System crash when running parallel unzipping in MainEvent.cxx

I am trying to run parallel unzipping in MainEvent.cxx.

I created a root file by:
./eventexe 4000 6 99 1 1000

and when I tried to read it with parallel unzipping by:
./eventexe 4000 6 99 21 1000

Both Ubuntu and Scientific Linux crashed.

I attach system logs as follows.
Ubuntu:
======================================================
The lines below might hint at the cause of the crash.
You may get help by asking at the ROOT forum http://root.cern.ch/forum.
Only if you are really convinced it is a bug in ROOT then please submit a
report at http://root.cern.ch/bugs. Please post the ENTIRE stack trace
from above as an attachment in addition to anything else
that might help us fixing this issue.
===========================================================
#6 __memcpy_sse2_unaligned () at ../sysdeps/x86_64/multiarch/memcpy-sse2-unaligned.S:37
#7 0x00007fca70024161 in memcpy (__len=<optimized out>, __src=0x2918970, __dest=<optimized out>) at /usr/include/x86_64-linux-gnu/bits/string3.h:53
#8 TTreeCacheUnzip::UnzipBuffer (this=this
entry=0x28ebd00, dest=dest
entry=0x7ffc67177170, src=0x2918970 "") at /home/zhe/root/tree/tree/src/TTreeCacheUnzip.cxx:984
#9 0x00007fca700245da in TTreeCacheUnzip::GetUnzipBuffer (this=0x28ebd00, buf=0x7ffc67177170, pos=30048627, len=107, free=0x7ffc6717716c) at /home/zhe/root/tree/tree/src/TTreeCacheUnzip.cxx:908
#10 0x00007fca7006bbe7 in TBasket::ReadBasketBuffers (this=this
entry=0x2917fe0, pos=30048627, len=107, file=file
entry=0x13cf440) at /home/zhe/root/tree/tree/src/TBasket.cxx:451
#11 0x00007fca70088ad6 in TBranch::GetBasket (this=this
entry=0x29a6380, basketnumber=0) at /home/zhe/root/tree/tree/src/TBranch.cxx:1132
#12 0x00007fca700890e3 in TBranch::GetEntry (this=this
entry=0x29a6380, entry=entry
entry=0, getall=getall
entry=0) at /home/zhe/root/tree/tree/src/TBranch.cxx:1258
#13 0x00007fca700583f0 in TBranchElement::GetEntry (this=0x29a6380, entry=0, getall=0) at /home/zhe/root/tree/tree/src/TBranchElement.cxx:2325
#14 0x00007fca70058395 in TBranchElement::GetEntry (this=0x29a5eb0, entry=0, getall=0) at /home/zhe/root/tree/tree/src/TBranchElement.cxx:2308
#15 0x00007fca70058395 in TBranchElement::GetEntry (this=0x2998070, entry=0, getall=0) at /home/zhe/root/tree/tree/src/TBranchElement.cxx:2308
#16 0x00007fca7003ca30 in TTree::<lambda()>::operator() (__closure=<synthetic pointer>) at /home/zhe/root/tree/tree/src/TTree.cxx:5231
#17 TTree::GetEntry (this=0x266c7a0, entry=0, getall=0) at /home/zhe/root/tree/tree/src/TTree.cxx:5299
#18 0x0000000000402119 in main (argc=<optimized out>, argv=<optimized out>) at /home/zhe/root/test/MainEvent.cxx:177
===========================================================

Scientific Linux
===========================================================

• • • Break *** segmentation violation

===========================================================
There was a crash.
This is the entire stack trace of all threads:
===========================================================

Thread 3 (Thread 0x7f2d1f3c2700 (LWP 30843)):
#0 0x0000003fa220ba5e in pthread_cond_timedwait

GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00007f2d35e91d31 in TPosixCondition::TimedWait (this=<optimized out>, secs=<optimized out>, nanoSecs=<optimized out>) at /home/bockelman/zhan0915/root/core/thread/src/TPosixCondition.cxx:78
#2 0x00007f2d35e8dc01 in TCondition::TimedWait (this=this
entry=0x1df8b20, secs=<optimized out>, nanoSec=<optimized out>) at /home/bockelman/zhan0915/root/core/thread/src/TCondition.cxx:101
#3 0x00007f2d35e8dcd3 in TCondition::TimedWaitRelative (this=0x1df8b20, ms=ms
entry=2000) at /home/bockelman/zhan0915/root/core/thread/src/TCondition.cxx:129
#4 0x00007f2d37572341 in TTreeCacheUnzip::WaitUnzipStartSignal (this=this
entry=0x1dd1670) at /home/bockelman/zhan0915/root/tree/tree/src/TTreeCacheUnzip.cxx:416
#5 0x00007f2d3757401b in TTreeCacheUnzip::UnzipLoop (arg=0x1dfd190) at /home/bockelman/zhan0915/root/tree/tree/src/TTreeCacheUnzip.cxx:575
#6 0x00007f2d35e90471 in TThread::Function (ptr=0x1dfd1b0) at /home/bockelman/zhan0915/root/core/thread/src/TThread.cxx:812
#7 0x0000003fa2207aa1 in start_thread () from /lib64/libpthread.so.0
#8 0x0000003fa1ee893d in clone () from /lib64/libc.so.6

Thread 2 (Thread 0x7f2d1e9c1700 (LWP 30844)):
#0 0x0000003fa220ba5e in pthread_cond_timedwait

GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00007f2d35e91d31 in TPosixCondition::TimedWait (this=<optimized out>, secs=<optimized out>, nanoSecs=<optimized out>) at /home/bockelman/zhan0915/root/core/thread/src/TPosixCondition.cxx:78
#2 0x00007f2d35e8dc01 in TCondition::TimedWait (this=this
entry=0x1df8b20, secs=<optimized out>, nanoSec=<optimized out>) at /home/bockelman/zhan0915/root/core/thread/src/TCondition.cxx:101
#3 0x00007f2d35e8dcd3 in TCondition::TimedWaitRelative (this=0x1df8b20, ms=ms
entry=2000) at /home/bockelman/zhan0915/root/core/thread/src/TCondition.cxx:129
#4 0x00007f2d37572341 in TTreeCacheUnzip::WaitUnzipStartSignal (this=this
entry=0x1dd1670) at /home/bockelman/zhan0915/root/tree/tree/src/TTreeCacheUnzip.cxx:416
#5 0x00007f2d3757401b in TTreeCacheUnzip::UnzipLoop (arg=0x1dfd930) at /home/bockelman/zhan0915/root/tree/tree/src/TTreeCacheUnzip.cxx:575
#6 0x00007f2d35e90471 in TThread::Function (ptr=0x1dfd950) at /home/bockelman/zhan0915/root/core/thread/src/TThread.cxx:812
#7 0x0000003fa2207aa1 in start_thread () from /lib64/libpthread.so.0
#8 0x0000003fa1ee893d in clone () from /lib64/libc.so.6

