diff --git a/Cargo.lock b/Cargo.lock
index 21a7c2a..43dc217 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2,11 +2,29 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "getrandom"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4567c8db10ae91089c99af84c68c38da3ec2f087c3f82960bcdbf3656b6f4d7"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
 [[package]]
 name = "gg-broadcast"
 version = "0.0.1"
 dependencies = [
  "nebkor-maelstrom",
+ "rand",
  "serde_json",
 ]
 
@@ -32,6 +50,12 @@ version = "1.0.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "49f1f14873335454500d59611f1cf4a4b0f786f9ac11f4312a78e4cf2566695b"
 
+[[package]]
+name = "libc"
+version = "0.2.155"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97b3888a4aecf77e811145cadf6eef5901f4782c53886191b2f693f24761847c"
+
 [[package]]
 name = "nebkor-maelstrom"
 version = "0.0.1"
@@ -41,6 +65,12 @@ dependencies = [
  "serde_repr",
 ]
 
+[[package]]
+name = "ppv-lite86"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.83"
@@ -59,6 +89,36 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
 [[package]]
 name = "ryu"
 version = "1.0.18"
@@ -123,3 +183,9 @@ name = "unicode-ident"
 version = "1.0.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b"
+
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
diff --git a/gg-broadcast/Cargo.toml b/gg-broadcast/Cargo.toml
index ed7d5d3..60f714d 100644
--- a/gg-broadcast/Cargo.toml
+++ b/gg-broadcast/Cargo.toml
@@ -8,3 +8,4 @@ license-file.workspace = true
 [dependencies]
 serde_json.workspace = true
 nebkor-maelstrom = { path = "../nebkor-maelstrom" }
+rand = "0.8.5"
diff --git a/gg-broadcast/src/main.rs b/gg-broadcast/src/main.rs
index 6201256..c648821 100644
--- a/gg-broadcast/src/main.rs
+++ b/gg-broadcast/src/main.rs
@@ -1,83 +1,131 @@
-use std::{collections::HashMap, rc::Rc, sync::Mutex};
+use std::{
+    collections::{HashMap, HashSet},
+    io::BufRead,
+    sync::{mpsc::channel, Arc, Mutex},
+    thread,
+    time::Duration,
+};
 
 use nebkor_maelstrom::{protocol::Payload, Body, Message, Node, Runner};
+use rand::Rng;
 
 fn main() {
-    let out = std::io::stdout().lock();
-    let input = std::io::stdin().lock();
+    let out = std::io::stdout();
+    let std_in = Arc::new(std::io::stdin());
+
+    let (tx, rx) = channel();
+    let input = tx.clone();
+
+    let i = thread::spawn(move || {
+        let g = std_in.lock();
+        for line in g.lines().map_while(Result::ok) {
+            if let Ok(msg) = serde_json::from_str::<Message>(&line) {
+                input.send(msg).unwrap();
+            }
+        }
+    });
 
     let node = BCaster::default();
-    let node = Rc::new(Mutex::new(node));
+    let node = Arc::new(Mutex::new(node));
 
-    let runner = Runner::new(out, node);
+    let runner = Runner::new(node, out);
+    let runner = &runner;
 
-    runner.run(input);
+    let g = thread::spawn(move || loop {
+        let millis = rand::thread_rng().gen_range(120..=180);
+        thread::sleep(Duration::from_millis(millis));
+        let body = Body::from_type("do_gossip");
+        let msg = Message {
+            body,
+            ..Default::default()
+        };
+        tx.send(msg).unwrap();
+    });
+
+    runner.run(rx);
+    let _ = i.join();
+    let _ = g.join();
 }
 
