We have a multi-threading application using third party tool "CPLEX"
which had been running for quite number of years without any problem.
Lately, we have encountered with jobs hanging. We noticed this problem
after upgrading from HP-UX 11.0 to 11.11. There was no code change
when upgrading to HP-UX 11.11 (only compilation in the new
environment).
The following is from the stack dump. As you can see thread 1 is
waiting for thread 2 to finish before joining. However, thread 2
never finishes. This problem does not always happen from run to run,
but on the average happens in 1 out of 10 runs. It occurs more often
when the machine is heavily used with multiple jobs running at the
same time and each job uses 2 or more threads.
Any idea what's happening?

uname -a:
HP-UX carlsbad B.11.11 U 9000/800 unknown unknown HP-UX

thread 2 where
#0 0x40000000003618a4 in autoorder_par ()
#1 0x40000000001a76a4 in posforkstub ()
#2 0xc00000000006c250 in __pthread_body () from
/usr/lib/pa20_64/libpthread.1
#3 0xc000000000076b0c in __pthread_start () from
/usr/lib/pa20_64/libpthread.1

thread 1 where
#0 0xc000000000076dbc in ___lwp_wait_sys () from
/usr/lib/pa20_64/libpthread.1
warning: reading `r3' register: No data
#1 0xc000000000076870 in _lwp_wait () from
/usr/lib/pa20_64/libpthread.1
warning: reading `r3' register: No data
#2 0xc00000000006d778 in __vp_join () from
/usr/lib/pa20_64/libpthread.1
warning: reading `r3' register: No data
#3 0xc00000000006c368 in pthread_join () from
/usr/lib/pa20_64/libpthread.1
#4 0x40000000001a761c in CPXPparfork ()
#5 0x40000000003612c8 in BAR_neword ()
#6 0x4000000000360054 in CPXPbar_doorder ()
#7 0x4000000000353c34 in CPXPbar_main ()
#8 0x400000000026714c in CPXPcpxbar ()
#9 0x4000000000266d68 in baropt ()
#10 0x40000000002651e0 in CPXPShybbaropt ()
#11 0x400000000018408c in CPXhybbaropt ()
#12 0x40000000001ea6d4 in bsolvelp ()
#13 0x40000000001e9ff8 in CPXPsolvelp ()
#14 0x40000000001aa490 in mipsetup ()
#15 0x40000000001a8b94 in mipopt ()
#16 0x40000000001a8368 in CPXPSmipopt ()
#17 0x40000000001841bc in CPXmipopt ()
#18 0x40000000000c7608 in CPXOptimizer::Optimize
(this=0x80000001000395a0, optimizati
#19 0x4000000000087390 in FAMOptimizerBase::SolveMIP
(this=0x80000001000395a0, varGro
#20 0x400000000008bffc in FAMOptimizerBase::BranchAndBound
(this=0x80000001000395a0,
#21 0x400000000008b218 in FAMOptimizerBase::BranchAndBound
(this=0x80000001000395a0)
#22 0x40000000000a9970 in SolveProblem
(optimizerObj=0x80000001000395a0, isLegFamForS
AFfamDir=0x800003ffe80f1b38 "/export/local_fs/riad",
scenario=0x800003ffe80f1a30
#23 0x40000000000a7c14 in main (argc=3, argv=0x800003ffe80f1380) at
FAM_OptDriver.C:1



Nurman