[GRIZZLY-597] OutputWriter#flushChannel() throws an exception
inadequately on a load test Created: 12/May/09 Updated: 11/Nov/11 Resolved: 17/Dec/09
Status:
Project:
Component/s:
Affects
Version/s:
Fix Version/s:
Resolved
grizzly
http
1.9.22
Type:
Reporter:
Resolution:
Labels:
Remaining
Estimate:
Time Spent:
Original
Estimate:
Environment:
Bug
carryel
Fixed
None
Not Specified
Attachments:
outputwriter_patch.jar
597
Issuezilla Id:
1.9.16
Priority:
Assignee:
Votes:
Major
grizzly-issues
0
Not Specified
Not Specified
Operating System: All
Platform: All
Description
When I sent many large packets to the remote server with
OutputWriter#flushChannel(), some packets could be lost with receiving the
following exception.
In the sender side,
java.io.IOException: Client disconnected
at com.sun.grizzly.util.OutputWriter.flushChannel(OutputWriter.java:124)
at GrizzlyTCPConnectorWrapper.send(GrizzlyTCPConnectorWrapper.java:61)
at GrizzlyTCPConnectorWrapper.send(GrizzlyTCPConnectorWrapper.java:44)
at GrizzlyNetworkManager.send(GrizzlyNetworkManager.java:218)
at GrizzlyNetworkManagerSendTest$2.run
(GrizzlyNetworkManagerSendTest.java:78)
at java.lang.Thread.run(Thread.java:717)
First, I thought that the server might close the client's connection because of
overflow, and the exception log said "Client disconnected", so I tuned server's
params.
But this error could not be resolved unfortunately.
When I tried to debug the server and client, I was very confused because the
connection was still alive and had no problems.
I used the OutputWrite for sending packets like this.
long timeout = 30000; // 30sec
...
OutputWriter.flushChannel( connectorHandler.getUnderlyingChannel(), message,
timeout);
...
Intuitively, I thought that flushChannel() would retry and wait for at least
the timeout if the server and client were busy.
But I saw the code, I could know that my thought was wrong.
Here is OutputWriter#flushChannel(SelectableChannel channel, ByteBuffer bb,
long writeTimeout)' code.
public static long flushChannel(SelectableChannel channel, ByteBuffer bb, long
writeTimeout) throw IOExceiton{
...
try{
WritableByteChannel writableChannel = (WritableByteChannel) channel;
while( bb.hasRemaining() ) {
len = writableChannel.write(bb);
if( len>0 )
{ attempts = 0; nWrite += len; }
else {
attempts++;
...
if(writeSelector.select(writeTimeout) == 0)
{ ------ (1) if(attempts > 2) throw new IOException("Client disconnected"); ------ (2) }
}
}
} catch( IOException ex )
{ ... } finally { ... }
return nWrite;
}
(1) When I tested, Selector#select() could return 0 though it was not timed
out. Then OutputWriter#flushChannel()'s writeTimeout is perhaps meaningless.
Actually above the wrong IOException will be thrown before
OutputWriter#flushChannel() waits for writeTimeout and tries to send the
message again. Of course, attempts has 2 limit value, but I think that it is
not enough.
(2) I think that "Client disconnected"'s message is wrong. If client
disconnected, the following exception will usually be thrown rather than above
(2).
java.nio.channels.ClosedChannelException
at sun.nio.ch.SocketChannelImpl.ensureWriteOpen
(SocketChannelImpl.java:236)
at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:434)
at com.sun.grizzly.util.OutputWriter.flushChannel(OutputWriter.java:106)
at GrizzlyTCPConnectorWrapper.send(GrizzlyTCPConnectorWrapper.java:61)
at GrizzlyTCPConnectorWrapper.send(GrizzlyTCPConnectorWrapper.java:44)
at GrizzlyNetworkManager.send(GrizzlyNetworkManager.java:218)
at GrizzlyNetworkManagerSendTest$2.run
(GrizzlyNetworkManagerSendTest.java:78)
at java.lang.Thread.run(Thread.java:717)
I think that "Client is busy or timed out"'s message is better.
So, I tried to make the patch experimentally.
Here is the diff
Index: com/sun/grizzly/util/OutputWriter.java
===================================================================
— com/sun/grizzly/util/OutputWriter.java (revision 3143)
+++ com/sun/grizzly/util/OutputWriter.java (working copy)
@@ -100,12 +100,14 @@
int attempts = 0;
int nWrite = 0;
int len = -1;
+ long elapsedTime = 0;
try {
WritableByteChannel writableChannel = (WritableByteChannel)
channel;
while ( bb.hasRemaining() ) {
len = writableChannel.write(bb);
if (len > 0)
{ attempts = 0; + elapsedTime = 0; nWrite += len; } else { attempts++; @@ -119,10 +121,12
@@ SelectionKey.OP_WRITE); }
+ long startTime = System.currentTimeMillis();
if (writeSelector.select(writeTimeout) == 0) { - if (attempts > 2) - throw new
IOException("Client disconnected"); - }
+ elapsedTime += (System.currentTimeMillis() startTime);
+ if (attempts > 2 && ( writeTimeout > 0 && elapsedTime
>= writeTimeout ) )
+ throw new IOException("Client is busy or timed
out");
+}
}
}
} catch (IOException ex){
@@ -198,11 +202,13 @@
long nWrite = 0;
long len = -1;
+ long elapsedTime = 0;
try {
while (nWrite < totalBytes ) {
len = socketChannel.write(bb);
if (len > 0){ attempts = 0;+ elapsedTime = 0; nWrite += len; }
else {
if ( writeSelector == null ){
@@ -215,10 +221,12 @@
key = socketChannel.register(writeSelector,
SelectionKey.OP_WRITE);

+
+ long startTime = System.currentTimeMillis();
if (writeSelector.select(writeTimeout) == 0)
{ - if (attempts > 2) - throw new IOException("Client disconnected"); + elapsedTime +=
(System.currentTimeMillis() - startTime); + if (attempts > 2 && ( writeTimeout > 0 &&
elapsedTime >= writeTimeout ) ) + throw new IOException("Client is busy or timed
out"); }
}
}
@@ -298,11 +306,13 @@
Selector writeSelector = null;
int attempts = 0;
int nWrite = 0;
+ long elapsedTime = 0;
try {
while ( bb.hasRemaining() ) {
int len = datagramChannel.send(bb,socketAddress);
if (len > 0){ attempts = 0; + elapsedTime = 0; nWrite += len; } else {
if ( writeSelector == null ){
@@ -315,10 +325,12 @@
key = datagramChannel.register(writeSelector,
SelectionKey.OP_WRITE);
+
+ long startTime = System.currentTimeMillis();
if (writeSelector.select(writeTimeout) == 0) {- if (attempts > 2)- throw new
IOException("Client disconnected");+ elapsedTime += (System.currentTimeMillis() startTime);+ if (attempts > 2 && ( writeTimeout > 0 && elapsedTime >= writeTimeout
) )+ throw new IOException("Client is busy or timed out"); }
else
{ attempts--; }
Comments
Comment by carryel [ 12/May/09 ]
Created an attachment (id=68)
I attached the proposed patch and diff
Comment by jfarcand [ 13/May/09 ]
Patch applied. Thanks YOU!
Sending java/com/sun/grizzly/util/OutputWriter.java
Transmitting file data .
Committed revision 3191.
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