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https://issues.apache.org/jira/browse/SSHD-1173?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17615236#comment-17615236
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Kirk Rasmussen edited comment on SSHD-1173 at 10/10/22 5:52 PM:
----------------------------------------------------------------
Here's simple test harness I was using to debug remote server.
{code:java}
private static void write(final SftpClient client,
final String path,
final int size,
final int bufferSize) throws IOException {
System.out.printf("write(\"%s\", %d, %d)%n", path, size, bufferSize);
final Path uploadFile = createUploadFile(size);
final StopWatch stopWatch = new StopWatch();
stopWatch.start();
try (InputStream inputStream = Files.newInputStream(uploadFile);
OutputStream outputStream = client.write(
path,
bufferSize,
SftpClient.OpenMode.Write, SftpClient.OpenMode.Create,
SftpClient.OpenMode.Truncate)) {
final byte[] buffer = new byte[16 * 1_024];
int sent = 0;
int read;
while ((read = inputStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, read);
sent += read;
System.out.print(".");
// System.out.printf("\tsent=%-15d (%3.02f%%) :: %s%n", sent,
(double)sent/size * 100.0, stopWatch.formatTime());
}
System.out.printf("%n\tTotal: %s%n", stopWatch.formatTime());
} catch (SftpException ex) {
System.out.printf("write(\"%s\") failed: %s (%d)%n", path, ex,
ex.getStatus());
}
}
{code}
It would deadlock w/o the SftpModuleProperties.CHUNK_IF_WINDOW_LESS_THAN_PACKET
setting , e.g.
{code:java}
write("/sftp-test.txt", 1048576, 0)
sent=1024 (0.10%) :: 00:00:00.126
sent=2048 (0.20%) :: 00:00:00.140
sent=3072 (0.29%) :: 00:00:00.140
sent=4096 (0.39%) :: 00:00:00.140
sent=5120 (0.49%) :: 00:00:00.140
sent=6144 (0.59%) :: 00:00:00.140
sent=7168 (0.68%) :: 00:00:00.140
sent=8192 (0.78%) :: 00:00:00.140
sent=9216 (0.88%) :: 00:00:00.141
sent=10240 (0.98%) :: 00:00:00.141
sent=11264 (1.07%) :: 00:00:00.141
sent=12288 (1.17%) :: 00:00:00.141
sent=13312 (1.27%) :: 00:00:00.141
sent=14336 (1.37%) :: 00:00:00.141
sent=15360 (1.46%) :: 00:00:00.141
sent=16384 (1.56%) :: 00:00:00.141
sent=17408 (1.66%) :: 00:00:00.142
sent=18432 (1.76%) :: 00:00:00.142
sent=19456 (1.86%) :: 00:00:00.142
sent=20480 (1.95%) :: 00:00:00.142
sent=21504 (2.05%) :: 00:00:00.142
sent=22528 (2.15%) :: 00:00:00.142
sent=23552 (2.25%) :: 00:00:00.142
sent=24576 (2.34%) :: 00:00:00.142
sent=25600 (2.44%) :: 00:00:00.143
sent=26624 (2.54%) :: 00:00:00.143
sent=27648 (2.64%) :: 00:00:00.143
sent=28672 (2.73%) :: 00:00:00.143
sent=29696 (2.83%) :: 00:00:00.143
sent=30720 (2.93%) :: 00:00:00.143
sent=31744 (3.03%) :: 00:00:00.143
{code}
I don't have the full stack trace unfortunately and I lost access to the server
but here's a partial grab (which is very similar to the original reporter's)
{code:java}
Caused by: java.io.InterruptedIOException:
IoWriteFutureImpl[SftpChannelSubsystem[id=0,
recipient=0]-ClientSessionImpl[cpq_dump@/10.18.242.4:8080][sftp][SSH_MSG_CHANNEL_DATA]]:
Interrupted after 37644419 msec.
