rsync with '-v' option hangups while syncing two directories in one host

Issue

• rsync with -v option hangups while two directories in one host

• All rsync process wait something with select system call. No read or write is issued:

  $ strace -p <PID of rsync>
  13737 12:59:43.621400 select(5, [], [4<UNIX:[2870095->2870094]>], [], {tv_sec=26, tv_usec=127746}) = 0 (Timeout) <26.153934>
  13737 13:00:09.775485 select(5, [], [4<UNIX:[2870095->2870094]>], [], {tv_sec=60, tv_usec=0}) = 0 (Timeout) <60.049580>
  13737 13:01:09.825148 select(5, [], [4<UNIX:[2870095->2870094]>], [], {tv_sec=60, tv_usec=0}) = 0 (Timeout) <60.001918>
  13737 13:02:09.827162 select(5, [], [4<UNIX:[2870095->2870094]>], [], {tv_sec=60, tv_usec=0}) = 0 (Timeout) <60.060038>
  13737 13:03:09.887292 select(5, [], [4<UNIX:[2870095->2870094]>], [], {tv_sec=60, tv_usec=0}) = 0 (Timeout) <60.060040>
  13737 13:04:09.947408 select(5, [], [4<UNIX:[2870095->2870094]>], [], {tv_sec=60, tv_usec=0}) = 0 (Timeout) <60.007637>
  13737 13:05:09.955126 select(5, [], [4<UNIX:[2870095->2870094]>], [], {tv_sec=60, tv_usec=0}) = 0 (Timeout) <60.060034>