Author: markt
Date: Sun Feb 16 18:27:16 2014
New Revision: 1568803
URL: http://svn.apache.org/r1568803
Log:
Avoid possible deadlock when one thread tries to close a connection while
another thread tries to write to it.
Modified:
tomcat/trunk/java/org/apache/tomcat/websocket/WsRemoteEndpointImplBase.java
tomcat/trunk/webapps/docs/changelog.xml
Modified:
tomcat/trunk/java/org/apache/tomcat/websocket/WsRemoteEndpointImplBase.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/tomcat/websocket/WsRemoteEndpointImplBase.java?rev=1568803&r1=1568802&r2=1568803&view=diff
==============================================================================
--- tomcat/trunk/java/org/apache/tomcat/websocket/WsRemoteEndpointImplBase.java
(original)
+++ tomcat/trunk/java/org/apache/tomcat/websocket/WsRemoteEndpointImplBase.java
Sun Feb 16 18:27:16 2014
@@ -249,6 +249,7 @@ public abstract class WsRemoteEndpointIm
MessagePart mp = new MessagePart(opCode, payload, last, handler, this);
+ boolean doWrite = false;
synchronized (messagePartLock) {
if (Constants.OPCODE_CLOSE == mp.getOpCode()) {
try {
@@ -260,30 +261,38 @@ public abstract class WsRemoteEndpointIm
}
if (messagePartInProgress) {
// When a control message is sent while another message is
being
- // the control message is queued. Chances are the subsequent
- // data message part will end up queued while the control
- // message is sent. The logic in this class (state machine,
- // EndMessageHanlder, TextMessageSendHandler) ensures that
there
- // will only ever be one data message part in the queue. There
- // could be multiple control messages in the queue.
+ // sent, the control message is queued. Chances are the
+ // subsequent data message part will end up queued while the
+ // control message is sent. The logic in this class (state
+ // machine, EndMessageHandler, TextMessageSendHandler) ensures
+ // that there will only ever be one data message part in the
+ // queue. There could be multiple control messages in the
queue.
// Add it to the queue
messagePartQueue.add(mp);
} else {
messagePartInProgress = true;
- writeMessagePart(mp);
+ doWrite = true;
}
}
+ if (doWrite) {
+ // Actual write has to be outside sync block to avoid possible
+ // deadlock between messagePartLock and writeLock in
+ // o.a.coyote.http11.upgrade.AbstractServletOutputStream
+ writeMessagePart(mp);
+ }
}
void endMessage(SendHandler handler, SendResult result) {
+ boolean doWrite = false;
+ MessagePart mpNext = null;
synchronized (messagePartLock) {
fragmented = nextFragmented;
text = nextText;
- MessagePart mpNext = messagePartQueue.poll();
+ mpNext = messagePartQueue.poll();
if (mpNext == null) {
messagePartInProgress = false;
} else if (!closed){
@@ -291,9 +300,15 @@ public abstract class WsRemoteEndpointIm
// sending a fragmented message closing the endpoint. If this
// happens, clearly there is no point trying to send the rest
of
// the message.
- writeMessagePart(mpNext);
+ doWrite = true;
}
}
+ if (doWrite) {
+ // Actual write has to be outside sync block to avoid possible
+ // deadlock between messagePartLock and writeLock in
+ // o.a.coyote.http11.upgrade.AbstractServletOutputStream
+ writeMessagePart(mpNext);
+ }
wsSession.updateLastActive();
Modified: tomcat/trunk/webapps/docs/changelog.xml
URL:
http://svn.apache.org/viewvc/tomcat/trunk/webapps/docs/changelog.xml?rev=1568803&r1=1568802&r2=1568803&view=diff
==============================================================================
--- tomcat/trunk/webapps/docs/changelog.xml (original)
+++ tomcat/trunk/webapps/docs/changelog.xml Sun Feb 16 18:27:16 2014
@@ -70,6 +70,14 @@
</fix>
</changelog>
</subsection>
+ <subsection name="WebSocket">
+ <changelog>
+ <fix>
+ Avoid a possible deadlock when one thread is shutting down a connection
+ while another thread is trying to write to it. (markt)
+ </fix>
+ </changelog>
+ </subsection>
<subsection name="Other">
<changelog>
<fix>
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