PK26039: ADJUSTMENTS MADE TO NETWORK CLOCK TIME CAUSING DUPLICATE UUID EVENTS WHEN EXECUTING THE CODE ON FAST PROCESSORS.

 Fixes are available

5.1.1.17: WebSphere Application Server V5.1.1 Cumulative Fix 17 for AIX
5.1.1.17: WebSphere Application Server V5.1.1 Cumulative Fix 17 for HP-UX
5.1.1.19: WebSphere Application Server V5.1.1 Cumulative Fix 19 for Linux
5.1.1.16: WebSphere Application Server V5.1.1 Cumulative Fix 16 for AIX
5.1.1.18: WebSphere Application Server V5.1.1 Cumulative Fix 18 for AIX
5.1.1.18: WebSphere Application Server V5.1.1 Cumulative Fix 18 for HP-UX
5.1.1.18: WebSphere Application Server V5.1.1 Cumulative Fix 18 for Solaris
5.1.1.18: WebSphere Application Server V5.1.1 Cumulative Fix 18 for Windows
5.1.1.18: WebSphere Application Server V5.1.1 Cumulative Fix 18 for Linux
5.1.1.17: WebSphere Application Server V5.1.1 Cumulative Fix 17 for Linux
5.1.1.17: WebSphere Application Server V5.1.1 Cumulative Fix 17 for Solaris
5.1.1.17: WebSphere Application Server V5.1.1 Cumulative Fix 17 for Windows
5.1.1.19: WebSphere Application Server V5.1.1 Cumulative Fix 19 for AIX
5.1.1.19: WebSphere Application Server V5.1.1 Cumulative Fix 19 for Windows
5.1.1.12: WebSphere Application Server V5.1.1 Cumulative Fix 12 for Windows
5.1.1.16: WebSphere Application Server V5.1.1 Cumulative Fix 16 for Solaris
5.1.1.16: WebSphere Application Server V5.1.1 Cumulative Fix 16 for Windows
5.1.1.14: WebSphere Application Server V5.1.1 Cumulative Fix 14 for Solaris
5.1.1.12: WebSphere Application Server V5.1.1 Cumulative Fix 12 for AIX
5.1.1.12: WebSphere Application Server V5.1.1 Cumulative Fix 12 for Linux
5.1.1.12: WebSphere Application Server V5.1.1 Cumulative Fix 12 for HP-UX
5.1.1.12: WebSphere Application Server V5.1.1 Cumulative Fix 12 for Solaris
5.1.1.13: WebSphere Application Server V5.1.1 Cumulative Fix 13 for AIX
5.1.1.13: WebSphere Application Server V5.1.1 Cumulative Fix 13 for Windows
5.1.1.13: WebSphere Application Server V5.1.1 Cumulative Fix 13 for HP-UX
5.1.1.15: WebSphere Application Server V5.1.1 Cumulative Fix 15 for Solaris
5.1.1.13: WebSphere Application Server V5.1.1 Cumulative Fix 13 for Solaris
5.1.1.13: WebSphere Application Server V5.1.1 Cumulative Fix 13 for Linux
5.1.1.14: WebSphere Application Server V5.1.1 Cumulative Fix 14 for AIX
5.1.1.14: WebSphere Application Server V5.1.1 Cumulative Fix 14 for Linux
5.1.1.14: WebSphere Application Server V5.1.1 Cumulative Fix 14 for Windows
5.1.1.15: WebSphere Application Server V5.1.1 Cumulative Fix 15 for Windows
5.1.1.14: WebSphere Application Server V5.1.1 Cumulative Fix 14 for HP-UX
5.1.1.15: WebSphere Application Server V5.1.1 Cumulative Fix 15 for AIX
5.1.1.15: WebSphere Application Server V5.1.1 Cumulative Fix 15 for HP-UX
5.1.1.16: WebSphere Application Server V5.1.1 Cumulative Fix 16 for HP-UX
5.1.1.16: WebSphere Application Server V5.1.1 Cumulative Fix 16 for Linux
5.1.1.15: WebSphere Application Server V5.1.1 Cumulative Fix 15 for Linux
5.1.1.19: WebSphere Application Server V5.1.1 Cumulative Fix 19 for HP-UX



APAR status
Closed as program error.

