2021-02-02 18:07:02 +01:00
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zmq_ctx_set(3)
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==============
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NAME
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----
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zmq_ctx_set - set context options
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SYNOPSIS
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--------
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*int zmq_ctx_set (void '*context', int 'option_name', int 'option_value');*
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DESCRIPTION
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-----------
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The _zmq_ctx_set()_ function shall set the option specified by the
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'option_name' argument to the value of the 'option_value' argument.
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The _zmq_ctx_set()_ function accepts the following options:
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ZMQ_BLOCKY: Fix blocky behavior
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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By default the context will block, forever, on a zmq_ctx_term call. The
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assumption behind this behavior is that abrupt termination will cause
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message loss. Most real applications use some form of handshaking to ensure
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applications receive termination messages, and then terminate the context
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with 'ZMQ_LINGER' set to zero on all sockets. This setting is an easier way
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to get the same result. When 'ZMQ_BLOCKY' is set to false, all new sockets
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are given a linger timeout of zero. You must still close all sockets before
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calling zmq_ctx_term.
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[horizontal]
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Default value:: true (old behavior)
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ZMQ_IO_THREADS: Set number of I/O threads
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The 'ZMQ_IO_THREADS' argument specifies the size of the 0MQ thread pool to
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handle I/O operations. If your application is using only the 'inproc'
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transport for messaging you may set this to zero, otherwise set it to at
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least one. This option only applies before creating any sockets on the
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context.
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[horizontal]
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Default value:: 1
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ZMQ_THREAD_SCHED_POLICY: Set scheduling policy for I/O threads
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The 'ZMQ_THREAD_SCHED_POLICY' argument sets the scheduling policy for
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internal context's thread pool. This option is not available on windows.
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Supported values for this option can be found in sched.h file,
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or at http://man7.org/linux/man-pages/man2/sched_setscheduler.2.html.
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This option only applies before creating any sockets on the context.
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[horizontal]
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Default value:: -1
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ZMQ_THREAD_PRIORITY: Set scheduling priority for I/O threads
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The 'ZMQ_THREAD_PRIORITY' argument sets scheduling priority for
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internal context's thread pool. This option is not available on windows.
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Supported values for this option depend on chosen scheduling policy.
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On Linux, when the scheduler policy is SCHED_OTHER, SCHED_IDLE or SCHED_BATCH, the OS scheduler
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2023-08-05 20:31:33 +02:00
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will not use the thread priority but rather the thread "nice value"; in such cases,
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if 'ZMQ_THREAD_PRIORITY' is set to a strictly positive value,
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2021-02-02 18:07:02 +01:00
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the system call "nice" will be used to set the nice value to -20 (max priority) instead of
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adjusting the thread priority (which must be zero for those scheduling policies).
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Details can be found in sched.h file, or at http://man7.org/linux/man-pages/man2/sched_setscheduler.2.html.
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This option only applies before creating any sockets on the context.
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[horizontal]
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Default value:: -1
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ZMQ_THREAD_AFFINITY_CPU_ADD: Add a CPU to list of affinity for I/O threads
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The 'ZMQ_THREAD_AFFINITY_CPU_ADD' argument adds a specific CPU to the affinity list for the internal
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context's thread pool. This option is only supported on Linux.
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This option only applies before creating any sockets on the context.
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The default affinity list is empty and means that no explicit CPU-affinity will be set on
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internal context's threads.
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[horizontal]
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Default value:: -1
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ZMQ_THREAD_AFFINITY_CPU_REMOVE: Remove a CPU to list of affinity for I/O threads
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The 'ZMQ_THREAD_AFFINITY_CPU_REMOVE' argument removes a specific CPU to the affinity list for the internal
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context's thread pool. This option is only supported on Linux.
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This option only applies before creating any sockets on the context.
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The default affinity list is empty and means that no explicit CPU-affinity will be set on
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internal context's threads.
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[horizontal]
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Default value:: -1
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ZMQ_THREAD_NAME_PREFIX: Set name prefix for I/O threads
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The 'ZMQ_THREAD_NAME_PREFIX' argument sets a numeric prefix to each thread
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created for the internal context's thread pool. This option is only supported on Linux.
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This option is useful to help debugging done via "top -H" or "gdb"; in case
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multiple processes on the system are using ZeroMQ it is useful to provide through
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this context option an application-specific prefix to distinguish ZeroMQ background
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threads that belong to different processes.
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This option only applies before creating any sockets on the context.
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[horizontal]
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Default value:: -1
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ZMQ_MAX_MSGSZ: Set maximum message size
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The 'ZMQ_MAX_MSGSZ' argument sets the maximum allowed size
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of a message sent in the context. You can query the maximal
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allowed value with linkzmq:zmq_ctx_get[3] using the
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'ZMQ_MAX_MSGSZ' option.
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[horizontal]
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Default value:: INT_MAX
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Maximum value:: INT_MAX
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ZMQ_ZERO_COPY_RECV: Specify message decoding strategy
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The 'ZMQ_ZERO_COPY_RECV' argument specifies whether the message decoder should
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use a zero copy strategy when receiving messages. The zero copy strategy can
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lead to increased memory usage in some cases. This option allows you to use the
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older copying strategy. You can query the value of this option with
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linkzmq:zmq_ctx_get[3] using the 'ZMQ_ZERO_COPY_RECV' option.
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NOTE: in DRAFT state, not yet available in stable releases.
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[horizontal]
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Default value:: 1
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ZMQ_MAX_SOCKETS: Set maximum number of sockets
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The 'ZMQ_MAX_SOCKETS' argument sets the maximum number of sockets allowed
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on the context. You can query the maximal allowed value with
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linkzmq:zmq_ctx_get[3] using the 'ZMQ_SOCKET_LIMIT' option.
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[horizontal]
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Default value:: 1023
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ZMQ_IPV6: Set IPv6 option
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~~~~~~~~~~~~~~~~~~~~~~~~~
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The 'ZMQ_IPV6' argument sets the IPv6 value for all sockets created in
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the context from this point onwards. A value of `1` means IPv6 is
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enabled, while `0` means the socket will use only IPv4. When IPv6 is
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enabled, a socket will connect to, or accept connections from, both
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IPv4 and IPv6 hosts.
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[horizontal]
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Default value:: 0
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RETURN VALUE
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------------
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The _zmq_ctx_set()_ function returns zero if successful. Otherwise it
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returns `-1` and sets 'errno' to one of the values defined below.
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ERRORS
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------
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*EINVAL*::
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The requested option _option_name_ is unknown.
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EXAMPLE
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-------
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.Setting a limit on the number of sockets
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----
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void *context = zmq_ctx_new ();
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zmq_ctx_set (context, ZMQ_MAX_SOCKETS, 256);
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int max_sockets = zmq_ctx_get (context, ZMQ_MAX_SOCKETS);
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assert (max_sockets == 256);
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----
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SEE ALSO
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--------
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linkzmq:zmq_ctx_get[3]
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linkzmq:zmq[7]
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AUTHORS
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-------
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This page was written by the 0MQ community. To make a change please
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read the 0MQ Contribution Policy at <http://www.zeromq.org/docs:contributing>.
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