9 files changed, 8 insertions, 83 deletions
diff --git a/cli/diagnostics.rs b/cli/diagnostics.rs
index e131d21af..615a13225 100644
--- a/cli/diagnostics.rs
+++ b/cli/diagnostics.rs
@@ -52,7 +52,6 @@ const UNSTABLE_DENO_PROPS: &[&str] = &[
   "setRaw",
   "shutdown",
   "Signal",
-  "sleepSync",
   "startTls",
   "systemMemoryInfo",
   "umask",
diff --git a/cli/dts/lib.deno.unstable.d.ts b/cli/dts/lib.deno.unstable.d.ts
index 12f53b784..7ebd80422 100644
--- a/cli/dts/lib.deno.unstable.d.ts
+++ b/cli/dts/lib.deno.unstable.d.ts
@@ -753,17 +753,6 @@ declare namespace Deno {
 
   /** **UNSTABLE**: new API, yet to be vetted.
    *
-   * SleepSync puts the main thread to sleep synchronously for a given amount of
-   * time in milliseconds.
-   *
-   * ```ts
-   * Deno.sleepSync(10);
-   * ```
-   */
-  export function sleepSync(millis: number): void;
-
-  /** **UNSTABLE**: new API, yet to be vetted.
-   *
    * A generic transport listener for message-oriented protocols. */
   export interface DatagramConn extends AsyncIterable<[Uint8Array, Addr]> {
     /** **UNSTABLE**: new API, yet to be vetted.
diff --git a/cli/tests/testdata/worker_drop_handle_race_terminate.js b/cli/tests/testdata/worker_drop_handle_race_terminate.js
index fc9a4e6b2..93c324fdf 100644
--- a/cli/tests/testdata/worker_drop_handle_race_terminate.js
+++ b/cli/tests/testdata/worker_drop_handle_race_terminate.js
@@ -13,10 +13,10 @@ const WORKER2 = getCodeBlobUrl(`
   console.log("Worker 2");
   self.postMessage(undefined);
 
-  // We sleep for slightly under 2 seconds in order to make sure that worker 1
-  // has closed, and that this worker's thread finishes normally rather than
-  // being killed (which happens 2 seconds after calling terminate).
-  Deno.sleepSync(1800);
+  // We sleep synchronously for slightly under 2 seconds in order to make sure
+  // that worker 1 has closed, and that this worker's thread finishes normally
+  // rather than being killed (which happens 2 seconds after calling terminate).
+  Atomics.wait(new Int32Array(new SharedArrayBuffer(4)), 0, 0, 1800);
   console.log("Finished sleeping in worker 2");
 `);
 
diff --git a/cli/tests/unit/flock_test.ts b/cli/tests/unit/flock_test.ts
index 3c73d0481..fbc061593 100644
--- a/cli/tests/unit/flock_test.ts
+++ b/cli/tests/unit/flock_test.ts
@@ -136,7 +136,7 @@ function runFlockTestProcess(opts: { exclusive: boolean; sync: boolean }) {
     // the lock so that the enter time of the next process doesn't
     // occur at the same time as this exit time
     const exitTime = new Date().getTime();
-    Deno.sleepSync(100);
+    await new Promise(resolve => setTimeout(resolve, 100));
 
     // release the lock
     ${opts.sync ? "Deno.funlockSync(rid);" : "await Deno.funlock(rid);"}
diff --git a/cli/tests/unit/timers_test.ts b/cli/tests/unit/timers_test.ts
index ef7dc9eef..e6901a42c 100644
--- a/cli/tests/unit/timers_test.ts
+++ b/cli/tests/unit/timers_test.ts
@@ -215,7 +215,7 @@ Deno.test(async function callbackTakesLongerThanInterval() {
   const interval = setInterval(() => {
     if (timeEndOfFirstCallback === undefined) {
       // First callback
-      Deno.sleepSync(300);
+      Atomics.wait(new Int32Array(new SharedArrayBuffer(4)), 0, 0, 300);
       timeEndOfFirstCallback = Date.now();
     } else {
       // Second callback
@@ -237,7 +237,7 @@ Deno.test(async function clearTimeoutAfterNextTimerIsDue1() {
   }, 300);
 
   const interval = setInterval(() => {
-    Deno.sleepSync(400);
+    Atomics.wait(new Int32Array(new SharedArrayBuffer(4)), 0, 0, 400);
     // Both the interval and the timeout's due times are now in the past.
     clearInterval(interval);
   }, 100);
@@ -255,7 +255,7 @@ Deno.test(async function clearTimeoutAfterNextTimerIsDue2() {
     promise.resolve();
   }, 200);
 
