diff --git a/python/ray/memory_monitor.py b/python/ray/memory_monitor.py
index 40980a09e..f6d6f352c 100644
--- a/python/ray/memory_monitor.py
+++ b/python/ray/memory_monitor.py
@@ -102,33 +102,38 @@ class MemoryMonitor:
         self.heap_limit = limit_bytes
         self.worker_name = worker_name
 
+    def get_memory_usage(self):
+        psutil_mem = psutil.virtual_memory()
+        total_gb = psutil_mem.total / (1024**3)
+        used_gb = total_gb - psutil_mem.available / (1024**3)
+
+        # Linux, BSD has cached memory, which should
+        # also be considered as unused memory
+        if hasattr(psutil_mem, "cached"):
+            used_gb -= psutil_mem.cached / (1024**3)
+
+        if self.cgroup_memory_limit_gb < total_gb:
+            total_gb = self.cgroup_memory_limit_gb
+            with open("/sys/fs/cgroup/memory/memory.usage_in_bytes",
+                      "rb") as f:
+                used_gb = int(f.read()) / (1024**3)
+            # Exclude the page cache
+            with open("/sys/fs/cgroup/memory/memory.stat", "r") as f:
+                for line in f.readlines():
+                    if line.split(" ")[0] == "cache":
+                        used_gb = \
+                            used_gb - int(line.split(" ")[1]) / (1024**3)
+            assert used_gb >= 0
+        return used_gb, total_gb
+
     def raise_if_low_memory(self):
         if time.time() - self.last_checked > self.check_interval:
             if "RAY_DEBUG_DISABLE_MEMORY_MONITOR" in os.environ:
                 return  # escape hatch, not intended for user use
 
             self.last_checked = time.time()
-            psutil_mem = psutil.virtual_memory()
-            total_gb = psutil_mem.total / (1024**3)
-            used_gb = total_gb - psutil_mem.available / (1024**3)
+            used_gb, total_gb = self.get_memory_usage()
 
-            # Linux, BSD has cached memory, which should
-            # also be considered as unused memory
-            if hasattr(psutil_mem, "cached"):
-                used_gb -= psutil_mem.cached / (1024**3)
-
-            if self.cgroup_memory_limit_gb < total_gb:
-                total_gb = self.cgroup_memory_limit_gb
-                with open("/sys/fs/cgroup/memory/memory.usage_in_bytes",
-                          "rb") as f:
-                    used_gb = int(f.read()) / (1024**3)
-                # Exclude the page cache
-                with open("/sys/fs/cgroup/memory/memory.stat", "r") as f:
-                    for line in f.readlines():
-                        if line.split(" ")[0] == "cache":
-                            used_gb = \
-                                used_gb - int(line.split(" ")[1]) / (1024**3)
-                assert used_gb >= 0
             if used_gb > total_gb * self.error_threshold:
                 raise RayOutOfMemoryError(
                     RayOutOfMemoryError.get_message(used_gb, total_gb,