process).</p>
<p>For comparison: <c><anno>Port</anno> ! {self(), close}</c> fails with
<c>badarg</c> if <c><anno>Port</anno></c> cannot be sent to (i.e.,
<c><anno>Port</anno></c> refers neither to a port nor to a process). If
@@ -2888,8 +2901,12 @@ os_prompt% </pre>
<p>Note that any process can close a port using
<c><anno>Port</anno> ! {PortOwner, close}</c> just as if it itself was
the port owner, but the reply always goes to the port owner.</p>
- <p>In short: <c>port_close(Port)</c> has a cleaner and more
- logical behaviour than <c><anno>Port</anno> ! {self(), close}</c>.</p>
+ <p>As of OTP-R16 <c><anno>Port</anno> ! {PortOwner, close}</c> is truly
+ asynchronous. Note that this operation has always been
+ documented as an asynchronous operation, while the underlying
+ implementation has been synchronous. <c>port_close/1</c> is
+ however still fully synchronous. This due to its error
+ behavior.</p>
<p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not an open port or
the registered name of an open port.</p>
</desc>
@@ -2899,11 +2916,11 @@ os_prompt% </pre>
<fsummary>Send data to a port</fsummary>
<desc>
<p>Sends data to a port. Same as
- <c><anno>Port</anno> ! {self(), {command, Data}}</c> except for the error
- behaviour (see below). Any process may send data to a port
- with <c>port_command/2</c>, not only the port owner
- (the connected process).</p>
- <p>For comparison: <c><anno>Port</anno> ! {self(), {command, Data}}</c>
+ <c><anno>Port</anno> ! {PortOwner, {command, Data}}</c> except for the error
+ behaviour and being synchronous (see below). Any process may
+ send data to a port with <c>port_command/2</c>, not only the
+ port owner (the connected process).</p>
+ <p>For comparison: <c><anno>Port</anno> ! {PortOwner, {command, Data}}</c>
fails with <c>badarg</c> if <c><anno>Port</anno></c> cannot be sent to
(i.e., <c><anno>Port</anno></c> refers neither to a port nor to a process).
If <c><anno>Port</anno></c> is a closed port the data message disappears
@@ -2914,11 +2931,14 @@ os_prompt% </pre>
<p>Note that any process can send to a port using
<c><anno>Port</anno> ! {PortOwner, {command, <anno>Data</anno>}}</c> just as if it
itself was the port owner.</p>
- <p>In short: <c>port_command(<anno>Port</anno>, <anno>Data</anno>)</c> has a cleaner and
- more logical behaviour than
- <c><anno>Port</anno> ! {self(), {command, Data}}</c>.</p>
<p>If the port is busy, the calling process will be suspended
until the port is not busy anymore.</p>
+ <p>As of OTP-R16 <c><anno>Port</anno> ! {PortOwner, {command, Data}}</c> is
+ truly asynchronous. Note that this operation has always been
+ documented as an asynchronous operation, while the underlying
+ implementation has been synchronous. <c>port_command/2</c> is
+ however still fully synchronous. This due to its error
+ behavior.</p>
<p>Failures:</p>
<taglist>
<tag><c>badarg</c></tag>
@@ -2992,7 +3012,7 @@ os_prompt% </pre>
<fsummary>Set the owner of a port</fsummary>
<desc>
<p>Sets the port owner (the connected port) to <c><anno>Pid</anno></c>.
- Roughly the same as <c><anno>Port</anno> ! {self(), {connect, <anno>Pid</anno>}}</c>
+ Roughly the same as <c><anno>Port</anno> ! {Owner, {connect, <anno>Pid</anno>}}</c>
except for the following:</p>
<list type="bulleted">
<item>
@@ -3003,6 +3023,9 @@ os_prompt% </pre>
<c>{Port,connected}</c>.</p>
</item>
<item>
+ <p><c>port_connect/1</c> is synchronous, see below.</p>
+ </item>
+ <item>
<p>The new port owner gets linked to the port.</p>
</item>
</list>
@@ -3026,11 +3049,14 @@ os_prompt% </pre>
<c><anno>Port</anno> ! {PortOwner, {connect, <anno>Pid</anno>}}</c> just as if it
itself was the port owner, but the reply always goes to
the port owner.</p>
- <p>In short: <c>port_connect(<anno>Port</anno>, <anno>Pid</anno>)</c> has a cleaner and
- more logical behaviour than
- <c><anno>Port</anno> ! {self(),{connect,<anno>Pid</anno>}}</c>.</p>
+ <p>As of OTP-R16 <c><anno>Port</anno> ! {PortOwner, {connect, <anno>Pid</anno>}}</c> is
+ truly asynchronous. Note that this operation has always been
+ documented as an asynchronous operation, while the underlying
+ implementation has been synchronous. <c>port_connect/2</c> is
+ however still fully synchronous. This due to its error
+ behavior.</p>
<p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not an open port
- or the registered name of an open port, or if <c><anno>Pid</anno></c> is
+ or the registered name of an open port, or if <c>Pid</c> is
not an existing local pid.</p>
</desc>
</func>
@@ -3077,71 +3103,187 @@ os_prompt% </pre>
</func>
<func>
<name name="port_info" arity="1"/>
- <type name="port_info_result_item"/>
<fsummary>Information about a port</fsummary>
<desc>
<p>Returns a list containing tuples with information about
the <c><anno>Port</anno></c>, or <c>undefined</c> if the port is not open.
