IT45685: INTEGRATION SERVERS RUNNING TCP FLOWS MAY RESULT IN DEADLOCK SITUATION DUE TO APAR IT44579 CHANGES.

APAR status

• Closed as program error.

Error description

• The integration servers running TCP flows might become
  unresponsive because of deadlock. A javacore collected at the
  time of issue shows following callstack with deadlock situation.
  
  1st thread:
  "Blocked on:
  com/ibm/broker/tcpip/ClientReadyForReadState@0x00000000F0489B88
  Owned by: "Thread-34" (J9VMThread:0x0000000002FE8200,
  java/lang/Thread:0x00000000F03D50C0)
      Heap bytes allocated since last GC cycle=2691760 (0x2912B0)
     Java callstack:
       at com/ibm/broker/tcpip/ReadyForReadState.remove(ReadyForR
  eadState.java:251(CompiledCode))
         (entered lock:
  com/ibm/broker/tcpip/ClientReadyForReadState@0x00000000F0489B88,
  entry count: 1)
       at com/ibm/broker/tcpip/Connection.waitForData(Connection.
  java:1995(CompiledCode))
         (entered lock: java/lang/Object@0x00000000F04E3B60, entry
  count: 1)"
  
  2nd thread:
  "Blocked on: java/lang/Object@0x00000000F04E3B60 Owned by:
  "Thread-32" (J9VMThread:0x0000000002FBB200,
  java/lang/Thread:0x00000000F03D4FC0)
      Heap bytes allocated since last GC cycle=12288 (0x3000)
     Java callstack:
       at com/ibm/broker/tcpip/Connection.setReadReadyState(Conne
  ction.java:1892(CompiledCode))
         (entered lock:
  com/ibm/broker/tcpip/ClientReadyForReadState@0x00000000F0489B88,
  entry count: 2)"
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  <span style="background-color:rgb(255, 255, 255)">All users of
  IBM App Connect Enterprise V12.0.11.0 using the TCPIP
  nodes.</span>
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  Multiple instances of concurrently running TCPIP flows may
  encounter deadlock situations, causing integration servers to
  become unresponsive.
  
  The Java core captured will show the deadlock situation for two
  threads with following call stack at the top.
  
  Thread-1 stack:
  
  3XMTHREADBLOCK   Blocked on:
  com/ibm/broker/tcpip/ClientReadyForReadState@0x00000000F0489B88
  Owned by: "Thread-34" (J9VMThread:0x0000000002FE8200,
  java/lang/Thread:0x00000000F03D50C0)
  3XMHEAPALLOC       Heap bytes allocated since last GC
  cycle=2691760 (0x2912B0)
  3XMTHREADINFO3      Java callstack:
  4XESTACKTRACE        at
  com/ibm/broker/tcpip/ReadyForReadState.remove(ReadyForReadState.
  java:251(Compiled Code))
  5XESTACKTRACE          (entered lock:
  com/ibm/broker/tcpip/ClientReadyForReadState@0x00000000F0489B88,
   entry count: 1)
  4XESTACKTRACE        at
  com/ibm/broker/tcpip/Connection.waitForData(Connection.java:1995
  (Compiled Code))
  5XESTACKTRACE          (entered lock:
  java/lang/Object@0x00000000F04E3B60, entry count: 1)
  4XESTACKTRACE        at
  com/ibm/broker/tcpip/ReadyForReadState.getConnection(ReadyForRea
  dState.java:160(Compiled Code))
  
  Thread-2 stack:
  3XMTHREADBLOCK   Blocked on: java/lang/Object@0x00000000F04E3B60
  Owned by: "Thread-32" (J9VMThread:0x0000000002FBB200,
  java/lang/Thread:0x00000000F03D4FC0)
  3XMHEAPALLOC       Heap bytes allocated since last GC
  cycle=12288 (0x3000)
  3XMTHREADINFO3      Java callstack:
  4XESTACKTRACE        at
  com/ibm/broker/tcpip/Connection.setReadReadyState(Connection.jav
  a:1892(Compiled Code))
  5XESTACKTRACE          (entered lock:
  com/ibm/broker/tcpip/ClientReadyForReadState@0x00000000F0489B88,
   entry count: 2)
  4XESTACKTRACE        at
  com/ibm/broker/tcpip/WaitingForReadDataState.getReadyConnections
  (WaitingForReadDataState.java:225(Compiled Code))
  5XESTACKTRACE          (entered lock:
  java/lang/Object@0x00000000F0489BB0, entry count: 1)
  5XESTACKTRACE          (entered lock:
  com/ibm/broker/tcpip/ClientReadyForReadState@0x00000000F0489B88,
   entry count: 1)
  

Problem conclusion

• The product no more causes deadlock situation with TCPIP message
  flows.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v12.0      12.0.12.0
  
  The latest available maintenance can be obtained from:
  http://www-01.ibm.com/support/docview.wss?rs=849&uid=swg27006041
  
  If the maintenance level is not yet available,information on
  its planned availability can be found on:
  http://www-1.ibm.com/support/docview.wss?rs=849&uid=swg27006308
  ---------------------------------------------------------------
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  APP CONNECT ENT

• Fixed component ID

  5724J0560

Applicable component levels