prompt: You will be provided with a partial code base and an issue statement explaining a problem to resolve.
  <issue>
  [BUG]: colossalai run failed with unknown reason
  ### 🐛 Describe the bug
  
  Some users have reported that they encounter launch failure when using `colossalai run`, but there is no error message to tell exactly what went wrong. A sample output is given below.
  
  ```text
  Error: failed to run torchrun --nproc_per_node=4 --nnodes=1 --node_rank=0 --rdzv_backend=c10d --rdzv_endpoint=127.0.0.1:29500 --rdzv_id=colossalai-default-job train.py --config config.py -s on 127.0.0.1
  ```
  
  ### Environment
  
  _No response_
  
  </issue>
  <code>
  [start of colossalai/cli/launcher/multinode_runner.py]
  1 import fabric
  2 from .hostinfo import HostInfo, HostInfoList
  3 from multiprocessing import Pipe, Process
  4 from multiprocessing import connection as mp_connection
  5 import click
  6 
  7 
  8 def run_on_host(hostinfo: HostInfo, workdir: str, recv_conn: mp_connection.Connection,
  9                 send_conn: mp_connection.Connection, env: dict) -> None:
  10     """
  11     Use fabric connection to execute command on local or remote hosts.
  12 
  13     Args:
  14         hostinfo (HostInfo): host information
  15         workdir (str): the directory to execute the command
  16         recv_conn (multiprocessing.connection.Connection): receive messages from the master sender
  17         send_conn (multiprocessing.connection.Connection): send messages to the master receiver
  18         env (dict): a dictionary for environment variables
  19     """
  20 
  21     fab_conn = fabric.Connection(hostinfo.hostname, port=hostinfo.port)
  22     finish = False
  23     env_msg = ' '.join([f'{k}=\"{v}\"' for k, v in env.items()])
  24 
  25     # keep listening until exit
  26     while not finish:
  27         # receive cmd
  28         cmds = recv_conn.recv()
  29 
  30         if cmds == 'exit':
  31             # exit from the loop
  32             finish = True
  33             break
  34         else:
  35             # execute the commands
  36             try:
  37                 # cd to execute directory
  38                 with fab_conn.cd(workdir):
  39                     # propagate the runtime environment
  40                     with fab_conn.prefix(f"export {env_msg}"):
  41                         if hostinfo.is_local_host:
  42                             # execute on the local machine
  43                             fab_conn.local(cmds, hide=False)
  44                         else:
  45                             # execute on the remote machine
  46                             fab_conn.run(cmds, hide=False)
  47                     send_conn.send('success')
  48             except:
  49                 click.echo(f"Error: failed to run {cmds} on {hostinfo.hostname}")
  50                 send_conn.send('failure')
  51 
  52     # shutdown
  53     send_conn.send("finish")
  54     fab_conn.close()
  55 
  56 
  57 class MultiNodeRunner:
  58     """
  59     A runner to execute commands on an array of machines. This runner
  60     is inspired by Nezha (https://github.com/zhuzilin/NeZha).
  61     """
  62 
  63     def __init__(self):
  64         self.processes = {}
  65         self.master_send_conns = {}
  66         self.master_recv_conns = {}
  67 
  68     def connect(self, host_info_list: HostInfoList, workdir: str, env: dict) -> None:
  69         """
  70         Establish connections to a list of hosts
  71 
  72         Args:
  73             host_info_list (HostInfoList): a list of HostInfo objects
  74             workdir (str): the directory where command is executed
  75             env (dict): environment variables to propagate to hosts
  76         """
  77         for hostinfo in host_info_list:
  78             master_send_conn, worker_recv_conn = Pipe()
  79             master_recv_conn, worker_send_conn = Pipe()
  80             p = Process(target=run_on_host, args=(hostinfo, workdir, worker_recv_conn, worker_send_conn, env))
  81             p.start()
  82             self.processes[hostinfo.hostname] = p
  83             self.master_recv_conns[hostinfo.hostname] = master_recv_conn
  84             self.master_send_conns[hostinfo.hostname] = master_send_conn
  85 
  86     def send(self, hostinfo: HostInfo, cmd: str) -> None:
  87         """
  88         Send a command to a local/remote host.
  89 
  90         Args:
  91             hostinfo (HostInfo): host information
  92             cmd (str): the command to execute
  93         """
  94 
  95         assert hostinfo.hostname in self.master_send_conns, \
  96             f'{hostinfo} is not found in the current connections'
  97         conn = self.master_send_conns[hostinfo.hostname]
  98         conn.send(cmd)
  99 
  100     def stop_all(self) -> None:
  101         """
  102         Stop connections to all hosts.
  103         """
  104 
  105         for hostname, conn in self.master_send_conns.items():
  106             conn.send('exit')
  107 
  108     def recv_from_all(self) -> dict:
  109         """
  110         Receive messages from all hosts
  111 
  112         Returns:
  113             msg_from_node (dict): a dictionry which contains messages from each node
  114         """
  115 
  116         msg_from_node = dict()
  117         for hostname, conn in self.master_recv_conns.items():
  118             msg_from_node[hostname] = conn.recv()
  119         return msg_from_node
  120
  [end of colossalai/cli/launcher/multinode_runner.py]
  </code>
  
