Name: mf23781 Date: 04/14/99


This problem had been previously addressed by SUN bugid 4137568
and fixed in JDK 1.2. We would like this to be fixed in JDK1.1.7

Description of the problem:
===========================


I have 2 remote objects (call them R1 and R2) each of which extend UnicastRemoteObject and each
of which implement an interface that extends Remote. R1 is started and binds itself in the registry.
R2 is started, looks up R1 in the registry, and sends a reference to itself to R1. R1 stores the reference
to R2, but does not try to contact R2. Once R2 has successfully sent a reference of itself to R1, I do a
CTRL-Z on R2 and leave R2 in that suspended state. Shortly after I do that CTRL-Z, new remote objects
(of the same type as R2) are no longer able to contact R1. I don't receive any exceptions, my program
that is trying to contact R1 simply hangs.

Comments by Peter Jones - JavaSoft East <###@###.###>
====================================================================

Date: Thu, 4 Mar 1999 09:44:11 -0500
Reply-To: Peter Jones - JavaSoft East <###@###.###>
From: Peter Jones - JavaSoft East <###@###.###>
Subject: Re: Hang condition when an RMI object is suspended
======================================================================

The following thread dump from 1.1.7B java shows
the problem. The first TestObject process is suspended.
10 minutes later the thread dump is obtained from the RMI server process
"HelloServer" after a 2nd TestObject has handed a copy of itself
to the HelloServer and the HelloServer is trying to ack the copy by
making a call to DGCClient.referenced() (TCP Accept-6 thread)
but hangs there since the lock is already acquired by LeaseRenewer thread
which is hanging because the first TestObject process is not responding.

