diff --git a/pymongo/pool.py b/pymongo/pool.py
index 8bd6602cc..972a8c1db 100644
--- a/pymongo/pool.py
+++ b/pymongo/pool.py
@@ -487,6 +487,7 @@ class SocketInfo(object):
         self.enabled_for_cmap = pool.enabled_for_cmap
         self.compression_settings = pool.opts.compression_settings
         self.compression_context = None
+        self.socket_checker = SocketChecker()
 
         # The pool's generation changes with each reset() so we can close
         # sockets created before the last reset.
@@ -752,6 +753,10 @@ class SocketInfo(object):
             self.listeners.publish_connection_closed(
                 self.address, self.id, reason)
 
+    def socket_closed(self):
+        """Return True if we know socket has been closed, False otherwise."""
+        return self.socket_checker.socket_closed(self.sock)
+
     def send_cluster_time(self, command, session, client):
         """Add cluster time for MongoDB >= 3.6."""
         if self.max_wire_version >= 6 and client:
@@ -976,7 +981,6 @@ class Pool:
 
         self._socket_semaphore = thread_util.create_semaphore(
             self.opts.max_pool_size, max_waiters)
-        self.socket_checker = SocketChecker()
         if self.enabled_for_cmap:
             self.opts.event_listeners.publish_pool_created(
                 self.address, self.opts.non_default_options)
@@ -1244,7 +1248,7 @@ class Pool:
         if (self._check_interval_seconds is not None and (
                 0 == self._check_interval_seconds or
                 idle_time_seconds > self._check_interval_seconds)):
-            if self.socket_checker.socket_closed(sock_info.sock):
+            if sock_info.socket_closed():
                 sock_info.close_socket(ConnectionClosedReason.ERROR)
                 return True
 
diff --git a/pymongo/socket_checker.py b/pymongo/socket_checker.py
index 9b21e69d2..93d6cb5a4 100644
--- a/pymongo/socket_checker.py
+++ b/pymongo/socket_checker.py
@@ -16,7 +16,6 @@
 
 import errno
 import select
-import threading
 
 _HAVE_POLL = hasattr(select, "poll")
 _SelectError = getattr(select, "error", OSError)
@@ -34,10 +33,8 @@ class SocketChecker(object):
 
     def __init__(self):
         if _HAVE_POLL:
-            self._lock = threading.Lock()
             self._poller = select.poll()
         else:
-            self._lock = None
             self._poller = None
 
     def select(self, sock, read=False, write=False, timeout=0):
@@ -50,14 +47,13 @@ class SocketChecker(object):
                         mask = mask | select.POLLIN | select.POLLPRI
                     if write:
                         mask = mask | select.POLLOUT
-                    with self._lock:
-                        self._poller.register(sock, mask)
-                        try:
-                            # poll() timeout is in milliseconds. select()
-                            # timeout is in seconds.
-                            res = self._poller.poll(timeout * 1000)
-                        finally:
-                            self._poller.unregister(sock)
+                    self._poller.register(sock, mask)
+                    try:
+                        # poll() timeout is in milliseconds. select()
+                        # timeout is in seconds.
+                        res = self._poller.poll(timeout * 1000)
+                    finally:
+                        self._poller.unregister(sock)
                 else:
                     rlist = [sock] if read else []
                     wlist = [sock] if write else []
diff --git a/test/test_pooling.py b/test/test_pooling.py
index bfe5abc11..8ed4068a6 100644
--- a/test/test_pooling.py
+++ b/test/test_pooling.py
@@ -236,8 +236,7 @@ class TestPooling(_TestPoolingBase):
             # Simulate a closed socket without telling the SocketInfo it's
             # closed.
             sock_info.sock.close()
-            self.assertTrue(
-                cx_pool.socket_checker.socket_closed(sock_info.sock))
+            self.assertTrue(sock_info.socket_closed())
 
         with cx_pool.get_socket({}) as new_sock_info:
             self.assertEqual(0, len(cx_pool.sockets))
@@ -257,25 +256,6 @@ class TestPooling(_TestPoolingBase):
         s.close()
         self.assertTrue(socket_checker.socket_closed(s))
 
-    def test_socket_closed_thread_safe(self):
-        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-        s.connect((client_context.host, client_context.port))
-        self.addCleanup(s.close)
-        socket_checker = SocketChecker()
-
-        def check_socket():
-            for _ in range(1000):
-                self.assertFalse(socket_checker.socket_closed(s))
-
-        threads = []
-        for i in range(3):
-            thread = threading.Thread(target=check_socket)
-            thread.start()
-            threads.append(thread)
-
-        for thread in threads:
-            thread.join()
-
     def test_return_socket_after_reset(self):
         pool = self.create_pool()
         with pool.get_socket({}) as sock: