[erlang-bugs] Erlang SSH client hangs after some thousand requests

[Mario Santoro]

Hi Hans,
calling ssh_connection:adjust_window/3 with a large enough bytesize seems to overtake the problem.
Thanks a lot for your useful hint! :)
-Mario

-----Original Message-----
From: erlang-bugs-bounces@REDACTED [mailto:erlang-bugs-bounces@REDACTED] On Behalf Of Mario Santoro
Sent: 12 December 2016 18:25
To: Hans Nilsson R; erlang-bugs@REDACTED
Subject: Re: [erlang-bugs] Erlang SSH client hangs after some thousand requests

No, I don't. 
Should I?

-Mario

-----Original Message-----
From: Hans Nilsson R
Sent: 12 December 2016 18:23
To: Mario Santoro; erlang-bugs@REDACTED
Subject: Re: [erlang-bugs] Erlang SSH client hangs after some thousand requests

Do you call ssh_connection:adjust_window/3?

-Hans

On 12/12/2016 06:01 PM, Mario Santoro wrote:
> Hi all,
> 
> I wrote an Erlang ssh client module for running commands on a remote 
> host over an ssh connection.
> 
> The main calls to Erlang ssh library functions to setup the connection 
> are the following:
> 
> ssh:connect/4
> 
> ssh_connection:session_channel/2
> 
> ssh_connection:ptty_alloc/3
> 
> ssh_connection:shell/2
> 
>  
> 
> afterwards I'm issuing a command to remote host via:
> 
> ssh_connection:send/3
> 
>  
> 
> and receiving related reply in a msg loop, with the following format:
> 
> {ssh_cm, ConnectionRef, {data, ChannelId, Type, Data}}
> 
>  
> 
> Everything works fine and I'm able to issue commands and receive 
> responses correctly.
> 
>  
> 
> What I'm experiencing is a strange behavior on long lasting ssh
> sessions: when I start a long loop of
> 
> ssh send-receive requests, it seems like the client connection hangs 
> after a certain number or positive command requests (several 
> thousands),
> 
> waiting indefinitely for a reply, wherefrom it exits with timeout.
> 
> The only way to recover from this status is to disconnect and 
> reconnect to the server.
> 
>  
> 
> I tried with both Erlang OTP/17.x and OTP/18.x and towards remote 
> hosts running Linux and/or  Solaris OS, but the result is the same.
> 
>  
> 
> This behavior seems to be deterministic: given a command, it happens 
> after the same number of issued requests (e.g. for a trivial "pwd"
> command,
> 
> the client always hangs after 2510 tries!!).
> 
> This make me think as there's a limited receive buffer size somewhere 
> into the client ssh library or something similar (maybe something that 
> I should set at connection setup?);
> 
> since I'm quite newbie to Erlang, I'd very much appreciate if anyone 
> could help me to find out the reason for this behaviour.
> 
>  
> 
> Thanks in advance for your help!
> 
>  
> 
> Regards,
> 
> /Mario
> 
>  
> 
>  
> 
>  
> 
> Ericsson <http://www.ericsson.com/>
> 
> *MARIO SANTORO *
> Service Project Manager
> Region Mediterranean
> RMED ITC CU SCM SL AIB DMO
> 
> 
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> 
> 
> 
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