Full thread dump:
    "TCP Accept-8" (TID:0xee305e98, sys_thread_t:0xef0d1db8, state:CW) prio=5
java.net.PlainSocketImpl.accept(PlainSocketImpl.java:379)
java.net.ServerSocket.implAccept(ServerSocket.java:198)
java.net.ServerSocket.accept(ServerSocket.java:181)
sun.rmi.transport.proxy.HttpAwareServerSocket.accept(HttpAwareServerSocket.java:70)
sun.rmi.transport.tcp.TCPTransport.run(TCPTransport.java:358)
java.lang.Thread.run(Thread.java)
    "TCP Accept-6" (TID:0xee305400, sys_thread_t:0xef101db8, state:MW) prio=5
sun.rmi.transport.DGCClient.referenced(DGCClient.java:118)
sun.rmi.transport.ConnectionInputStream.registerRefs(ConnectionInputStream.java:101)
sun.rmi.transport.StreamRemoteCall.releaseInputStream(StreamRemoteCall.java:137)
HelloImpl_Skel.dispatch(HelloImpl_Skel.java:37)
sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:164)
sun.rmi.transport.Transport.serviceCall(Transport.java:154)
sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:600)
sun.rmi.transport.tcp.TCPTransport.run(TCPTransport.java:506)
java.lang.Thread.run(Thread.java)
    "Cleaner" (TID:0xee305250, sys_thread_t:0xef131db8, state:CW) prio=5
sun.rmi.transport.DGCClient.run(DGCClient.java:621)
java.lang.Thread.run(Thread.java)
    "LeaseRenewer" (TID:0xee305168, sys_thread_t:0xef161db8, state:CW) prio=5
java.net.SocketInputStream.read(SocketInputStream.java:84)
java.io.BufferedInputStream.fill(BufferedInputStream.java)
java.io.BufferedInputStream.read(BufferedInputStream.java)
java.io.DataInputStream.readByte(DataInputStream.java)
sun.rmi.transport.tcp.TCPChannel.newConnection(TCPChannel.java:140)
sun.rmi.server.UnicastRef.newCall(UnicastRef.java:67)
sun.rmi.transport.DGCImpl_Stub.dirty(DGCImpl_Stub.java:58)
sun.rmi.transport.DGCClient.renewLeases(DGCClient.java:773)
sun.rmi.transport.DGCClient.doRenewal(DGCClient.java:705)
sun.rmi.transport.DGCClient$LeaseRenewer.run(DGCClient.java:936)
java.lang.Thread.run(Thread.java)
    "LeaseChecker" (TID:0xee300290, sys_thread_t:0xef191db8, state:CW) prio=5
sun.rmi.transport.DGCImpl$LeaseChecker.run(DGCImpl.java:303)
java.lang.Thread.run(Thread.java)
    "TCP Accept-2" (TID:0xee305ec8, sys_thread_t:0xef1c1db8, state:CW) prio=5
java.net.SocketInputStream.read(SocketInputStream.java:84)
java.io.BufferedInputStream.fill(BufferedInputStream.java)
java.io.BufferedInputStream.read(BufferedInputStream.java)
java.io.BufferedInputStream.fill(BufferedInputStream.java)
java.io.BufferedInputStream.read(BufferedInputStream.java)
java.io.DataInputStream.readByte(DataInputStream.java)
sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:589)
sun.rmi.transport.tcp.TCPTransport.run(TCPTransport.java:506)
java.lang.Thread.run(Thread.java)
    "KeepAlive" (TID:0xee304e40, sys_thread_t:0xef241db8, state:CW) prio=5
sun.rmi.transport.KeepAlive.run(ObjectTable.java:182)
java.lang.Thread.run(Thread.java)
    "Reaper" (TID:0xee304ea0, sys_thread_t:0xef271db8, state:CW) prio=5
sun.rmi.transport.Reaper.run(ObjectTable.java:199)
java.lang.Thread.run(Thread.java)
    "Finalizer thread" (TID:0xee300210, sys_thread_t:0xef341db8, state:CW) prio=1
    "Async Garbage Collector" (TID:0xee300258, sys_thread_t:0xef371db8, state:CW) prio=1
    "Idle thread" (TID:0xee3002a0, sys_thread_t:0xef471db8, state:R) prio=0 *current thread*
    "Clock" (TID:0xee300088, sys_thread_t:0xef561db8, state:CW) prio=12
    "main" (TID:0xee3000b0, sys_thread_t:0x2eaf8, state:CW) prio=5
Monitor Cache Dump:
    java.net.PlainSocketImpl@EE304DB0/EE3587C8: owner "TCP Accept-8" (0xef0d1db8, 1 entry)
    <unknown key> (0xef241db8): <unowned>
Waiting to be notified:
"KeepAlive" (0xef241db8)
    java.io.BufferedInputStream@EE3059F8/EE35BE88: owner "LeaseRenewer" (0xef161db8, 1 entry)
    java.io.BufferedInputStream@EE305DD0/EE358728: owner "TCP Accept-2" (0xef1c1db8, 1 entry)
    <unknown key> (0xef191db8): <unowned>
Waiting to be notified:
"LeaseChecker" (0xef191db8)
    <unknown key> (0xef371db8): <unowned>
Waiting to be notified:
"Async Garbage Collector" (0xef371db8)
    <unknown key> (0xef271db8): <unowned>
Waiting to be notified:
"Reaper" (0xef271db8)
    java.lang.Object@EE305030/EE358E88: owner "LeaseRenewer" (0xef161db8, 1 entry)
Waiting to enter:
"TCP Accept-6" (0xef101db8)
    java.util.Vector@EE305068/EE359040: <unowned>
Waiting to be notified:
"Cleaner" (0xef131db8)
    java.io.BufferedInputStream@EE303628/EE358A68: owner "TCP Accept-2" (0xef1c1db8, 1 entry)
Registered Monitor Dump:
    Thread queue lock: <unowned>
Waiting to be notified:
"main" (0x2eaf8)
    Name and type hash table lock: <unowned>
    String intern lock: <unowned>
    JNI pinning lock: <unowned>
    JNI global reference lock: <unowned>
    BinClass lock: <unowned>
    Class loading lock: <unowned>
    Java stack lock: <unowned>
    Code rewrite lock: <unowned>
    Heap lock: <unowned>
    Has finalization queue lock: <unowned>
    Finalize me queue lock: <unowned>
Waiting to be notified:
"Finalizer thread" (0xef341db8)
    Dynamic loading lock: <unowned>
    Monitor IO lock: <unowned>
    Child death monitor: <unowned>
    Event monitor: <unowned>
    I/O monitor: <unowned>
    Alarm monitor: <unowned>
Waiting to be notified:
"Clock" (0xef561db8)
    Sbrk lock: <unowned>
    Monitor registry: owner "Idle thread" (0xef471db8, 1 entry)
Thread Alarm Q:
    sys_thread_t 0xef371db8 [Timeout in 923 ms]
    sys_thread_t 0xef271db8 [Timeout in 2794 ms]
    sys_thread_t 0xef131db8 [Timeout in 49594 ms]
    sys_thread_t 0xef191db8 [Timeout in 199197 ms]
    sys_thread_t 0xef241db8 [Timeout in 2146481018 ms]


patrick.ong@Eng 1999-05-10