-type Store = HashMap<String, i64>;
-type Gossips = HashMap<u64, Message>;
-
 #[derive(Clone, Default)]
 struct BCaster {
-    pub store: Store,
-    pub gossips: Gossips,
+    store: HashSet<i64>,
+    gossips: HashMap<String, HashSet<i64>>,
+    neighbors: HashSet<String>,
+}
+
+const NUM_NEIGHBORS: i32 = 5;
+
+impl BCaster {
+    fn topology(&mut self, nodes: &[String], id: &str) {
+        let mut nodes = nodes.to_vec();
+        let len = nodes.len();
+        nodes.sort_unstable();
+        let idx = nodes
+            .iter()
+            .enumerate()
+            .find(|n| n.1.as_str() == id)
+            .unwrap()
+            .0;
+        for i in 1..=NUM_NEIGHBORS {
+            let ni = idx as i32 - i;
+            let left = if ni < 0 {
+                let ni = -ni;
+                let ni = ni as usize % len;
+                len - ni
+            } else {
+                ni as usize
+            };
+
+            let right = (idx + i as usize) % len;
+            self.neighbors.insert(nodes[left].clone());
+            self.neighbors.insert(nodes[right].clone());
+        }
+    }
+
+    fn gossip(&self, runner: &Runner) {
+        let mut rng = rand::thread_rng();
+        let rng = &mut rng;
+        for node in self.neighbors.iter() {
+            let mut goss = if let Some(neighbor) = self.gossips.get(node) {
+                self.store.difference(neighbor).cloned().collect()
+            } else {
+                self.store.clone()
+            };
+            for v in self.store.iter().filter(|_| rng.gen_bool(0.11)) {
+                goss.insert(*v);
+            }
+            if !goss.is_empty() {
+                let goss: Vec<_> = goss.into_iter().collect();
+                let payload: Payload = [("goss".to_string(), goss.into())].into_iter().collect();
+                let body = Body::from_type("gossip").with_payload(payload);
+                runner.send(node, body);
+            }
+        }
+    }
 }
 
 impl Node for BCaster {
     fn handle(&mut self, runner: &Runner, req: &Message) {
         let typ = req.body.typ.as_str();
         let frm = req.src.as_str();
-        let mid = req.body.msg_id;
         let nid = runner.node_id();
         let nid = nid.as_str();
-        let key = format!("{frm}-{mid}");
-        let key = key.as_str();
-
-        {
-            for (_, gossip) in self.gossips.iter() {
-                runner.send(gossip.clone());
-            }
-        }
 
         match typ {
-            "gossip_ok" => {
-                let id = req.body.in_reply_to;
-                self.gossips.remove(&id);
+            "do_gossip" => {
+                self.gossip(runner);
             }
             "broadcast" => {
                 let val = req.body.payload.get("message").and_then(|v| v.as_i64());
                 if let Some(val) = val {
-                    {
-                        // there's only one thread, safe to unwrap
-                        self.store.entry(key.to_owned()).or_insert(val);
-                    }
-
-                    let extra: Payload = [
-                        ("key".to_string(), key.into()),
-                        ("val".to_string(), val.into()),
-                    ]
-                    .into_iter()
-                    .collect();
-                    let gossip = Body::from_type("gossip").with_payload(extra);
-                    for node in runner.nodes().iter().filter(|n| n.as_str() != nid) {
-                        let id = runner.next_msg_id();
-                        let gossip = gossip.clone().with_msg_id(id);
-                        let msg = Message {
-                            body: gossip,
-                            src: nid.to_string(),
-                            dest: node.to_string(),
-                        };
-                        self.gossips.insert(id, msg.clone());
-
-                        runner.send(msg);
-                    }
+                    self.store.insert(val);
                     let body = Body::from_type("broadcast_ok");
                     runner.reply(req, body);
                 }
             }
             "read" => {
-                let vals = self.store.values().cloned().collect::<Vec<_>>();
-
+                let vals = self.store.iter().copied().collect::<Vec<_>>();
                 let payload: Payload = [("messages".to_string(), vals.into())]
                     .into_iter()
                     .collect();
@@ -86,17 +134,29 @@ impl Node for BCaster {
                 runner.reply(req, body);
             }
             "topology" => {
+                self.topology(runner.nodes(), nid);
                 let body = Body::from_type("topology_ok");
                 runner.reply(req, body);
             }
             "gossip" => {
-                let key = req.body.payload.get("key").unwrap().as_str().unwrap();
-                let val = req.body.payload.get("val").unwrap().as_i64().unwrap();
+                let goss = req
+                    .body
+                    .payload
+                    .get("goss")
+                    .unwrap()
+                    .as_array()
+                    .unwrap()
+                    .iter()
+                    .map(|v| v.as_i64().unwrap())
+                    .collect::<HashSet<_>>();
 
