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https://issues.apache.org/jira/browse/SSHD-781?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16222501#comment-16222501
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Goldstein Lyor commented on SSHD-781:
-------------------------------------
As far as your question - I believe that you understood correctly. Sending the
heartbeat (a.k.a. "keep-alive") message only keeps the connection alive as far
as the server is concerned. However, sine there is no response to the message,
if there is no incoming traffic from the server to the client, then
{{NIO_READ_TIMEOUT}} will eventually expire on the client side. Therefore, to
avoid that either increase this timeout or do something that you know will
trigger some (valid) server response and thus reset the read timeout. In a side
note, I find it curious that code opens a connection and then does not use for
extended periods of time - one usually opens a connection in order to use it:
send a commend, interact with the shell, do some SCP/SFTP file transfer, etc...
In this case, perhaps run some periodic "harmless" command - e.g., {{echo
"hello there I am still alive"}} - before the read timeout expires.
> The heartbeat task of client not support keepalive function well
> ----------------------------------------------------------------
>
> Key: SSHD-781
> URL: https://issues.apache.org/jira/browse/SSHD-781
> Project: MINA SSHD
> Issue Type: Question
> Affects Versions: 1.4.0, 1.6.0
> Environment: Any environment
> Reporter: MayDay
> Assignee: Guillaume Nodet
> Labels: test
> Fix For: 1.7.0
>
>
>
> The heartbeat request of sshClient is a SSH_MSG_GLOBAL_REQUEST, but
> the default buffer of heartbeat set false (see
> [ClientConnectService#sendHeartbeat|https://github.com/apache/mina-sshd/blob/693fa5d90f54676de6655954046a8a4f5d09728a/sshd-core/src/main/java/org/apache/sshd/client/session/ClientConnectionService.java])
> {code:java}
> buf.putBoolean(false);
> {code}
> The sshServer reponse the heartbeat by the
> [KeepAliveHandler|https://github.com/apache/mina-sshd/blob/693fa5d90f54676de6655954046a8a4f5d09728a/sshd-core/src/main/java/org/apache/sshd/server/global/KeepAliveHandler.java],
> then [AbstractConnectionService
> #sendGlobalResponse|https://github.com/apache/mina-sshd/blob/693fa5d90f54676de6655954046a8a4f5d09728a/sshd-core/src/main/java/org/apache/sshd/common/session/helpers/AbstractConnectionService.java].
> {code:java}
> boolean wantReply = buffer.getBoolean();
> {code}
> but if the buffer of heartbeat set false, then the sendGlobalResponse
> will not reponse sshClient {color:#205081}because of the wantReply is
> false{color} .(see [AbstractConnectionService
> #globalRequest|https://github.com/apache/mina-sshd/blob/693fa5d90f54676de6655954046a8a4f5d09728a/sshd-core/src/main/java/org/apache/sshd/common/session/helpers/AbstractConnectionService.java])
> {code:java}
> if (RequestHandler.Result.Replied.equals(result) || (!wantReply)) {
> return new AbstractIoWriteFuture(req, null) {
> {
> setValue(Boolean.TRUE);
> }
> };
> }
> {code}
> 1 、Is it a Bug(set the heartbeat buffer false default)? how the sshClient
> know the server is available when the server don't response.
> I have test it whth create a client with params (
> HEARTBEAT_INTERAL = 60
> IDLE_TIMEOUT = 300
> NIO_READ_TIMEOUT = 315)and a server, and the client will close seesion after
> the NIO_READ_TIMEOUT.
> 2、If the client reach the NIO_READ_TIMEOUT, then thows a
> {color:#8eb021}InterruptedByTimeoutException{color},and close the session.But
> the task of heratbeat not stoped, it will continue to run even though it will
> not send packet.See the
> [ClientConnectionService
> #startHeartBeat|https://github.com/apache/mina-sshd/blob/693fa5d90f54676de6655954046a8a4f5d09728a/sshd-core/src/main/java/org/apache/sshd/client/session/ClientConnectionService.java]
> {code:java}
> service.scheduleAtFixedRate(this::sendHeartBeat, interval, interval,
> TimeUnit.MILLISECONDS);
> {code}
> if the sshClient reopen a new session and close it many times,the number of
> invalid scheduling heartbeat task will become very large, it's not
> equitable.
>
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