Should I increase connectionUploadTimeout value

[Yuval Schwartz]

Tomcat: 8.0.22
Java: jdk1.8.0_05
Server: Amazon Linux

Hello,

I recently saw an IOFileUploadException on my server:

org.apache.tomcat.util.http.fileupload.FileUploadBase$IOFileUploadException:
Processing of multipart/form-data request failed. Timeout attempting to
read dat
a from the socket

And later, I get this exception:
org.apache.tomcat.util.http.fileupload.MultipartStream$MalformedStreamException:
Stream ended unexpectedly

I allow images to be uploaded in a multipart form.

I don't allow uploads greater than 1 MB.

Presently, my connector element is set up with only a connectionTimeout
attribute (set at 20 seconds) and without a connectionUploadTimeout
attribute.

I was wondering if it's necessary to set up a connectionUploadTimeout time
greater than 20 seconds for such small file uploads? Or is it something
else that caused this timeout?

Thank you.

[André Warnier (tomcat)]

Hi.

Post by Yuval Schwartz
Tomcat: 8.0.22
Java: jdk1.8.0_05
Server: Amazon Linux
Hello,
Processing of multipart/form-data request failed. Timeout attempting to
read dat
a from the socket
Stream ended unexpectedly
I allow images to be uploaded in a multipart form.
I don't allow uploads greater than 1 MB.
Presently, my connector element is set up with only a connectionTimeout
attribute (set at 20 seconds) and without a connectionUploadTimeout
attribute.
I was wondering if it's necessary to set up a connectionUploadTimeout time
greater than 20 seconds for such small file uploads? Or is it something
else that caused this timeout?

1) specifically : such a timeout could occur "naturally" if the connection of the client
to the server is interrupted, for whatever reason. You did not mention what the client is
seeing in that case, you only described what you see in the log from the server side.
(That's ok, you probably don't know anyway).
Maybe the client (the person at the uploading form side) decided to interrupt the upload,
by navigating to some other page. If there are other "devices" in-between (routers,
firewalls, proxies,..) (as there most probably are, nowadays) they may maintain their
connection to the server for a while, even if the original client has gone. Tomcat would
thus not see the broken connection immediately, it would still be waiting for more data to
arrive on the connection, until this timeout kicks in.
Increasing the timeout in this case, would just mean that you are blocking a tomcat
resource for a while longer, for no real good reason since the client is already gone.

In short, my opinion : if you only see this once in a while in your logs, I would not
worry about it. It would be different if your "clients" started complaining about having
their uploads interrupted regularly. But then you could ask them for exactly what they are
seeing in the browser as an error, and at exactly what time; and then you could have
another look at the log for that timestamp, to see if it is the same case as above.


2) generally : I must say that it is not very clear in the on-line documentation, at
https://tomcat.apache.org/tomcat-8.5-doc/config/http.html#Standard_Implementation
-> Standard Implementation -> connectionUploadTimeout
(and also in the similar 7.0 docs)
what exactly this timeout applies to. Is it
- the timeout before the client actually *starts* sending *any* request body data for this
upload ?
- or a timeout which applies at any time tomcat is trying to read *some* (a chunk of) data
for this part of the multipart/form-data post, after already reading some data ?
Similarly for the "disableUploadTimeout" attribute.
I believe that the confusion may have to do with the usage of the term "data upload"
there. It seems that, maybe, using "request body" may have been more appropriate throughout.
(Because in a way, any HTTP POST is a "data upload", even when it is not a
multipart/form-data and/or not a file).



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[Yuval Schwartz]

Hello Andre,

Thanks a lot.

Post by André Warnier (tomcat)
Hi.

Post by Yuval Schwartz
Tomcat: 8.0.22
Java: jdk1.8.0_05
Server: Amazon Linux
Hello,
org.apache.tomcat.util.http.fileupload.FileUploadBase$IOFile
Processing of multipart/form-data request failed. Timeout attempting to
read dat
a from the socket
org.apache.tomcat.util.http.fileupload.MultipartStream$Malfo
Stream ended unexpectedly
I allow images to be uploaded in a multipart form.
I don't allow uploads greater than 1 MB.
Presently, my connector element is set up with only a connectionTimeout
attribute (set at 20 seconds) and without a connectionUploadTimeout
attribute.
I was wondering if it's necessary to set up a connectionUploadTimeout time
greater than 20 seconds for such small file uploads? Or is it something
else that caused this timeout?

1) specifically : such a timeout could occur "naturally" if the connection
of the client to the server is interrupted, for whatever reason. You did
not mention what the client is seeing in that case, you only described what
you see in the log from the server side.
(That's ok, you probably don't know anyway).

I don't know at this time. But I will try to find out.

Post by André Warnier (tomcat)
Maybe the client (the person at the uploading form side) decided to
interrupt the upload, by navigating to some other page. If there are other
"devices" in-between (routers, firewalls, proxies,..) (as there most
probably are, nowadays) they may maintain their connection to the server
for a while, even if the original client has gone. Tomcat would thus not
see the broken connection immediately, it would still be waiting for more
data to arrive on the connection, until this timeout kicks in.
Increasing the timeout in this case, would just mean that you are blocking
a tomcat resource for a while longer, for no real good reason since the
client is already gone.
In short, my opinion : if you only see this once in a while in your logs,
I would not worry about it. It would be different if your "clients" started
complaining about having their uploads interrupted regularly. But then you
could ask them for exactly what they are seeing in the browser as an error,
and at exactly what time; and then you could have another look at the log
for that timestamp, to see if it is the same case as above.

Good point.

Post by André Warnier (tomcat)
2) generally : I must say that it is not very clear in the on-line documentation, at
https://tomcat.apache.org/tomcat-8.5-doc/config/http.html#
Standard_Implementation
-> Standard Implementation -> connectionUploadTimeout
(and also in the similar 7.0 docs)
what exactly this timeout applies to. Is it
- the timeout before the client actually *starts* sending *any* request
body data for this upload ?
- or a timeout which applies at any time tomcat is trying to read *some*
(a chunk of) data for this part of the multipart/form-data post, after
already reading some data ?
Similarly for the "disableUploadTimeout" attribute.
I believe that the confusion may have to do with the usage of the term
"data upload" there. It seems that, maybe, using "request body" may have
been more appropriate throughout.
(Because in a way, any HTTP POST is a "data upload", even when it is not a
multipart/form-data and/or not a file).
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