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https://issues.apache.org/jira/browse/JCS-41?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12585658#action_12585658
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Niall Gallagher commented on JCS-41:
------------------------------------
Yes JCS does set the timeout for all RMI connections, it's a JVM-wide thing.
It's not a problem for us that JCS sets this for the whole JVM though.
It looks like -Dsun.rmi.transport.tcp.readTimeout=xxx achieves the same thing
as the existing JCS code actually. "The value is passed to
java.net.Socket.setSoTimeout" according to
http://java.sun.com/j2se/1.3/docs/guide/rmi/sunrmiproperties.html
...which is basically what the JCS socket factory does.
There's no jdk parameter to configure RMI "connection" timeouts as opposed to
just "read" timeouts as far as I can see for any of JDK 3, 4, 5 or 6.
...Basically this JDK4 method is needed to do that (i.e. programmatically only):
http://java.sun.com/j2se/1.4.2/docs/api/java/net/Socket.html#connect(java.net.SocketAddress,%20int)
It looks like the *intention* of the existing code was to configure socket
timeouts in general however? i.e. read AND connection timeouts?
> RemoteCache & RemoteCacheServerFactory setting RMISocketFactory
> ---------------------------------------------------------------
>
> Key: JCS-41
> URL: https://issues.apache.org/jira/browse/JCS-41
> Project: JCS
> Issue Type: Improvement
> Components: RMI Remote Cache
> Affects Versions: jcs-1.3, jcs-1.4-dev
> Environment: All
> Reporter: Niall Gallagher
> Assignee: Aaron Smuts
> Original Estimate: 1h
> Remaining Estimate: 1h
>
> Classes...
> org.apache.jcs.auxiliary.remote.RemoteCache
> and
> org.apache.jcs.auxiliary.remote.server.RemoteCacheServerFactory
> .. both try to set a timeout on RMI connections between the remote cache
> server and client machines using the following code to install a
> timeout-enabled socket factory which the RMI subsystem subsequently uses...
> RMISocketFactory.setSocketFactory( new RMISocketFactory() {
> public Socket createSocket( String host, int port ) throws
> IOException {
> Socket socket = new Socket( host, port );
> socket.setSoTimeout( DEFAULT_RMI_SOCKET_FACTORY_TIMEOUT_MS );
> socket.setSoLinger( false, 0 );
> return socket;
> }
> public ServerSocket createServerSocket( int port ) throws
> IOException {
> return new ServerSocket( port );
> }
> });
> The socket factory code above applies a "read timeout" to RMI sockets such
> that if a connection is already established and subsequently stalls or a
> machine goes offline, the timeout will break the connection as intended. The
> code does not apply a "connect timeout" however, which means that if an
> attempt is made to establish a new connection to a machine which is offline,
> the socket connection attempt will stall for an infinite amount of time (such
> is the default connect timeout), and therefore the thread opening the
> connection will stall permanently in the JVM.
> This is not a bug in JCS code, it was a limitation in JDK3 in that you could
> not AFAIK set a connection timeout on a socket.
> As of JDK4, there is a socket.connect(address, timeout) method, so this issue
> can be fixed.
> Here's the required replacement code:
> RMISocketFactory.setSocketFactory( new RMISocketFactory() {
> public Socket createSocket( String host, int port ) throws
> IOException {
> Socket socket = new Socket();
> socket.setSoTimeout(timeoutMillis);
> socket.setSoLinger( false, 0 );
> socket.connect(new InetSocketAddress(host, port),
> timeoutMillis);
> return socket;
> }
> public ServerSocket createServerSocket( int port ) throws
> IOException {
> return new ServerSocket( port );
> }
> });
> This was an issue for us recently. We fixed it by installing the
> RMISocketFactory above in the JVM before initializing JCS. We have tested and
> confirmed that this code works well with JCS, it times out reads same as
> before and it now times out new connection attempts too.
> How about including this in the next version of JCS?
> By the way I read some JCS mailing list archives from last time socket
> timeouts were discussed. Not sure if this will be helpful to anyone... but we
> found that if an RMI client and server were running on the same subnet,
> timeouts were not required and each machine detected that the other was
> offline immediately. Cross-subnet through our router however, timeouts became
> important as attempts to connect to an offline machine resulted in JCS
> threads hanging whilst trying to connect.
> We are not sure, but we suspect that this is related to our firewall blocking
> required ICMP "host not reachable" packets between subnets, causing different
> behaviour depending on the network setup. The replacement code above allows
> our machines in both subnets to recover when a machine is offline, previously
> they just stalled.
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