at
org.apache.sshd.common.future.DefaultSshFuture.lambda$await0$0(DefaultSshFuture.java:74)
~[sshd-common-2.8.0.jar:2.8.0]
at
org.apache.sshd.common.future.AbstractSshFuture.formatExceptionMessage(AbstractSshFuture.java:185)
~[sshd-common-2.8.0.jar:2.8.0]
at
org.apache.sshd.common.future.DefaultSshFuture.await0(DefaultSshFuture.java:73)
~[sshd-common-2.8.0.jar:2.8.0]
at
org.apache.sshd.common.future.AbstractSshFuture.verifyResult(AbstractSshFuture.java:109)
~[sshd-common-2.8.0.jar:2.8.0]
at
org.apache.sshd.common.io.AbstractIoWriteFuture.verify(AbstractIoWriteFuture.java:39)
~[sshd-common-2.8.0.jar:2.8.0]
at
org.apache.sshd.common.io.AbstractIoWriteFuture.verify(AbstractIoWriteFuture.java:30)
~[sshd-common-2.8.0.jar:2.8.0]
at
org.apache.sshd.common.future.VerifiableFuture.verify(VerifiableFuture.java:43)
~[sshd-common-2.8.0.jar:2.8.0]
at
org.apache.sshd.sftp.client.impl.DefaultSftpClient.send(DefaultSftpClient.java:301)
~[sshd-sftp-2.8.0.jar:2.8.0]
at
org.apache.sshd.sftp.client.impl.SftpOutputStreamAsync.flush(SftpOutputStreamAsync.java:207)
~[sshd-sftp-2.8.0.jar:2.8.0]
at
org.apache.sshd.sftp.client.impl.SftpOutputStreamAsync.write(SftpOutputStreamAsync.java:138)
~[sshd-sftp-2.8.0.jar:2.8.0]
{code}
With the SftpModuleProperties.CHUNK_IF_WINDOW_LESS_THAN_PACKET setting it no
longer deadlocks but DefaultSftpClient still has potential as this waits
forever.
{code:java}
writeFuture.verify(); {code}
When I didn't have the SftpModuleProperties.CHUNK_IF_WINDOW_LESS_THAN_PACKET
setting enabled I noticed even after the socket was closed the main thread was
still deadlocked on the above. To be clear when using the setting everything
is 100% fine no deadlock of any kind.
BTW I did find there was one other workaround I found that worked ok was using
a custom bufferSize. I had to play around until I found a buffer size that
didn't deadlock (e.g. 15_000 was ok but 20_000 was not) so it wasn't as
reliable as SftpModuleProperties.CHUNK_IF_WINDOW_LESS_THAN_PACKET .
was (Author: JIRAUSER296597):
Here's simple test harness I was using to debug remote server.
{code:java}
private static void write(final SftpClient client,
final String path,
final int size,
final int bufferSize) throws IOException {
System.out.printf("write(\"%s\", %d, %d)%n", path, size, bufferSize);
final Path uploadFile = createUploadFile(size);
final StopWatch stopWatch = new StopWatch();
stopWatch.start();
try (InputStream inputStream = Files.newInputStream(uploadFile);
OutputStream outputStream = client.write(
path,
bufferSize,
SftpClient.OpenMode.Write, SftpClient.OpenMode.Create,
SftpClient.OpenMode.Truncate)) {
final byte[] buffer = new byte[16 * 1_024];
int sent = 0;
int read;
while ((read = inputStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, read);
sent += read;
System.out.print(".");
// System.out.printf("\tsent=%-15d (%3.02f%%) :: %s%n", sent,
(double)sent/size * 100.0, stopWatch.formatTime());
}
System.out.printf("%n\tTotal: %s%n", stopWatch.formatTime());
} catch (SftpException ex) {
System.out.printf("write(\"%s\") failed: %s (%d)%n", path, ex,
ex.getStatus());
}
}
{code}
It would deadlock w/o the SftpModuleProperties.CHUNK_IF_WINDOW_LESS_THAN_PACKET
setting , e.g.
