convert std::sync::mpsc to crossbeam_channel (#22264)

core/tests/ledger_cleanup.rs

@@ -4,6 +4,7 @@
 #[cfg(test)]
 mod tests {
     use {
+        crossbeam_channel::unbounded,
         log::*,
         solana_core::ledger_cleanup_service::LedgerCleanupService,
         solana_ledger::{
@@ -17,7 +18,6 @@ mod tests {
             str::FromStr,
             sync::{
                 atomic::{AtomicBool, AtomicU64, Ordering},
-                mpsc::channel,
                 Arc, Mutex, RwLock,
             },
             thread::{self, Builder, JoinHandle},
@@ -309,7 +309,7 @@ mod tests {
         let num_batches = benchmark_slots / batch_size_slots;
         let num_shreds_total = benchmark_slots * shreds_per_slot;
 
-        let (sender, receiver) = channel();
+        let (sender, receiver) = unbounded();
         let exit = Arc::new(AtomicBool::new(false));
 
         let cleaner = if cleanup_service {
@@ -587,7 +587,7 @@ mod tests {
         let u1 = blockstore.storage_size().unwrap() as f64;
 
         // send signal to cleanup slots
-        let (sender, receiver) = channel();
+        let (sender, receiver) = unbounded();
         sender.send(n).unwrap();
         let mut last_purge_slot = 0;
         let highest_compact_slot = Arc::new(AtomicU64::new(0));