  I need you to solve this issue by generating a single patch file that I can apply directly to this repository using git apply. Please respond with a single patch file in the following format.
  <patch>
  diff --git a/file.py b/file.py
  --- a/file.py
  +++ b/file.py
  @@ -1,27 +1,35 @@
   def euclidean(a, b):
  -    while b:
  -        a, b = b, a % b
  -    return a
  +    if b == 0:
  +        return a
  +    return euclidean(b, a % b)
   
   
   def bresenham(x0, y0, x1, y1):
       points = []
       dx = abs(x1 - x0)
       dy = abs(y1 - y0)
  -    sx = 1 if x0 < x1 else -1
  -    sy = 1 if y0 < y1 else -1
  -    err = dx - dy
  +    x, y = x0, y0
  +    sx = -1 if x0 > x1 else 1
  +    sy = -1 if y0 > y1 else 1
   
  -    while True:
  -        points.append((x0, y0))
  -        if x0 == x1 and y0 == y1:
  -            break
  -        e2 = 2 * err
  -        if e2 > -dy:
  -            err -= dy
  -            x0 += sx
  -        if e2 < dx:
  -            err += dx
  -            y0 += sy
  +    if dx > dy:
  +        err = dx / 2.0
  +        while x != x1:
  +            points.append((x, y))
  +            err -= dy
  +            if err < 0:
  +                y += sy
  +                err += dx
  +            x += sx
  +    else:
  +        err = dy / 2.0
  +        while y != y1:
  +            points.append((x, y))
  +            err -= dx
  +            if err < 0:
  +                x += sx
  +                err += dy
  +            y += sy
  +
  +    points.append((x, y))
       return points
  
  </patch>
golden_diff: diff --git a/colossalai/cli/launcher/multinode_runner.py b/colossalai/cli/launcher/multinode_runner.py
  --- a/colossalai/cli/launcher/multinode_runner.py
  +++ b/colossalai/cli/launcher/multinode_runner.py
  @@ -1,8 +1,10 @@
  -import fabric
  -from .hostinfo import HostInfo, HostInfoList
   from multiprocessing import Pipe, Process
   from multiprocessing import connection as mp_connection
  +
   import click
  +import fabric
  +
  +from .hostinfo import HostInfo, HostInfoList
   
   
   def run_on_host(hostinfo: HostInfo, workdir: str, recv_conn: mp_connection.Connection,
  @@ -45,8 +47,10 @@
                               # execute on the remote machine
                               fab_conn.run(cmds, hide=False)
                       send_conn.send('success')
  -            except:
  -                click.echo(f"Error: failed to run {cmds} on {hostinfo.hostname}")
  +            except Exception as e:
  +                click.echo(
  +                    f"Error: failed to run {cmds} on {hostinfo.hostname}, is localhost: {hostinfo.is_local_host}, exception: {e}"
  +                )
                   send_conn.send('failure')
   
