On 28.01.2016 18:38, Maxim Neshcheret wrote:
I have a problem with my java application related to HTTP communication.
Application description:
1. Client – server. Server is running in servlet container. We use Tomcat.
Client use java HTTP library to communicate with the server.
2. When client establish connection to the server it sends GET request
(keepalive) and server creates AsyncContext for the client with 10 days timeout.
3. After connection established server periodically sends data to the
client using AsyncContext and on the client side there is special thread which
reads and processes the data.
[ snip ...]
Usually this code works fine but it there is no data from server to client for
1 day and after 24 hours (can be 16 or 12) data appears, server cannot send
data to the client.
In the log there is no error. It is written that everything flushed but client
still waiting for data in “final String line = reader.readLine();”
When 2nd portion of data is sent by the server, then during flush I see the
following error
2016-01-26 00:00:00,051|INFO |GWNotify-2/50 |ClientAbort
2016-01-26 00:00:00,051|TRACE|GWNotify-2/50
|ClientAbortException:java.io.IOException: APR error: -32
org.apache.catalina.connector.ClientAbortException: java.io.IOException: APR
error: -32
[snip ...]
Hi.
I am unqualified to check your code, but a first question would be : where is the Client,
and where is the Server and what is the connection between them like ?
And the reason for the question is : it is not at all unusual, that any kind of network
connection would be interrupted at some point over a 24-hour period, specially if nothing
is sent over that connection for a long time.
When a connection "disappears", TCP sends no signal to either the client or the server,
and an error will only be caught, if one of the parties tries to write to the (now gone)
connection (which seems to be what happens above, when the server tries to write to the
Client, and gets a "client is no longer there" exception).
If you want to avoid this, you will have to handle this in your code. You cannot just
expect the connection to be alive no matter what.
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