snmpa_error_io(3erl) Erlang Module Definition snmpa_error_io(3erl)NAME
snmpa_error_io - Functions for Reporting SNMP Errors on stdio
DESCRIPTION
The module snmpa_error_io implements the snmp_error_report behaviour (see snmpa_error_report ) containing two callback functions which are
called in order to report SNMP errors.
This module provides a simple mechanism for reporting SNMP errors. Errors are written to stdout using the io module. It is provided as an
simple example.
This module needs to be explicitly configured, see snmpa_error and configuration parameters .
EXPORTS
config_err(Format, Args) -> void()
Types Format = string()
Args = list()
The function is called if an error occurs during the configuration phase, for example if a syntax error is found in a configuration
file.
Format and Args are as in io:format(Format, Args) .
user_err(Format, Args) -> void()
Types Format = string()
Args = list()
The function is called if a user related error occurs at run-time, for example if a user defined instrumentation function returns
erroneous.
Format and Args are as in io:format(Format, Args) .
Ericsson AB snmp 4.19 snmpa_error_io(3erl)
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pool(3erl) Erlang Module Definition pool(3erl)NAME
pool - Load Distribution Facility
DESCRIPTION
pool can be used to run a set of Erlang nodes as a pool of computational processors. It is organized as a master and a set of slave nodes
and includes the following features:
* The slave nodes send regular reports to the master about their current load.
* Queries can be sent to the master to determine which node will have the least load.
The BIF statistics(run_queue) is used for estimating future loads. It returns the length of the queue of ready to run processes in the
Erlang runtime system.
The slave nodes are started with the slave module. This effects, tty IO, file IO, and code loading.
If the master node fails, the entire pool will exit.
EXPORTS
start(Name) ->
start(Name, Args) -> Nodes
Types Name = atom()
Args = string()
Nodes = [node()]
Starts a new pool. The file .hosts.erlang is read to find host names where the pool nodes can be started. See section Files below.
The start-up procedure fails if the file is not found.
The slave nodes are started with slave:start/2,3 , passing along Name and, if provided, Args . Name is used as the first part of the
node names, Args is used to specify command line arguments. See slave(3erl) .
Access rights must be set so that all nodes in the pool have the authority to access each other.
The function is synchronous and all the nodes, as well as all the system servers, are running when it returns a value.
attach(Node) -> already_attached | attached
Types Node = node()
This function ensures that a pool master is running and includes Node in the pool master's pool of nodes.
stop() -> stopped
Stops the pool and kills all the slave nodes.
get_nodes() -> Nodes
Types Nodes = [node()]
Returns a list of the current member nodes of the pool.
pspawn(Mod, Fun, Args) -> pid()
Types Mod = Fun = atom()
Args = [term()]
Spawns a process on the pool node which is expected to have the lowest future load.
pspawn_link(Mod, Fun, Args) -> pid()
Types Mod = Fun = atom()
Args = [term()]
Spawn links a process on the pool node which is expected to have the lowest future load.
get_node() -> node()
Returns the node with the expected lowest future load.
FILES
.hosts.erlang is used to pick hosts where nodes can be started. See net_adm(3erl) for information about format and location of this file.
$HOME/.erlang.slave.out.HOST is used for all additional IO that may come from the slave nodes on standard IO. If the start-up procedure
does not work, this file may indicate the reason.
Ericsson AB stdlib 1.17.3 pool(3erl)