hung node.js process

(gdb) thread apply all bt

Thread 5 (Thread 0x7f36b0d64700 (LWP 7760)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:211
#1  0x00000000004e22cc in etp_proc (thr_arg=<value optimized out>) at ../deps/libeio/eio.c:1490
#2  0x00007f36d557f9ca in start_thread (arg=<value optimized out>) at pthread_create.c:300
#3  0x00007f36d52dc70d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#4  0x0000000000000000 in ?? ()

Thread 4 (Thread 0x7f36af472700 (LWP 7766)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:211
#1  0x00000000004e22cc in etp_proc (thr_arg=<value optimized out>) at ../deps/libeio/eio.c:1490
#2  0x00007f36d557f9ca in start_thread (arg=<value optimized out>) at pthread_create.c:300
#3  0x00007f36d52dc70d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#4  0x0000000000000000 in ?? ()

Thread 3 (Thread 0x7f36af461700 (LWP 7767)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:211
#1  0x00000000004e22cc in etp_proc (thr_arg=<value optimized out>) at ../deps/libeio/eio.c:1490
#2  0x00007f36d557f9ca in start_thread (arg=<value optimized out>) at pthread_create.c:300
#3  0x00007f36d52dc70d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#4  0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7f36af390700 (LWP 7774)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:211
#1  0x00000000004e22cc in etp_proc (thr_arg=<value optimized out>) at ../deps/libeio/eio.c:1490
#2  0x00007f36d557f9ca in start_thread (arg=<value optimized out>) at pthread_create.c:300
#3  0x00007f36d52dc70d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#4  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f36d6b3f720 (LWP 7759)):
#0  0x00007f36d52dcd03 in epoll_wait () at ../sysdeps/unix/syscall-template.S:82
#1  0x00000000004eaa95 in epoll_poll (timeout=<value optimized out>) at ../deps/libev/ev_epoll.c:127
#2  0x00000000004ebb2b in ev_loop (flags=<value optimized out>) at ../deps/libev/ev.c:2337
#3  0x00000000004bcb47 in Loop (args=<value optimized out>) at ../src/node.cc:1025
#4  0x0000000000518516 in v8::internal::Builtin_HandleApiCall(v8::internal::(anonymous namespace)::BuiltinArguments<(v8::internal::BuiltinExtraArguments)1>) ()
#5  0x00007f36b0fe01aa in ?? ()
#6  0x00007f36b0fe0141 in ?? ()
#7  0x00007fff5f9258a0 in ?? ()
#8  0x00007fff5f925908 in ?? ()
#9  0x00007f36b1022819 in ?? ()
#10 0x00007f36d6b08dc1 in ?? ()
#11 0x00007f36b0f334c9 in ?? ()
#12 0x00007f36b0f333a9 in ?? ()
#13 0x00007f36b0f2f0d9 in ?? ()
#14 0x00007f36b0f33291 in ?? ()
#15 0x00007f36b0ee0d39 in ?? ()