pool(3erl)

🦋 pool(3erl) — Erlang Module Definition 🦋

Hey bestie, welcome to the manual page for pool(3erl) 💖. This is the Erlang Module Definition for the load distribution facility, and we're gonna make it make sense. Periodt. ✨

🌸 NAME 🌸

pool — load distribution facility. 💅

✨ DESCRIPTION ✨

Okay so this module is literally a way to run a set of Erlang nodes as a pool of computational processors 🫶. It's organized as a master and a set of slave nodes, and it 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. Lowkey iconic. 🧚

The slave nodes are started with the slave(3erl) module. This effects terminal I/O, file I/O, and code loading 🎀.

⚠️ Heads up: if the master node fails, the entire pool exits. Not a drill, bestie. 😭

🔥 EXPORTS 🔥

🫶 attach(Node) 🫶

attach(Node) -> already_attached | attached

Types:

Node = node()

Ensures that a pool master is running and includes Node in the pool master's pool of nodes. Slay. ✨

💅 get_node() 💅

get_node() -> node()

Returns the node with the expected lowest future load. The main character node, tbh. 👑

🌈 get_nodes() 🌈

get_nodes() -> [node()]

Returns a list of the current member nodes of the pool. Squad goals. 🫶

🦋 pspawn(Mod, Fun, Args) 🦋

pspawn(Mod, Fun, Args) -> pid()

Types:

Mod = module()
Fun = atom()
Args = [term()]

Spawns a process on the pool node that is expected to have the lowest future load. ✨

🎀 pspawn_link(Mod, Fun, Args) 🎀

pspawn_link(Mod, Fun, Args) -> pid()

Types:

Mod = module()
Fun = atom()
Args = [term()]

Spawns and links to a process on the pool node that is expected to have the lowest future load. Linked bestie energy. 🫶

👑 start(Name) / start(Name, Args) 👑

start(Name) -> Nodes
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. The startup procedure fails if the file is not found. No file, no pool, bestie. 💀

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, and Args is used to specify command-line arguments. 🛠️

Access rights must be set so that all nodes in the pool have the authority to access each other. Set those permissions, queen. 👑

The function is synchronous and all the nodes, and all the system servers, are running when it returns a value. That's the whole point — when it says it's ready, it's ready. ✨

🛑 stop() 🛑

stop() -> stopped

Stops the pool and kills all the slave nodes. It's giving closing the group chat. 💀💅

🗂️ FILES 🗂️

• .hosts.erlang — used to pick hosts where nodes can be started. For information about the format and location of this file, see net_adm:host_file/0. 🏠
• $HOME/.erlang.slave.out.HOST — used for all extra I/O that can come from the slave nodes on standard I/O. If the startup procedure does not work, this file can indicate the reason. So if things are acting sus, check this file. 🔍

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Sign-off tea ☕: Ericsson AB · stdlib 4.3.1.3 · pool(3erl). That's the source/version footer, bestie — bye! 💅✨