diff --git a/rayoff/src/rayoff.rs b/rayoff/src/rayoff.rs
index 7ca3773fa46084..b27a68b8b70cfc 100644
--- a/rayoff/src/rayoff.rs
+++ b/rayoff/src/rayoff.rs
@@ -2,32 +2,30 @@ extern crate sys_info;
 
 use job::Job;
 use std::sync::mpsc::{channel, Receiver, Sender};
-use std::sync::Arc;
-use std::thread::{spawn, JoinHandle};
+use std::sync::{Mutex, Arc};
+use std::thread::{spawn};
 
+#[derive(Debug)]
 pub struct Pool {
-    senders: Vec<Sender<Arc<Job>>>,
-    threads: Vec<JoinHandle<()>>,
+    senders: Mutex<Vec<Sender<Arc<Job>>>>,
 }
 
 impl Default for Pool {
     fn default() -> Self {
         let num_threads = sys_info::cpu_num().unwrap_or(16) - 1;
-        let mut pool = Self {
-            senders: vec![],
-            threads: vec![],
-        };
+        let mut senders = vec![];
         (0..num_threads).for_each(|_| {
             let (sender, recvr): (Sender<Arc<Job>>, Receiver<Arc<Job>>) = channel();
-            let t = spawn(move || {
+            let _ = spawn(move || {
                 for job in recvr.iter() {
                     job.execute()
                 }
             });
-            pool.senders.push(sender);
-            pool.threads.push(t);
+            senders.push(sender);
         });
-        pool
+        Self {
+            senders: Mutex::new(senders),
+        }
     }
 }
 
@@ -39,11 +37,9 @@ impl Pool {
         // Job must be destroyed in the frame that its created
         let job = unsafe { Job::new(elems, func) };
         let job = Arc::new(job);
-        for s in &self.senders {
-            s.send(job.clone()).expect("send should never fail");
-        }
+        let len = self.notify_all(job.clone());
         job.execute();
-        job.wait(self.senders.len() + 1);
+        job.wait(len + 1);
     }
     pub fn map<F, A, B>(&self, inputs: &[A], func: F) -> Vec<B>
     where
@@ -58,6 +54,14 @@ impl Pool {
         });
         outs
     }
+    fn notify_all(&self, job: Arc<Job>) -> usize {
+        let senders = self.senders.lock().unwrap();
+        let len = senders.len();
+        for s in senders.iter() {
+            s.send(job.clone()).expect("send should never fail");
+        }
+        len
+    }
 }
 
 #[cfg(test)]
diff --git a/runtime/src/accounts.rs b/runtime/src/accounts.rs
index 1bc0efbbc542c4..0cdf6a182e302e 100644
--- a/runtime/src/accounts.rs
+++ b/runtime/src/accounts.rs
@@ -287,8 +287,8 @@ impl Accounts {
     /// returns only the latest/current version of B for this slot
     fn scan_slot<F, B>(&self, slot: Slot, func: F) -> Vec<B>
     where
-        F: Fn(&StoredAccount) -> Option<B> + 'static,
-        B: Clone + Default,
+        F: Fn(&StoredAccount) -> Option<B> + Send + Sync,
+        B: Clone + Default + Send,
     {
         let accumulator: Vec<Vec<(Pubkey, u64, B)>> = self.accounts_db.scan_account_storage(
             slot,
diff --git a/runtime/src/accounts_db.rs b/runtime/src/accounts_db.rs
index 740302481b3fff..cd8b489cd062ec 100644
--- a/runtime/src/accounts_db.rs
+++ b/runtime/src/accounts_db.rs
@@ -611,8 +611,8 @@ impl AccountsDB {
     // PERF: Sequentially read each storage entry in parallel
     pub fn scan_account_storage<F, B>(&self, slot_id: Slot, scan_func: F) -> Vec<B>
     where
-        F: Fn(&StoredAccount, AppendVecId, &mut B) -> () + 'static,
-        B: Default + Clone,
+        F: Fn(&StoredAccount, AppendVecId, &mut B) -> () + Send + Sync,
+        B: Default + Clone + Send,
     {
         let storage_maps: Vec<Arc<AccountStorageEntry>> = self
             .storage