Thread 1 (Thread 0x7f2d3560eb60 (LWP 30765)):
#0 0x0000003fa1eac69d in waitpid () from /lib64/libc.so.6
#1 0x0000003fa1e3e609 in do_system () from /lib64/libc.so.6
#2 0x0000003fa1e3e940 in system () from /lib64/libc.so.6
#3 0x00007f2d35b33ecf in TUnixSystem::StackTrace (this=0x8b0900) at /home/bockelman/zhan0915/root/core/unix/src/TUnixSystem.cxx:2403
#4 0x00007f2d35b367ac in TUnixSystem::DispatchSignals (this=0x8b0900, sig=kSigSegmentationViolation) at /home/bockelman/zhan0915/root/core/unix/src/TUnixSystem.cxx:3661
#5 <signal handler called>
#6 0x00007f2d37515630 in TBasket::ReadBasketBuffers (this=this
entry=0x1e000d0, pos=259499424219136, len=107, file=file
entry=0x926560) at /home/bockelman/zhan0915/root/tree/tree/src/TBasket.cxx:518
#7 0x00007f2d3751a0ca in TBranch::GetBasket (this=this
entry=0x1f3cf20, basketnumber=0) at /home/bockelman/zhan0915/root/tree/tree/src/TBranch.cxx:1132
#8 0x00007f2d3751a586 in TBranch::GetEntry (this=this
entry=0x1f3cf20, entry=entry
entry=2, getall=getall
entry=0) at /home/bockelman/zhan0915/root/tree/tree/src/TBranch.cxx:1258
#9 0x00007f2d37531c08 in TBranchElement::GetEntry (this=0x1f3cf20, entry=2, getall=0) at /home/bockelman/zhan0915/root/tree/tree/src/TBranchElement.cxx:2325
#10 0x00007f2d37531bb8 in TBranchElement::GetEntry (this=0x1f3cad0, entry=2, getall=0) at /home/bockelman/zhan0915/root/tree/tree/src/TBranchElement.cxx:2308
#11 0x00007f2d37531bb8 in TBranchElement::GetEntry (this=0x1f2ec10, entry=2, getall=0) at /home/bockelman/zhan0915/root/tree/tree/src/TBranchElement.cxx:2308
#12 0x00007f2d37567da1 in operator() (__closure=<synthetic pointer>) at /home/bockelman/zhan0915/root/tree/tree/src/TTree.cxx:5231
#13 TTree::GetEntry (this=0x1b58af0, entry=2, getall=0) at /home/bockelman/zhan0915/root/tree/tree/src/TTree.cxx:5298
#14 0x0000000000401eac in main (argc=<optimized out>, argv=<optimized out>) at /home/bockelman/zhan0915/root/test/MainEvent.cxx:177
===========================================================

The lines below might hint at the cause of the crash.
You may get help by asking at the ROOT forum http://root.cern.ch/forum.
Only if you are really convinced it is a bug in ROOT then please submit a
report at http://root.cern.ch/bugs. Please post the ENTIRE stack trace
from above as an attachment in addition to anything else
that might help us fixing this issue.
===========================================================
#6 0x00007f2d37515630 in TBasket::ReadBasketBuffers (this=this
entry=0x1e000d0, pos=259499424219136, len=107, file=file
entry=0x926560) at /home/bockelman/zhan0915/root/tree/tree/src/TBasket.cxx:518
#7 0x00007f2d3751a0ca in TBranch::GetBasket (this=this
entry=0x1f3cf20, basketnumber=0) at /home/bockelman/zhan0915/root/tree/tree/src/TBranch.cxx:1132
#8 0x00007f2d3751a586 in TBranch::GetEntry (this=this
entry=0x1f3cf20, entry=entry
entry=2, getall=getall
entry=0) at /home/bockelman/zhan0915/root/tree/tree/src/TBranch.cxx:1258
#9 0x00007f2d37531c08 in TBranchElement::GetEntry (this=0x1f3cf20, entry=2, getall=0) at /home/bockelman/zhan0915/root/tree/tree/src/TBranchElement.cxx:2325
#10 0x00007f2d37531bb8 in TBranchElement::GetEntry (this=0x1f3cad0, entry=2, getall=0) at /home/bockelman/zhan0915/root/tree/tree/src/TBranchElement.cxx:2308
#11 0x00007f2d37531bb8 in TBranchElement::GetEntry (this=0x1f2ec10, entry=2, getall=0) at /home/bockelman/zhan0915/root/tree/tree/src/TBranchElement.cxx:2308
#12 0x00007f2d37567da1 in operator() (__closure=<synthetic pointer>) at /home/bockelman/zhan0915/root/tree/tree/src/TTree.cxx:5231
#13 TTree::GetEntry (this=0x1b58af0, entry=2, getall=0) at /home/bockelman/zhan0915/root/tree/tree/src/TTree.cxx:5298
#14 0x0000000000401eac in main (argc=<optimized out>, argv=<optimized out>) at /home/bockelman/zhan0915/root/test/MainEvent.cxx:177
===========================================================