Program received signal SIG34

I received the message below when I debug my program with "gdb", how does it happen?

Program received signal SIG34, Real-time event 34.
[Switching to Thread -1218925648 (LWP 29942)]
0xb7680de2 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib/tls/libpthread.so.0
(gdb) bt
#0 0xb7680de2 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib/tls/libpthread.so.0
#1 0xb7769ef4 in pthread_cond_timedwait () from /lib/tls/libc.so.6
#2 0xb7e8fde4 in timedWaitImpl<IceUtil::Mutex> (this=0x8ad4fc4, mutex=@0x8ad4ff4, timeout=@0x8ad5014) at Cond.h:224
#3 0xb7e8edc2 in IceUtil::Monitor<IceUtil::Mutex>::timedWait (this=0x8ad4fc4, timeout=@0x8ad5014) at Monitor.h:180
#4 0xb7e94e45 in IceInternal::ConnectionMonitor::run (this=0x8ad4fa0) at ConnectionMonitor.cpp:78
#5 0xb7d41808 in startHook (arg=0x8ad4fa0) at Thread.cpp:357
#6 0xb767eced in start_thread () from /lib/tls/libpthread.so.0
#7 0xb775cdee in clone () from /lib/tls/libc.so.6