有一个十分让人不愉快的问题，最近程序运行经常卡在日志输出的地方。日志输出用了ostream流。最开始怀疑是 libc库和pthread库冲突的问题，显示加上了libc，但是还是没解决问题。
比如ostream< #0 0x00007f68239a5650 in **__write_nocancel ()** from /lib64/libc.so.6
#1 0x00007f682393bd53 in _IO_new_file_write () from /lib64/libc.so.6
#2 0x00007f682393d305 in _IO_new_do_write () from /lib64/libc.so.6
#3 0x00007f682393b9cd in _IO_new_file_xsputn () from /lib64/libc.so.6
#4 0x00007f6823931ccd in fwrite () from /lib64/libc.so.6
#5 0x00007f6823f73935 in std::basic_ostream >& std::__ostream_insert >(std::basic_ostream >&, char const*, long) () from /usr/lib64/libstdc++.so.6
#6 0x00007f682693a0a3 in es::DateLayout::format (this=0x1b1e6c0, output=..., msg=...) at /data/eshorebill/es/src/util/log/DateLayout.cpp:75
#7 0x00007f682692e22d in es::WriterAppender::doAppend (this=0x1b82960, msg=...) at /data/eshorebill/es/src/util/log/WriterAppender.cpp:33
#8 0x00007f682692caf4 in es::Appender::append (this=0x1b82960, msg=...) at /data/eshorebill/es/src/util/log/Appender.cpp:101