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https://issues.apache.org/jira/browse/SSHD-1173?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17615261#comment-17615261
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Kirk Rasmussen edited comment on SSHD-1173 at 10/10/22 9:01 PM:
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BTW when I said it would be "nightmarish" I simply meant that our customer's 
typically outsource managed file transfer to 3rd party companies and have 
little idea what SFTP protocol even is so trying to explain why suddenly their 
files aren't being transferred anymore because the "window adjustment message" 
isn't being sent their eyes will just glaze over. Prior to this we were using 
JSch which didn't have this problem and we got caught at the last minute 
unfortunately - they have no idea nor do they need to know what SFTP library we 
use.

Your explanation makes sense to me though thanks for all your help! [~twolf] 


was (Author: JIRAUSER296597):
BTW when I said it would be "nightmarish" I simply meant that customer's 
typically outsource managed file transfer to 3rd party companies and have 
little idea what SFTP protocol even is so trying to explain why suddenly their 
files aren't being transferred anymore because the "window adjustment message" 
isn't being sent their eyes will just glaze over. Prior to this we were using 
JSch which didn't have this problem and we got caught at the last minute 
unfortunately - they have no idea nor do they need to know what SFTP library we 
use.

Your explanation makes sense to me though thanks for all your help! [~twolf] 

> SFTP worker threads got stuck while processing PUT methods against one 
> specific SFTP server
> -------------------------------------------------------------------------------------------
>
>                 Key: SSHD-1173
>                 URL: https://issues.apache.org/jira/browse/SSHD-1173
>             Project: MINA SSHD
>          Issue Type: Question
>    Affects Versions: 2.6.0
>            Reporter: Pavel Pohner
>            Priority: Critical
>              Labels: SFTP, mina, sshd
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> Hey guys,
> Recently I've encountered one remote SFTP server, that causes SFTP worker 
> threads to enter TIMED_WAITING state, from which they do not recover. Please, 
> take a look into this thread dump:
> {code:java}
> SFTP-worker-3 #2155 prio=5 os_prio=0 cpu=61692.09ms elapsed=1136151.86s 
> tid=0x00007fe41c005800 nid=0x18808 in Object.wait()  
> [0x00007fe145b1d000]SFTP-worker-3" #2155 prio=5 os_prio=0 cpu=61692.09ms 
> elapsed=1136151.86s tid=0x00007fe41c005800 nid=0x18808 in Object.wait()  
> [0x00007fe145b1d000]   java.lang.Thread.State: TIMED_WAITING (on object 
> monitor) at java.lang.Object.wait(java.base@11.0.10/Native Method) - waiting 
> on <no object reference available> at 
> org.apache.sshd.common.future.DefaultSshFuture.await0(DefaultSshFuture.java:69)
>  - waiting to re-lock in wait() <0x00000006e3bbc420> (a 
> org.apache.sshd.common.channel.IoWriteFutureImpl) at 
> org.apache.sshd.common.future.AbstractSshFuture.verifyResult(AbstractSshFuture.java:109)
>  at 
> org.apache.sshd.common.io.AbstractIoWriteFuture.verify(AbstractIoWriteFuture.java:39)
>  at 
> org.apache.sshd.common.io.AbstractIoWriteFuture.verify(AbstractIoWriteFuture.java:30)
>  at 
> org.apache.sshd.common.future.VerifiableFuture.verify(VerifiableFuture.java:43)
>  at 
> org.apache.sshd.sftp.client.impl.DefaultSftpClient.send(DefaultSftpClient.java:292)
>  at 
> org.apache.sshd.sftp.client.impl.SftpOutputStreamAsync.flush(SftpOutputStreamAsync.java:210)
>  at 
> org.apache.sshd.sftp.client.impl.SftpOutputStreamAsync.write(SftpOutputStreamAsync.java:141)
>  at java.io.InputStream.transferTo(java.base@11.0.10/InputStream.java:705) at 
> com.mina.command.Put.replyInto(Put.java:55) at 
> com.sftpserver.MinaSftpHandler.channelReadInternal(MinaSftpHandler.java:251) 
> at 
> com.sftpserver.MinaSftpHandler.lambda$channelRead$0(MinaSftpHandler.java:125) 
> at com.sftpserver.MinaSftpHandler$$Lambda$392/0x0000000800764040.run(Unknown 
> Source) at 
> java.util.concurrent.Executors$RunnableAdapter.call(java.base@11.0.10/Executors.java:515)
>  at 
> java.util.concurrent.FutureTask.run(java.base@11.0.10/FutureTask.java:264) at 
> java.util.concurrent.ThreadPoolExecutor.runWorker(java.base@11.0.10/ThreadPoolExecutor.java:1128)
>  at 
> java.util.concurrent.ThreadPoolExecutor$Worker.run(java.base@11.0.10/ThreadPoolExecutor.java:628)
>  at java.lang.Thread.run(java.base@11.0.10/Thread.java:834)
> {code}
> Seems like the thread is waiting for lock in 
> org.apache.sshd.common.future.DefaultSshFuture.await0(DefaultSshFuture.java), 
> I'm currently not sure what thread holds the lock and why it's not ever 
> released.
> Also, I'm not able to reproduce this, but it constantly happens to all the 
> PUT methods targeting one specific remote server (which I don't own), so I 
> suppose there would be something odd with the remote server, but it doesn't 
> mean, that we shouldn't be able to deal with that.
> Have you ever seen such behavior? Could it be Mina sshd's bug? (seems like 
> verify() in 
> org.apache.sshd.sftp.client.impl.DefaultSftpClient.send(DefaultSftpClient.java:292)
>  is called without any timeout, which then defaults to LONG.MAX here: at 
> org.apache.sshd.common.future.VerifiableFuture.verify(VerifiableFuture.java:43),
>  shouldn't we have configurable timeout here? or what's the point of default 
> timeout? what are we really waiting for in at 
> org.apache.sshd.common.future.DefaultSshFuture.await0(DefaultSshFuture.java:69)?)



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