add some queue for nodes operations

ydb/tools/ydbd_slice/__init__.py

@@ -315,7 +315,7 @@ def deduce_nodes_from_args(args, walle_provider, ssh_user):
         sys.exit("unable to deduce hosts")
 
     logger.info("use nodes '%s'", result)
-    return nodes.Nodes(result, args.dry_run, ssh_user=ssh_user)
+    return nodes.Nodes(result, args.dry_run, ssh_user=ssh_user, queue_size=args.cmd_queue_size)
 
 
 def ya_build(arcadia_root, artifact, opts, dry_run):
@@ -1187,6 +1187,13 @@ def main(walle_provider=None):
             default="ver-01gswscgce37hdbqyssjm3nd7x",
             help=''
         )
+        parser.add_argument(
+            "--cmd-queue-size",
+            metavar="SIZE",
+            type=int,
+            default=0,
+            help='the size of the command queue (for ssh commands), which limits their parallel execution on remote nodes'
+        )
 
         modes = parser.add_subparsers()
         walle_provider = walle_provider or NopHostsInformationProvider()

ydb/tools/ydbd_slice/nodes.py

@@ -2,20 +2,23 @@
 import sys
 import logging
 import subprocess
+import queue
 
 
 logger = logging.getLogger(__name__)
 
 
 class Nodes(object):
-    def __init__(self, nodes, dry_run=False, ssh_user=None):
+    def __init__(self, nodes, dry_run=False, ssh_user=None, queue_size=0):
         assert isinstance(nodes, list)
         assert len(nodes) > 0
         assert isinstance(nodes[0], str)
         self._nodes = nodes
         self._dry_run = bool(dry_run)
         self._ssh_user = ssh_user
         self._logger = logger.getChild(self.__class__.__name__)
+        self._queue = queue.Queue(queue_size)
+        self._qsize = queue_size
 
     @property
     def nodes_list(self):
@@ -83,7 +86,23 @@ def execute_async_ret(self, cmd, check_retcode=True, nodes=None, results=None):
 
             actual_cmd = self._get_ssh_command_prefix() + [host, cmd]
             process = subprocess.Popen(actual_cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+
+            if self._qsize > 0:
+                self._queue.put((actual_cmd, process, host))
+                if not self._queue.full():
+                    continue
+                if not self._queue.empty():
+                    actual_cmd, process, host = self._queue.get()
+                    process.wait()
+
             running_jobs.append((actual_cmd, process, host))
+
+        if self._qsize > 0:
+            while not self._queue.empty():
+                actual_cmd, process, host = self._queue.get()
+                process.wait()
+                running_jobs.append((actual_cmd, process, host))
+
         return running_jobs
 
     def execute_async(self, cmd, check_retcode=True, nodes=None, results=None):