The order of the tuples is not defined, nor are all the
tuples mandatory.</p>
- <taglist>
- <tag><c>{registered_name, <anno>RegName</anno>}</c></tag>
- <item>
- <p><c><anno>RegName</anno></c> (an atom) is the registered name of
- the port. If the port has no registered name, this tuple
- is not present in the list.</p>
- </item>
- <tag><c>{id, <anno>Index</anno>}</c></tag>
- <item>
- <p><c><anno>Index</anno></c> (an integer) is the internal index of the
- port. This index may be used to separate ports.</p>
- </item>
- <tag><c>{connected, <anno>Pid</anno>}</c></tag>
- <item>
- <p><c><anno>Pid</anno></c> is the process connected to the port.</p>
- </item>
- <tag><c>{links, <anno>Pids</anno>}</c></tag>
- <item>
- <p><c><anno>Pids</anno></c> is a list of pids to which processes the
- port is linked.</p>
- </item>
- <tag><c>{name, <anno>String</anno>}</c></tag>
- <item>
- <p><c><anno>String</anno></c> is the command name set by
- <c>open_port</c>.</p>
- </item>
- <tag><c>{input, <anno>Bytes</anno>}</c></tag>
- <item>
- <p><c><anno>Bytes</anno></c> is the total number of bytes read from
- the port.</p>
- </item>
- <tag><c>{output, <anno>Bytes</anno>}</c></tag>
- <item>
- <p><c><anno>Bytes</anno></c> is the total number of bytes written to
- the port.</p>
- </item>
- <tag><c>{os_pid, <anno>OsPid</anno> | undefined}</c></tag>
- <item>
- <p><c> <anno>OsPid</anno></c> is the process identifier (or equivalent) of an OS process created with <c>open_port({spawn | spawn_executable, Command}, Options)</c>. If the port is not the result of spawning an OS process, the value is <c>undefined</c>.</p>
- </item>
- </taglist>
- <p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not a local port.</p>
+ <p>Currently the result will containt information about the
+ following <c>Item</c>s: <c>registered_name</c> (if the port has
+ a registered name), <c>id</c>, <c>connected</c>, <c>links</c>,
+ <c>name</c>, <c>input</c>, and <c>output</c>. For more information
+ about the different <c>Item</c>s, see
+ <seealso marker="#port_info/2">port_info/2</seealso>.</p>
+ <p>Failure: <c>badarg</c> if <c>Port</c> is not a local port
+ identifier, or an atom.</p>
</desc>
</func>
<func>
- <name name="port_info" arity="2"/>
- <type name="port_info_item"/>
- <type name="port_info_result_item"/>
- <fsummary>Information about a port</fsummary>
+ <name name="port_info" arity="2" clause_i="1"/>
+ <fsummary>Information about the connected process of a port</fsummary>
+ <desc>
+ <p><c><anno>Pid</anno></c> is the process identifier of the process
+ connected to the port.</p>
+ <p>If the port identified by <c><anno>Port</anno></c> is not open,
+ <c>undefined</c> is returned.</p>
+ <p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not a local
+ port identifier, or an atom.</p>
+ </desc>
+ </func>
+ <func>
+ <name name="port_info" arity="2" clause_i="2"/>
+ <fsummary>Information about the internal index of a port</fsummary>
+ <desc>
+ <p><c><anno>Index</anno></c> is the internal index of the port. This
+ index may be used to separate ports.</p>
+ <p>If the port identified by <c><anno>Port</anno></c> is not open,
+ <c>undefined</c> is returned.</p>
+ <p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not a local
+ port identifier, or an atom.</p>
+ </desc>
+ </func>
+ <func>
+ <name name="port_info" arity="2" clause_i="3"/>
+ <fsummary>Information about the input of a port</fsummary>
+ <desc>
+ <p><c><anno>Bytes</anno></c> is the total number of bytes
+ read from the port.</p>
+ <p>If the port identified by <c><anno>Port</anno></c> is not open,
+ <c>undefined</c> is returned.</p>
+ <p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not a local
+ port identifier, or an atom.</p>
+ </desc>
+ </func>
+ <func>
+ <name name="port_info" arity="2" clause_i="4"/>
+ <fsummary>Information about the links of a port</fsummary>
+ <desc>
+ <p><c><anno>Pids</anno></c> is a list of the process identifiers
+ of the processes that the port is linked to.</p>
+ <p>If the port identified by <c><anno>Port</anno></c> is not open,
+ <c>undefined</c> is returned.</p>
+ <p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not a local
+ port identifier, or an atom.</p>
+ </desc>
+ </func>
+ <func>
+ <name name="port_info" arity="2" clause_i="5"/>
+ <fsummary>Information about the locking of a port</fsummary>
<desc>
- <p>Returns information about <c><anno>Port</anno></c> as specified
- by <c><anno>Item</anno></c>, or <c>undefined</c> if the port is not open.
