You have to hold the lock in order to do proper waits. You should use
HashMap and not Hashtable in this case (you already synchronized access
on Hashtable).
After a second look I could see a possible problem. Are you catching
Runtime exceptions too? Also this wouldn't be an API bug but Tomcat
bug. Do a search in bugzilla for it.
I think that when a client drops out before receiving any response then
your servlet should get an IOException on trying to write to the closed
stream. Are you getting this exception on trying to write to the closed
client?
d.
Lyubomir Pashov wrote:
Hello :-)
Does anybody knows if the described below problem is a Servlet's API bug, or maybe I make a mistake?
And... how to solve it?
I work on Windows 2000, the Java version is J2SE 1.4.0, and I use CodeGuide 4.0 for running my servlet's application.
Into the servlet's init() method I create an instance of a class which plays a role as an engine for processing the client's requests, and into the doPost(...) method I invoke relative (to the clients requests) methods from the engine's instance.
One of the engine's fields is a Hashtable object, which the clients populate with concrete requests.
In one of the engine's methods it is needed to to wait (using the wait( some_time ) ) for someone to fill into the Hashtable's object.
And, here is the problem: If a client, which request is into the described above engine's method, is been dropped down (unexpectedly), then after elapsing the waited time, the next exception occurs (and it cannot be caught in try/catch block):
------------------------------------------------------
java.lang.IllegalStateException: Current state = FLUSHED, new state = CODING_END
at java.nio.charset.CharsetEncoder.throwIllegalStateException(CharsetEncoder.java:933)
at java.nio.charset.CharsetEncoder.encode(CharsetEncoder.java:529)
at sun.nio.cs.StreamEncoder$CharsetSE.flushLeftoverChar(StreamEncoder.java:356)
at sun.nio.cs.StreamEncoder$CharsetSE.implClose(StreamEncoder.java:413)
at sun.nio.cs.StreamEncoder.close(StreamEncoder.java:158)
at java.io.OutputStreamWriter.close(OutputStreamWriter.java:222)
at java.io.PrintWriter.close(PrintWriter.java:137)
at org.apache.catalina.connector.ResponseBase.finishResponse(ResponseBase.java:482)
at org.apache.catalina.connector.HttpResponseBase.finishResponse(HttpResponseBase.java:236)
at org.apache.catalina.connector.http.HttpResponseImpl.finishResponse(HttpResponseImpl.java:288)
at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:1039)
at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:1107)
at java.lang.Thread.run(Thread.java:536)
-----------------------------------------------------------
And if needed, here is the engine's method:
----------------------------
public String getRequests(long parentPID, String forUser, String userId,
HttpServletRequest httpReq) {
String result;
try {
........
result = BChatConstants.GET_REQUESTS_REPLY + "\n";
Hashtable requests = null;
// in the next line, requestedData is a Hashtable object too
synchronized (requests = (Hashtable) requestedData.get(forUser)) {
if (requests.isEmpty()){
requests.wait(30000);
}
if (requests.isEmpty()) {
.........
} else {
.........
.........
}
}
return result;
}catch (Exception e) {
e.printStackTrace();
}
return result;
}
----------------------------
Thanks,
Lyubomir.
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