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https://issues.apache.org/jira/browse/SSHD-1148?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17306830#comment-17306830
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Lyor Goldstein edited comment on SSHD-1148 at 3/23/21, 7:24 AM:
----------------------------------------------------------------
{quote}Despite being the operation being parallel executed, as both the
operation are parallelly executed, a single thread does the same operation
{quote}
It only seems this way - there is actually a +dedicated thread+ for each
{{SftpSubsystem}} instance running on the server side. The reason you see the
same thread name is because of this code:
{code:java}
public SftpSubsystem(ChannelSession channel, SftpSubsystemConfigurator
configurator) {
super(channel, configurator);
CloseableExecutorService executorService =
configurator.getExecutorService();
if (executorService == null) {
this.executorService =
ThreadUtils.newSingleThreadExecutor(getClass().getSimpleName());
} else {
this.executorService = executorService;
}
}
{code}
As you can see. the argument to {{ThreadUtils.newSingleThreadExecutor}} is the
class name - which is always {{SftpSubsystem}} - therefore when the executor
derives its name, it always gets the same result. Thanks for bringing this to
our intention - I will fix this.
{quote}is there any way to pass an executor thread pool to SshServer so we can
see different thread working parallelly.
{quote}
Not through {{SshServer}} but rather through the {{SftpSubsystemFactory}} - but
like I said, you do have threads working in parallel - it just doesn't look
like this - so I would not recommend it (unless you want to manage your own
pool for some reason)
{quote}sshdServer.setScheduledExecutorService(Executors.newScheduledThreadPool(5),
true);
Will this spawn 5 parallel threads, and will be shut down gracefully as the
boolean is set to true
{quote}
No - the scheduled executors are used for something else - e.g., idle timeout,
heartbeat
{quote}If it's a single thread model then if we use NioWorker threads as 2, and
the number of cores if I have 4 so total will be 6, so now as 1 core is
occupied with that single thread, will the remaining 5 cores will sit idle?
{quote}
(a) it definitely is +not+ a single thread model and (b) {{NioWorker}} threads
affect +all+ SSH sessions and their behavior and not just SFTP.
was (Author: lgoldstein):
{quote}Despite being the operation being parallel executed, as both the
operation are parallelly executed, a single thread does the same operation
{quote}
It only seems this way - there is actually a +dedicated thread+ for each
{{SftpSubsystem}} instance running on the server side. The reason you see the
same thread name is because of this code:
{code:java}
public SftpSubsystem(ChannelSession channel, SftpSubsystemConfigurator
configurator) {
super(channel, configurator);
CloseableExecutorService executorService =
configurator.getExecutorService();
if (executorService == null) {
this.executorService =
ThreadUtils.newSingleThreadExecutor(getClass().getSimpleName());
} else {
this.executorService = executorService;
}
}
{code}
As you can see. the argument to {{ThreadUtils.newSingleThreadExecutor}} is the
class name - which is always {{SftpSubsystem}} - therefore when the executor
derives its name, it always gets the same result. Thanks for bringing this to
our intention - I will fix this.
{quote}is there any way to pass an executor thread pool to SshServer so we can
see different thread working parallelly.
{quote}
No through {{SshServer}} but rather through the {{SftpSubsystemFactory}} - but
like I said, you do have threads working in parallel - it just doesn't look
like this - so I would not recommend it (unless you want to manage your own
pool for some reason)
{quote}sshdServer.setScheduledExecutorService(Executors.newScheduledThreadPool(5),
true);
Will this spawn 5 parallel threads, and will be shut down gracefully as the
boolean is set to true
{quote}
No - the scheduled executors are used for something else - e.g., idle timeout,
heartbeat
{quote}If it's a single thread model then if we use NioWorker threads as 2, and
the number of cores if I have 4 so total will be 6, so now as 1 core is
occupied with that single thread, will the remaining 5 cores will sit idle?
{quote}
(a) it definitely is +not+ a single thread model and (b) {{NioWorker}} threads
affect +all+ SSH sessions and their behavior and not just SFTP.
> Question on thread handling with IOservicefactory as NIO2
> ---------------------------------------------------------
>
> Key: SSHD-1148
> URL: https://issues.apache.org/jira/browse/SSHD-1148
> Project: MINA SSHD
> Issue Type: Question
> Reporter: Susmit Sarkar
> Assignee: Lyor Goldstein
> Priority: Major
>
> Hello Lyor/Team,
> I am laterally performing 2 PUT operations, one from ssh terminal and another
> from WinSCP. During the process, I am printing the thread name/id. For both
> the case, I am getting a thread name as:
> *sshd-SftpSubsystem-thread-1*
> Despite being the operation being parallel executed, as both the operation
> are parallelly executed, a single thread does the same operation may be
> because of 2 different sessions, is there any way to pass an executor thread
> pool to *SshServer* so we can see different thread working parallelly. May be
> my understanding is wrong, can you please guide me
> *sshdServer.setScheduledExecutorService(Executors.newScheduledThreadPool(5),
> true);*
> Will this spawn 5 parallel threads, and will be shut down gracefully as the
> boolean is set to *true*
> If it's a single thread model then if we use NioWorker threads as 2, and the
> number of cores if I have 4 so total will be 6, so now as 1 core is occupied
> with that single thread, will the remaining 5 cores will sit idle?
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