- Also, if <c>Item =:= registered_name</c> and the port has no
- registered name, <c>[]</c> is returned.</p>
- <p>For valid values of <c><anno>Item</anno></c>, and corresponding
- values of <c><anno>Result</anno></c>, see
- <seealso marker="#port_info/1">erlang:port_info/1</seealso>.</p>
- <p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not a local port.</p>
+ <p><c><anno>Locking</anno></c> is currently either <c>false</c>
+ (emulator without SMP support), <c>port_level</c> (port specific
+ locking), or <c>driver_level</c> (driver specific locking). Note
+ that these results are highly implementation specific and might
+ change in the future.</p>
+ <p>If the port identified by <c><anno>Port</anno></c> is not open,
+ <c>undefined</c> is returned.</p>
+ <p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not a local
+ port identifier, or an atom.</p>
+ </desc>
+ </func>
+ <func>
+ <name name="port_info" arity="2" clause_i="6"/>
+ <fsummary>Information about the memory size of a port</fsummary>
+ <desc>
+ <p><c><anno>Bytes</anno></c> is the total amount of memory,
+ in bytes, allocated for this port by the runtime system. Note
+ that the port itself might have allocated memory which is not
+ included in <c><anno>Bytes</anno></c>.</p>
+ <p>If the port identified by <c><anno>Port</anno></c> is not open,
+ <c>undefined</c> is returned.</p>
+ <p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not a local
+ port identifier, or an atom.</p>
+ </desc>
+ </func>
+ <func>
+ <name name="port_info" arity="2" clause_i="7"/>
+ <fsummary>Information about the monitors of a port</fsummary>
+ <desc>
+ <p><c><anno>Monitors</anno></c> represent processes that this port
+ is monitoring.</p>
+ <p>If the port identified by <c><anno>Port</anno></c> is not open,
+ <c>undefined</c> is returned.</p>
+ <p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not a local
+ port identifier, or an atom.</p>
+ </desc>
+ </func>
+ <func>
+ <name name="port_info" arity="2" clause_i="8"/>
+ <fsummary>Information about the name of a port</fsummary>
+ <desc>
+ <p><c><anno>Name</anno></c> is the command name set by
+ <seealso marker="#open_port/2">open_port/2</seealso>.</p>
+ <p>If the port identified by <c><anno>Port</anno></c> is not open,
+ <c>undefined</c> is returned.</p>
+ <p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not a local
+ port identifier, or an atom.</p>
+ </desc>
+ </func>
+ <func>
+ <name name="port_info" arity="2" clause_i="9"/>
+ <fsummary>Information about the OS pid of a port</fsummary>
+ <desc>
+ <p><c><anno>OsPid</anno></c> is the process identifier (or equivalent)
+ of an OS process created with
+ <seealso marker="#open_port/2">open_port({spawn | spawn_executable,
+ Command}, Options)</seealso>. If the port is not the result of spawning
+ an OS process, the value is <c>undefined</c>.</p>
+ <p>If the port identified by <c><anno>Port</anno></c> is not open,
+ <c>undefined</c> is returned.</p>
+ <p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not a local
+ port identifier, or an atom.</p>
+ </desc>
+ </func>
+ <func>
+ <name name="port_info" arity="2" clause_i="10"/>
+ <fsummary>Information about the output of a port</fsummary>
+ <desc>
+ <p><c><anno>Bytes</anno></c> is the total number of bytes written
+ to the port from Erlang processes using either
+ <seealso marker="#port_command/2">port_command/2</seealso>,
+ <seealso marker="#port_command/3">port_command/3</seealso>,
+ or <c><anno>Port</anno> ! {Owner, {command, Data}</c>.
