[autoscaler] Fix ssh control path length issue (#5476)

python/ray/autoscaler/updater.py

@@ -6,6 +6,7 @@ try:  # py3
     from shlex import quote
 except ImportError:  # py2
     from pipes import quote
+import hashlib
 import logging
 import os
 import subprocess
@@ -23,7 +24,7 @@ logger = logging.getLogger(__name__)
 # How long to wait for a node to start, in seconds
 NODE_START_WAIT_S = 300
 SSH_CHECK_INTERVAL = 5
-CONTROL_PATH_MAX_LENGTH = 70
+HASH_MAX_LENGTH = 10
 
 
 def get_default_ssh_options(private_key, connect_timeout, ssh_control_path):
@@ -57,8 +58,11 @@ class NodeUpdater(object):
                  exit_on_update_fail=False,
                  use_internal_ip=False):
 
-        ssh_control_path = "/tmp/{}_ray_ssh_sockets/{}".format(
-            getuser(), cluster_name)[:CONTROL_PATH_MAX_LENGTH]
+        ssh_control_hash = hashlib.md5(cluster_name.encode()).hexdigest()
+        ssh_user_hash = hashlib.md5(getuser().encode()).hexdigest()
+        ssh_control_path = "/tmp/ray_ssh_{}/{}".format(
+            ssh_user_hash[:HASH_MAX_LENGTH],
+            ssh_control_hash[:HASH_MAX_LENGTH])
 
         self.daemon = True
         self.process_runner = process_runner