Error description
The following exceptions are received in the SystemOut.log over
and over

[1/3/06 14:00:20:451 EST] 19d7f6d CScopeRootImp E CSCP0007E: An
unexpected error occurred in method completeActivity in cl
ass CScopeRootImpl; the exception stack trace follows:
com.ibm.ws.javax.activity.NoActivityException
com.ibm.ws.activity.UserActivityImpl.completeWithStatus(UserActi
vityImpl
.java:2233)
com.ibm.ws.cscope.CScopeRootImpl.completeActivity(CScopeRootImpl
.java:14
5)
com.ibm.ws.cscope.CScopeRootImpl.afterCompletion(CScopeRootImpl.
java:358
)
com.ibm.ws.Transaction.JTA.RegisteredSyncs.distributeAfter(Regis
teredSyn
cs.java:195)
com.ibm.ws.Transaction.JTA.TransactionImpl.distributeAfter(Trans
actionIm
pl.java:2452)


On a network-scale, the different devices connected within the
network can and often do have a different perspective on what
the actual current time presently is. However, within
distributed systems this can cause a problem and therefore
there exists a protocol for networked UNIX computers to provide
some consensus of time and permits changes to local clocks on
those devices.  This infrastructure is implemented in UNIX via
the network time process (NTP) daemon. And, the occassion of
time going backwards represented the events of some corrections
for those local clocks where that clock sequence moved
backwards into the past - not by much, but by enough.

Thus, the problem develops because in constructing the type of
unique UUID being used for such global unique references, the
current timestamp is one of the primary constituents that forms
this unique value. This establishes the time dependency.
Furthermore, the rate at which the JVM may process the code
that seeks the creation of new unique references was just fast
enough under Server JIT optimisation for the problem of
duplicate timestamps to become an issue. Thus, the risk of the
problem of obtaining a duplicate timestamp is related to
the average size of the correction interval negotiated by the
NTP time correction daemon processes.
Local fix
N/A
Problem summary
****************************************************************
* USERS AFFECTED: All WebSphere Application Server Activity    *
*                 Service Users                                *
****************************************************************
* PROBLEM DESCRIPTION: Adjustments made to network clock time  *
*                      allowed the generation of duplicate     *
*                      Unique User ID's.  This caused some     *
*                      activity sessions to be created with    *
*                      the same identifiers,  spawning a       *
*                      variety of problems related to the      *
*                      management of activity sessions. These  *
*                      are usually accompanied by error msg    *
*                      CSCP0007E, caused by the occurrence of  *
*                      an unexpected error in the activity     *
*                      session.                                *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
On a network-scale, the different devices connected within the
network can and often do have a different perspective on what
the actual current time presently is. However, within
distributed systems this can cause a problem and therefore
there exists a protocol for networked UNIX computers to provide
some consensus of time and permits changes to local clocks on
those devices.  This infrastructure is implemented in UNIX via
the network time process (NTP) daemon. And, the occassion of
time going backwards represented the events of some corrections
for those local clocks where that clock sequence moved
backwards into the past - not by much, but by enough.

Thus, the problem develops because in constructing the type of
unique UUID being used for such global unique references, the
current timestamp is one of the primary constituents that forms
this unique value. This establishes the time dependency.
Furthermore, the rate at which the JVM may process the code
that seeks the creation of new unique references was just fast
enough under Server JIT optimisation for the problem of
duplicate timestamps to become an issue. Thus, the risk of the
problem of obtaining a duplicate timestamp is related to
the average size of the correction interval negotiated by the
NTP time correction daemon processes.
Problem conclusion
The UUID class was modified to detect when a value is returned
for a time that is in the past, compared to the previously
returned valid time.  If this happens, the class waits until
the network clock returns a time value which is later than the
last previously returned valid time.

If the network clock returns a time from the past (when
compared to a previously returned time), it will output a
message to the system log, indicating that the class will wait
until a new valid time is returned.

The fix for this APAR is currently targeted for inclusion in
fixpacks 5.1.1.12, 6.0.2.17 and 6.1.0.4
Please refer to the Recommended Updates page for delivery
information:

http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
Temporary fix Comments
APAR information
APAR number PK26039
Reported component name WEBSPHERE BASE
Reported component ID 5630A3600
Reported release 10W
Status CLOSED PER
PE NoPE
HIPER NoHIPER
Special Attention NoSpecatt
Submitted date 2006-06-06
Closed date 2006-08-24
Last modified date 2006-09-13

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:

Modules/Macros
UUID          

Publications Referenced

Fix information
Fixed component name WEBSPHERE BASE
Fixed component ID 5630A3600

Applicable component levels
R003 PSN    UP
R00A PSN    UP
R00H PSN    UP
R00I PSN    UP
R00P PSN    UP
R00S PSN    UP
R00W PSN    UP
R103 PSY    UP
R10A PSY    UP
R10H PSY    UP
R10I PSY    UP
R10P PSY    UP
R10S PSY    UP
R10W PSY    UP


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > General
Operating system(s):
Software version: 10W
Software edition:
Reference #: PK26039
IBM Group: Software Group
Modified date: Sep 13, 2006