-                self.store.entry(key.to_string()).or_insert(val);
-                let body = Body::from_type("gossip_ok");
-                runner.reply(req, body);
+                self.store.extend(goss.clone());
+                self.gossips
+                    .entry(frm.to_string())
+                    .or_default()
+                    .extend(goss);
             }
+
             _ => {
                 eprintln!("unknown type: {req:?}");
             }
diff --git a/gg-echo/src/main.rs b/gg-echo/src/main.rs
index 36b6144..29b1124 100644
--- a/gg-echo/src/main.rs
+++ b/gg-echo/src/main.rs
@@ -1,4 +1,8 @@
-use std::{rc::Rc, sync::Mutex};
+use std::{
+    io::BufRead,
+    sync::{mpsc::channel, Arc, Mutex},
+    thread,
+};
 
 use nebkor_maelstrom::{Body, Message, Node, Runner};
 
@@ -7,24 +11,34 @@ struct Echo;
 impl Node for Echo {
     fn handle(&mut self, runner: &Runner, msg: &Message) {
         let typ = &msg.body.typ;
-        match typ.as_str() {
-            "echo" => {
-                let body = Body::from_type("echo_ok").with_payload(msg.body.payload.clone());
-                runner.reply(&msg, body);
-            }
-            _ => {}
+        if typ.as_str() == "echo" {
+            let body = Body::from_type("echo_ok").with_payload(msg.body.payload.clone());
+            runner.reply(msg, body);
         }
     }
 }
 
 fn main() {
-    let out = std::io::stdout().lock();
-    let input = std::io::stdin().lock();
+    let out = std::io::stdout();
+    let std_in = Arc::new(std::io::stdin());
+
+    let (tx, rx) = channel();
+
+    let i = thread::spawn(move || {
+        let g = std_in.lock();
+        for line in g.lines().map_while(Result::ok) {
+            if let Ok(msg) = serde_json::from_str::<Message>(&line) {
+                tx.send(msg).unwrap();
+            }
+        }
+    });
 
     let node = Echo;
-    let node = Rc::new(Mutex::new(node));
 
-    let runner = Runner::new(out, node);
+    let node = Arc::new(Mutex::new(node));
 
-    runner.run(input);
+    let runner = Runner::new(node, out);
+
+    runner.run(rx);
+    i.join().unwrap();
 }
diff --git a/gg-uid/src/main.rs b/gg-uid/src/main.rs
index 2a6168a..72800cb 100644
--- a/gg-uid/src/main.rs
+++ b/gg-uid/src/main.rs
@@ -1,17 +1,33 @@
-use std::{rc::Rc, sync::Mutex};
+use std::{
+    io::BufRead,
+    sync::{mpsc::channel, Arc, Mutex},
+    thread,
+};
 
 use nebkor_maelstrom::{protocol::Payload, Body, Message, Node, Runner};
 
 fn main() {
-    let out = std::io::stdout().lock();
-    let input = std::io::stdin().lock();
+    let out = std::io::stdout();
+    let std_in = Arc::new(std::io::stdin());
+
+    let (tx, rx) = channel();
+
+    let i = thread::spawn(move || {
+        let g = std_in.lock();
+        for line in g.lines().map_while(Result::ok) {
+            if let Ok(msg) = serde_json::from_str::<Message>(&line) {
+                tx.send(msg).unwrap();
+            }
+        }
+    });
 
     let node = GenUid;
-    let node = Rc::new(Mutex::new(node));
+    let node = Arc::new(Mutex::new(node));
 
-    let runner = Runner::new(out, node);
+    let runner = Runner::new(node, out);
 
-    runner.run(input);
+    runner.run(rx);
+    i.join().unwrap();
 }
 
 #[derive(Clone, Default)]
diff --git a/nebkor-maelstrom/src/lib.rs b/nebkor-maelstrom/src/lib.rs
index cb38e55..f6c929a 100644
--- a/nebkor-maelstrom/src/lib.rs
+++ b/nebkor-maelstrom/src/lib.rs
@@ -1,57 +1,53 @@
 use std::{
-    cell::OnceCell,
-    io::{BufRead, StdinLock, StdoutLock, Write},
-    rc::Rc,
+    io::{Stdout, Write},
     sync::{
-        atomic::{AtomicU64, Ordering},
-        Mutex,
+        atomic::{AtomicU64, AtomicUsize, Ordering},
+        Arc, Mutex, OnceLock,
     },
 };
 
 pub mod protocol;
 pub use protocol::{Body, Message};
 