+ </p>
+ <p>If the port identified by <c><anno>Port</anno></c> is not open,
+ <c>undefined</c> is returned.</p>
+ <p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not a local
+ port identifier, or an atom.</p>
+ </desc>
+ </func>
+ <func>
+ <name name="port_info" arity="2" clause_i="11"/>
+ <fsummary>Information about the parallelism hint of a port</fsummary>
+ <desc>
+ <p><c><anno>Boolean</anno></c> corresponds to the port parallelism
+ hint being used by this port. For more information see
+ the <seealso marker="#open_port_parallelism">parallelism</seealso>
+ option of <seealso marker="#open_port/2">open_port/2</seealso>.</p>
+ </desc>
+ </func>
+ <func>
+ <name name="port_info" arity="2" clause_i="12"/>
+ <fsummary>Information about the queue size of a port</fsummary>
+ <desc>
+ <p><c><anno>Bytes</anno></c> is the total amount of data,
+ in bytes, queued by the port using the ERTS driver queue
+ implementation.</p>
+ <p>If the port identified by <c><anno>Port</anno></c> is not open,
+ <c>undefined</c> is returned.</p>
+ <p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not a local
+ port identifier, or an atom.</p>
+ </desc>
+ </func>
+ <func>
+ <name name="port_info" arity="2" clause_i="13"/>
+ <fsummary>Information about the registered name of a port</fsummary>
+ <desc>
+ <p><c><anno>RegisteredName</anno></c> is the registered name of
+ the port. If the port has no registered name, <c>[]</c> is returned.</p>
+ <p>If the port identified by <c><anno>Port</anno></c> is not open,
+ <c>undefined</c> is returned.</p>
+ <p>Failure: <c>badarg</c> if <c><anno>Port</anno></c> is not a local
+ port identifier, or an atom.</p>
</desc>
</func>
<func>
@@ -3161,7 +3303,10 @@ os_prompt% </pre>
<name name="ports" arity="0"/>
<fsummary>All open ports</fsummary>
<desc>
- <p>Returns a list of all ports on the local node.</p>
+ <p>Returns a list of port identifiers corresponding to all the
+ ports currently existing on the local node.</p>
+
+ <p>Note that a port that is exiting, exists but is not open.</p>
</desc>
</func>
<func>
@@ -5494,19 +5639,40 @@ ok
<item>
<p>Returns a string containing the OTP release number.</p>
</item>
+ <tag><marker id="system_info_port_parallelism"><c>port_parallelism</c></marker></tag>
+ <item><p>Returns the default port parallelism scheduling hint used.
+ For more information see the
+ <seealso marker="erl#+spp">+spp</seealso> command line argument
+ of <seealso marker="erl">erl(1)</seealso>.</p></item>
+ <tag><c>process_count</c></tag>
+ <item>
+ <p>Returns the number of ports currently existing at
+ the local node as an integer. The same value as
+ <c>length(erlang:ports())</c> returns.</p>
+ </item>
+ <tag><marker id="system_info_port_limit"><c>port_limit</c></marker></tag>
+ <item>
+ <p>Returns the maximum number of simultaneously existing
+ ports at the local node as an integer. This limit
+ can be configured at startup by using the
+ <seealso marker="erl#max_ports"><c>+Q</c></seealso>
+ command line flag of
+ <seealso marker="erl"><c>erl(1)</c></seealso>.</p>
+ </item>
<tag><c>process_count</c></tag>
<item>
<p>Returns the number of processes currently existing at
the local node as an integer. The same value as
<c>length(processes())</c> returns.</p>
</item>
- <tag><c>process_limit</c></tag>
+ <tag><marker id="system_info_process_limit"><c>process_limit</c></marker></tag>
<item>
- <p>Returns the maximum number of concurrently existing
+ <p>Returns the maximum number of simultaneously existing
processes at the local node as an integer. This limit
- can be configured at startup by using the command line
- flag <c>+P</c>, see
- <seealso marker="erts:erl#max_processes">erl(1)</seealso>.</p>
+ can be configured at startup by using the
+ <seealso marker="erl#max_processes"><c>+P</c></seealso>
+ command line flag of
+ <seealso marker="erl"><c>erl(1)</c></seealso>.</p>
</item>
<tag><c>procs</c></tag>
<item>
diff --git a/erts/doc/src/part.xml b/erts/doc/src/part.xml
index e27b722721..2c178556d4 100644
--- a/erts/doc/src/part.xml
+++ b/erts/doc/src/part.xml
@@ -31,6 +31,7 @@
<description>
<p>The Erlang Runtime System Application <em>ERTS</em>.</p>
</description>
+ <xi:include href="communication.xml"/>
<xi:include href="match_spec.xml"/>
<xi:include href="crash_dump.xml"/>
<xi:include href="alt_dist.xml"/>