{code:java}
write("/sftp-test.txt", 1048576, 0)
sent=1024 (0.10%) :: 00:00:00.126
sent=2048 (0.20%) :: 00:00:00.140
sent=3072 (0.29%) :: 00:00:00.140
sent=4096 (0.39%) :: 00:00:00.140
sent=5120 (0.49%) :: 00:00:00.140
sent=6144 (0.59%) :: 00:00:00.140
sent=7168 (0.68%) :: 00:00:00.140
sent=8192 (0.78%) :: 00:00:00.140
sent=9216 (0.88%) :: 00:00:00.141
sent=10240 (0.98%) :: 00:00:00.141
sent=11264 (1.07%) :: 00:00:00.141
sent=12288 (1.17%) :: 00:00:00.141
sent=13312 (1.27%) :: 00:00:00.141
sent=14336 (1.37%) :: 00:00:00.141
sent=15360 (1.46%) :: 00:00:00.141
sent=16384 (1.56%) :: 00:00:00.141
sent=17408 (1.66%) :: 00:00:00.142
sent=18432 (1.76%) :: 00:00:00.142
sent=19456 (1.86%) :: 00:00:00.142
sent=20480 (1.95%) :: 00:00:00.142
sent=21504 (2.05%) :: 00:00:00.142
sent=22528 (2.15%) :: 00:00:00.142
sent=23552 (2.25%) :: 00:00:00.142
sent=24576 (2.34%) :: 00:00:00.142
sent=25600 (2.44%) :: 00:00:00.143
sent=26624 (2.54%) :: 00:00:00.143
sent=27648 (2.64%) :: 00:00:00.143
sent=28672 (2.73%) :: 00:00:00.143
sent=29696 (2.83%) :: 00:00:00.143
sent=30720 (2.93%) :: 00:00:00.143
sent=31744 (3.03%) :: 00:00:00.143
{code}
I don't have the full stack trace unfortunately and I lost access to the server
but here's a partial grab (which is very similar to the original reporter's)
{code:java}
Caused by: java.io.InterruptedIOException:
IoWriteFutureImpl[SftpChannelSubsystem[id=0,
recipient=0]-ClientSessionImpl[cpq_dump@/10.18.242.4:8080][sftp][SSH_MSG_CHANNEL_DATA]]:
Interrupted after 37644419 msec.
at
org.apache.sshd.common.future.DefaultSshFuture.lambda$await0$0(DefaultSshFuture.java:74)
~[sshd-common-2.8.0.jar:2.8.0]
at
org.apache.sshd.common.future.AbstractSshFuture.formatExceptionMessage(AbstractSshFuture.java:185)
~[sshd-common-2.8.0.jar:2.8.0]
at
org.apache.sshd.common.future.DefaultSshFuture.await0(DefaultSshFuture.java:73)
~[sshd-common-2.8.0.jar:2.8.0]
at
org.apache.sshd.common.future.AbstractSshFuture.verifyResult(AbstractSshFuture.java:109)
~[sshd-common-2.8.0.jar:2.8.0]
at
org.apache.sshd.common.io.AbstractIoWriteFuture.verify(AbstractIoWriteFuture.java:39)
~[sshd-common-2.8.0.jar:2.8.0]
at
org.apache.sshd.common.io.AbstractIoWriteFuture.verify(AbstractIoWriteFuture.java:30)
~[sshd-common-2.8.0.jar:2.8.0]
at
org.apache.sshd.common.future.VerifiableFuture.verify(VerifiableFuture.java:43)
~[sshd-common-2.8.0.jar:2.8.0]
at
org.apache.sshd.sftp.client.impl.DefaultSftpClient.send(DefaultSftpClient.java:301)
~[sshd-sftp-2.8.0.jar:2.8.0]
at
org.apache.sshd.sftp.client.impl.SftpOutputStreamAsync.flush(SftpOutputStreamAsync.java:207)
~[sshd-sftp-2.8.0.jar:2.8.0]
at
org.apache.sshd.sftp.client.impl.SftpOutputStreamAsync.write(SftpOutputStreamAsync.java:138)
~[sshd-sftp-2.8.0.jar:2.8.0]
{code}
With the SftpModuleProperties.CHUNK_IF_WINDOW_LESS_THAN_PACKET setting it no
longer deadlocks but DefaultSftpClient still has potential as this waits
forever.
{code:java}
writeFuture.verify(); {code}
When I didn't have the SftpModuleProperties.CHUNK_IF_WINDOW_LESS_THAN_PACKET
setting enabled I noticed even after the socket was closed the main thread was
still deadlocked on the above.
I did find there was one other workaround I found that worked ok was using a
custom bufferSize (e.g. 15_000 was ok but 20_000 was not). I had to play around
until I found a buffer size that didn't deadlock so it wasn't as reliable as
SftpModuleProperties.CHUNK_IF_WINDOW_LESS_THAN_PACKET .
> 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([email protected]/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([email protected]/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([email protected]/Executors.java:515)
> at
> java.util.concurrent.FutureTask.run([email protected]/FutureTask.java:264) at
> java.util.concurrent.ThreadPoolExecutor.runWorker([email protected]/ThreadPoolExecutor.java:1128)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run([email protected]/ThreadPoolExecutor.java:628)
> at java.lang.Thread.run([email protected]/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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