-pub type DynNode = Rc<Mutex<dyn Node>>;
+pub type DynNode = Arc<Mutex<dyn Node>>;
 
 pub trait Node {
     fn handle(&mut self, runner: &Runner, msg: &Message);
 }
 
-pub struct Runner<'io> {
+pub struct Runner {
     msg_id: AtomicU64,
     node: DynNode,
-    node_id: OnceCell<String>,
-    nodes: OnceCell<Vec<String>>,
-    output: Mutex<StdoutLock<'io>>,
-    steps: AtomicU64,
+    node_id: OnceLock<String>,
+    nodes: OnceLock<Vec<String>>,
+    steps: AtomicUsize,
+    output: Arc<Mutex<Stdout>>,
 }
 
-impl<'io> Runner<'io> {
-    pub fn new(output: StdoutLock<'io>, node: DynNode) -> Self {
+impl Runner {
+    pub fn new(node: DynNode, output: Stdout) -> Self {
         Runner {
-            output: Mutex::new(output),
             node,
             msg_id: AtomicU64::new(1),
-            nodes: OnceCell::new(),
-            node_id: OnceCell::new(),
-            steps: AtomicU64::new(0),
+            nodes: OnceLock::new(),
+            node_id: OnceLock::new(),
+            steps: AtomicUsize::new(0),
+            output: Arc::new(Mutex::new(output)),
         }
     }
 
-    pub fn run(&self, input: StdinLock) {
-        for line in input.lines().map_while(Result::ok) {
-            if let Ok(msg) = serde_json::from_str::<Message>(&line) {
-                let typ = &msg.body.typ;
-                if let "init" = typ.as_str() {
-                    self.init(&msg);
-                    let body = Body::from_type("init_ok");
-                    self.reply(&msg, body);
-                } else {
-                    let mut n = self.node.lock().unwrap();
-                    n.handle(self, &msg);
-                }
-            }
+    pub fn run(&self, input: std::sync::mpsc::Receiver<Message>) {
+        for msg in input.iter() {
             self.steps.fetch_add(1, Ordering::SeqCst);
+            let typ = &msg.body.typ;
+            if let "init" = typ.as_str() {
+                self.init(&msg);
+                let body = Body::from_type("init_ok");
+                self.reply(&msg, body);
+            } else {
+                let mut n = self.node.lock().unwrap();
+                n.handle(self, &msg);
+            }
         }
     }
 
@@ -63,10 +59,18 @@ impl<'io> Runner<'io> {
         self.msg_id.fetch_add(1, Ordering::SeqCst)
     }
 
+    pub fn cur_msg_id(&self) -> u64 {
+        self.msg_id.load(Ordering::SeqCst)
+    }
+
     pub fn nodes(&self) -> &[String] {
         self.nodes.get().unwrap()
     }
 
+    pub fn steps(&self) -> usize {
+        self.steps.load(Ordering::SeqCst)
+    }
+
     pub fn init(&self, msg: &Message) {
         let node_id = msg
             .body
@@ -94,20 +98,22 @@ impl<'io> Runner<'io> {
 
     pub fn reply(&self, req: &Message, body: Body) {
         let mut body = body;
-        let src = self.node_id.get().unwrap().to_owned();
         let dest = req.src.clone();
         let in_reply_to = req.body.msg_id;
         body.in_reply_to = in_reply_to;
-        let msg = Message { src, dest, body };
-        self.send(msg);
+        self.send(&dest, body);
     }
 
-    pub fn send(&self, msg: Message) {
-        let mut msg = msg;
-        if msg.body.msg_id == 0 {
-            let mid = self.next_msg_id();
-            msg.body.msg_id = mid;
+    pub fn send(&self, dest: &str, body: Body) {
+        let mut body = body;
+        if body.msg_id == 0 {
+            body.msg_id = self.next_msg_id();
         }
+        let msg = Message {
+            src: self.node_id().to_string(),
+            dest: dest.to_string(),
+            body,
+        };
         let msg = serde_json::to_string(&msg).unwrap();
         self.writeln(&msg);
     }