-  Deno.sleepSync(300);
+  Atomics.wait(new Int32Array(new SharedArrayBuffer(4)), 0, 0, 300);
   // Both of the timeouts' due times are now in the past.
   clearTimeout(timeout1);
 
@@ -531,52 +531,6 @@ Deno.test(async function timerIgnoresDateOverride() {
   assertEquals(hasThrown, 1);
 });
 
-Deno.test({ permissions: { hrtime: true } }, function sleepSync() {
-  const start = performance.now();
-  Deno.sleepSync(10);
-  const after = performance.now();
-  assert(after - start >= 10);
-});
-
-Deno.test(
-  { permissions: { hrtime: true } },
-  async function sleepSyncShorterPromise() {
-    const perf = performance;
-    const short = 5;
-    const long = 10;
-
-    const start = perf.now();
-    const p = delay(short).then(() => {
-      const after = perf.now();
-      // pending promises should resolve after the main thread comes out of sleep
-      assert(after - start >= long);
-    });
-    Deno.sleepSync(long);
-
-    await p;
-  },
-);
-
-Deno.test(
-  { permissions: { hrtime: true } },
-  async function sleepSyncLongerPromise() {
-    const perf = performance;
-    const short = 5;
-    const long = 10;
-
-    const start = perf.now();
-    const p = delay(long).then(() => {
-      const after = perf.now();
-      // sleeping for less than the duration of a promise should have no impact
-      // on the resolution of that promise
-      assert(after - start >= long);
-    });
-    Deno.sleepSync(short);
-
-    await p;
-  },
-);
-
 Deno.test({
   name: "unrefTimer",
   permissions: { run: true, read: true },
diff --git a/ext/web/02_timers.js b/ext/web/02_timers.js
index edad89ace..a4ce33a18 100644
--- a/ext/web/02_timers.js
+++ b/ext/web/02_timers.js
@@ -28,10 +28,6 @@
     return core.opSync("op_now");
   }
 
-  function sleepSync(millis = 0) {
-    return core.opSync("op_sleep_sync", millis);
-  }
-
   // ---------------------------------------------------------------------------
 
   /**
@@ -372,7 +368,6 @@
     clearInterval,
     handleTimerMacrotask,
     opNow,
-    sleepSync,
     refTimer,
     unrefTimer,
   };
diff --git a/ext/web/lib.rs b/ext/web/lib.rs
index ae5cf2d80..b21ea3812 100644
--- a/ext/web/lib.rs
+++ b/ext/web/lib.rs
@@ -52,7 +52,6 @@ pub use crate::message_port::MessagePort;
 
 use crate::timers::op_now;
 use crate::timers::op_sleep;
-use crate::timers::op_sleep_sync;
 use crate::timers::op_timer_handle;
 use crate::timers::StartTime;
 pub use crate::timers::TimersPermission;
@@ -111,7 +110,6 @@ pub fn init<P: TimersPermission + 'static>(
       op_timer_handle::decl(),
       op_cancel_handle::decl(),
       op_sleep::decl(),
-      op_sleep_sync::decl::<P>(),
     ])
     .state(move |state| {
       state.put(blob_store.clone());
diff --git a/ext/web/timers.rs b/ext/web/timers.rs
index eee770719..f57baa559 100644
--- a/ext/web/timers.rs
+++ b/ext/web/timers.rs
@@ -82,12 +82,3 @@ pub async fn op_sleep(
     .await?;
   Ok(())
 }
-
-#[op]
-pub fn op_sleep_sync<TP>(state: &mut OpState, millis: u64)
-where
-  TP: TimersPermission + 'static,
-{
-  state.borrow::<TP>().check_unstable(state, "Deno.sleepSync");
-  std::thread::sleep(Duration::from_millis(millis));
-}
diff --git a/runtime/js/90_deno_ns.js b/runtime/js/90_deno_ns.js
index 24a31bc31..ea5303149 100644
--- a/runtime/js/90_deno_ns.js
+++ b/runtime/js/90_deno_ns.js
@@ -126,7 +126,6 @@
     networkInterfaces: __bootstrap.os.networkInterfaces,
     getGid: __bootstrap.os.getGid,
     getUid: __bootstrap.os.getUid,
-    sleepSync: __bootstrap.timers.sleepSync,
     listen: __bootstrap.netUnstable.listen,
     connect: __bootstrap.netUnstable.connect,
     listenDatagram: __bootstrap.netUnstable.listenDatagram,