       # shutdown
  
verification_info: {"golden_diff": "diff --git a/colossalai/cli/launcher/multinode_runner.py b/colossalai/cli/launcher/multinode_runner.py\n--- a/colossalai/cli/launcher/multinode_runner.py\n+++ b/colossalai/cli/launcher/multinode_runner.py\n@@ -1,8 +1,10 @@\n-import fabric\n-from .hostinfo import HostInfo, HostInfoList\n from multiprocessing import Pipe, Process\n from multiprocessing import connection as mp_connection\n+\n import click\n+import fabric\n+\n+from .hostinfo import HostInfo, HostInfoList\n \n \n def run_on_host(hostinfo: HostInfo, workdir: str, recv_conn: mp_connection.Connection,\n@@ -45,8 +47,10 @@\n                             # execute on the remote machine\n                             fab_conn.run(cmds, hide=False)\n                     send_conn.send('success')\n-            except:\n-                click.echo(f\"Error: failed to run {cmds} on {hostinfo.hostname}\")\n+            except Exception as e:\n+                click.echo(\n+                    f\"Error: failed to run {cmds} on {hostinfo.hostname}, is localhost: {hostinfo.is_local_host}, exception: {e}\"\n+                )\n                 send_conn.send('failure')\n \n     # shutdown\n", "issue": "[BUG]: colossalai run failed with unknown reason\n### \ud83d\udc1b Describe the bug\n\nSome users have reported that they encounter launch failure when using `colossalai run`, but there is no error message to tell exactly what went wrong. A sample output is given below.\r\n\r\n```text\r\nError: failed to run torchrun --nproc_per_node=4 --nnodes=1 --node_rank=0 --rdzv_backend=c10d --rdzv_endpoint=127.0.0.1:29500 --rdzv_id=colossalai-default-job train.py --config config.py -s on 127.0.0.1\r\n```\n\n### Environment\n\n_No response_\n", "before_files": [{"content": "import fabric\nfrom .hostinfo import HostInfo, HostInfoList\nfrom multiprocessing import Pipe, Process\nfrom multiprocessing import connection as mp_connection\nimport click\n\n\ndef run_on_host(hostinfo: HostInfo, workdir: str, recv_conn: mp_connection.Connection,\n                send_conn: mp_connection.Connection, env: dict) -> None:\n    \"\"\"\n    Use fabric connection to execute command on local or remote hosts.\n\n    Args:\n        hostinfo (HostInfo): host information\n        workdir (str): the directory to execute the command\n        recv_conn (multiprocessing.connection.Connection): receive messages from the master sender\n        send_conn (multiprocessing.connection.Connection): send messages to the master receiver\n        env (dict): a dictionary for environment variables\n    \"\"\"\n\n    fab_conn = fabric.Connection(hostinfo.hostname, port=hostinfo.port)\n    finish = False\n    env_msg = ' '.join([f'{k}=\\\"{v}\\\"' for k, v in env.items()])\n\n    # keep listening until exit\n    while not finish:\n        # receive cmd\n        cmds = recv_conn.recv()\n\n        if cmds == 'exit':\n            # exit from the loop\n            finish = True\n            break\n        else:\n            # execute the commands\n            try:\n                # cd to execute directory\n                with fab_conn.cd(workdir):\n                    # propagate the runtime environment\n                    with fab_conn.prefix(f\"export {env_msg}\"):\n                        if hostinfo.is_local_host:\n                            # execute on the local machine\n                            fab_conn.local(cmds, hide=False)\n                        else:\n                            # execute on the remote machine\n                            fab_conn.run(cmds, hide=False)\n                    send_conn.send('success')\n            except:\n                click.echo(f\"Error: failed to run {cmds} on {hostinfo.hostname}\")\n                send_conn.send('failure')\n\n    # shutdown\n    send_conn.send(\"finish\")\n    fab_conn.close()\n\n\nclass MultiNodeRunner:\n    \"\"\"\n    A runner to execute commands on an array of machines. This runner\n    is inspired by Nezha (https://github.com/zhuzilin/NeZha).\n    \"\"\"\n\n    def __init__(self):\n        self.processes = {}\n        self.master_send_conns = {}\n        self.master_recv_conns = {}\n\n    def connect(self, host_info_list: HostInfoList, workdir: str, env: dict) -> None:\n        \"\"\"\n        Establish connections to a list of hosts\n\n        Args:\n            host_info_list (HostInfoList): a list of HostInfo objects\n            workdir (str): the directory where command is executed\n            env (dict): environment variables to propagate to hosts\n        \"\"\"\n        for hostinfo in host_info_list:\n            master_send_conn, worker_recv_conn = Pipe()\n            master_recv_conn, worker_send_conn = Pipe()\n            p = Process(target=run_on_host, args=(hostinfo, workdir, worker_recv_conn, worker_send_conn, env))\n            p.start()\n            self.processes[hostinfo.hostname] = p\n            self.master_recv_conns[hostinfo.hostname] = master_recv_conn\n            self.master_send_conns[hostinfo.hostname] = master_send_conn\n\n    def send(self, hostinfo: HostInfo, cmd: str) -> None:\n        \"\"\"\n        Send a command to a local/remote host.\n\n        Args:\n            hostinfo (HostInfo): host information\n            cmd (str): the command to execute\n        \"\"\"\n\n        assert hostinfo.hostname in self.master_send_conns, \\\n            f'{hostinfo} is not found in the current connections'\n        conn = self.master_send_conns[hostinfo.hostname]\n        conn.send(cmd)\n\n    def stop_all(self) -> None:\n        \"\"\"\n        Stop connections to all hosts.\n        \"\"\"\n\n        for hostname, conn in self.master_send_conns.items():\n            conn.send('exit')\n\n    def recv_from_all(self) -> dict:\n        \"\"\"\n        Receive messages from all hosts\n\n        Returns:\n            msg_from_node (dict): a dictionry which contains messages from each node\n        \"\"\"\n\n        msg_from_node = dict()\n        for hostname, conn in self.master_recv_conns.items():\n            msg_from_node[hostname] = conn.recv()\n        return msg_from_node\n", "path": "colossalai/cli/launcher/multinode_runner.py"}]}