Linux 对话在中断的会话中消耗 100% CPU
Linux dialog consuming 100% CPU in the broken session
当我通过 ssh（来自 windows 的 PuTTY）使用 /usr/bin/dialog 时，例如：
dialog --ok-label Select --cancel-label Cancel --stdout --backtitle BACKTITLE --menu TITLE 0 50 0 '1' 'alfa' '2' 'beta'
当显示对话框时，我通过 Alt-F4（或鼠标单击 X）关闭我的 putty 对话框进程没有退出但存在并获得 100% CPU:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
9928 user 20 0 113m 2308 1092 R 100.0 0.0 0:30.99 dialog
下面是我的 gdb 会话：
$ gdb -p 9928
GNU gdb (GDB) Red Hat Enterprise Linux (7.2-56.el6)
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Attaching to process 9928
Reading symbols from /usr/bin/dialog...(no debugging symbols found)...done.
Reading symbols from /usr/lib64/libdialog.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib64/libdialog.so.6
Reading symbols from /lib64/libncursesw.so.5...(no debugging symbols found)...done.
Loaded symbols for /lib64/libncursesw.so.5
Reading symbols from /lib64/libm.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib64/libm.so.6
Reading symbols from /lib64/libc.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib64/libc.so.6
Reading symbols from /lib64/libtinfo.so.5...(no debugging symbols found)...done.
Loaded symbols for /lib64/libtinfo.so.5
Reading symbols from /lib64/libdl.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib64/libdl.so.2
Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
Reading symbols from /usr/lib64/gconv/ISO8859-2.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib64/gconv/ISO8859-2.so
0x00007f902081e315 in fcntl () from /lib64/libc.so.6
Missing separate debuginfos, use: debuginfo-install dialog-1.1-9.20080819.1.el6.x86_64
(gdb) bt
#0 0x00007f902081e315 in fcntl () from /lib64/libc.so.6
#1 0x00007f9020fa3b5d in ?? () from /usr/lib64/libdialog.so.6
#2 0x00007f9020fa4230 in dlg_getc () from /usr/lib64/libdialog.so.6
#3 0x00007f9020fa15a3 in ?? () from /usr/lib64/libdialog.so.6
#4 0x00007f9020fa0668 in dlg_menu () from /usr/lib64/libdialog.so.6
#5 0x00007f9020fa131c in dialog_menu () from /usr/lib64/libdialog.so.6
#6 0x0000000000403916 in ?? ()
#7 0x000000000040415c in ?? ()
#8 0x00007f9020761cdd in __libc_start_main () from /lib64/libc.so.6
(gdb) continue
Continuing.
^C
Program received signal SIGINT, Interrupt.
0x00007f902081de00 in __read_nocancel () from /lib64/libc.so.6
(gdb) bt
#0 0x00007f902081de00 in __read_nocancel () from /lib64/libc.so.6
#1 0x00007f9020d6a277 in _nc_wgetch () from /lib64/libncursesw.so.5
#2 0x00007f9020d7f430 in wget_wch () from /lib64/libncursesw.so.5
#3 0x00007f9020fa401f in dlg_getc () from /usr/lib64/libdialog.so.6
#4 0x00007f9020fa15a3 in ?? () from /usr/lib64/libdialog.so.6
#5 0x00007f9020fa0668 in dlg_menu () from /usr/lib64/libdialog.so.6
#6 0x00007f9020fa131c in dialog_menu () from /usr/lib64/libdialog.so.6
#7 0x0000000000403916 in ?? ()
#8 0x000000000040415c in ?? ()
#9 0x00007f9020761cdd in __libc_start_main () from /lib64/libc.so.6
有什么想法吗？现在我在 cron 中有任务可以找到旧的对话框并杀死它们。
编译最新的 dialog 解决了我的问题。
我有 1.1-20080819 对话框版本，而现在我有 1.2-20140911 问题已解决。
@ThomasDickey 感谢您的建议。
给定版本1.1-20080819 is old. For instance a related problem was fixed in 2009/02/22:
modify dlg_result_key() to map curses ERR to dialog's error exit
(adapted from patch by Domagoj Pensa).
这又是对 2007/07/04 中所做更改的改进：
add a check when ERR returned from wgetch() to ensure that the
input/output streams are still valid. If that happens, force
ESC to be returned, quitting dialog (report by Reiner Huober).
目前，当前版本是1.2-20150225。
当我通过 ssh（来自 windows 的 PuTTY）使用 /usr/bin/dialog 时，例如：
dialog --ok-label Select --cancel-label Cancel --stdout --backtitle BACKTITLE --menu TITLE 0 50 0 '1' 'alfa' '2' 'beta'
当显示对话框时，我通过 Alt-F4（或鼠标单击 X）关闭我的 putty 对话框进程没有退出但存在并获得 100% CPU:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
9928 user 20 0 113m 2308 1092 R 100.0 0.0 0:30.99 dialog
下面是我的 gdb 会话：
$ gdb -p 9928
GNU gdb (GDB) Red Hat Enterprise Linux (7.2-56.el6)
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Attaching to process 9928
Reading symbols from /usr/bin/dialog...(no debugging symbols found)...done.
Reading symbols from /usr/lib64/libdialog.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib64/libdialog.so.6
Reading symbols from /lib64/libncursesw.so.5...(no debugging symbols found)...done.
Loaded symbols for /lib64/libncursesw.so.5
Reading symbols from /lib64/libm.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib64/libm.so.6
Reading symbols from /lib64/libc.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib64/libc.so.6
Reading symbols from /lib64/libtinfo.so.5...(no debugging symbols found)...done.
Loaded symbols for /lib64/libtinfo.so.5
Reading symbols from /lib64/libdl.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib64/libdl.so.2
Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
Reading symbols from /usr/lib64/gconv/ISO8859-2.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib64/gconv/ISO8859-2.so
0x00007f902081e315 in fcntl () from /lib64/libc.so.6
Missing separate debuginfos, use: debuginfo-install dialog-1.1-9.20080819.1.el6.x86_64
(gdb) bt
#0 0x00007f902081e315 in fcntl () from /lib64/libc.so.6
#1 0x00007f9020fa3b5d in ?? () from /usr/lib64/libdialog.so.6
#2 0x00007f9020fa4230 in dlg_getc () from /usr/lib64/libdialog.so.6
#3 0x00007f9020fa15a3 in ?? () from /usr/lib64/libdialog.so.6
#4 0x00007f9020fa0668 in dlg_menu () from /usr/lib64/libdialog.so.6
#5 0x00007f9020fa131c in dialog_menu () from /usr/lib64/libdialog.so.6
#6 0x0000000000403916 in ?? ()
#7 0x000000000040415c in ?? ()
#8 0x00007f9020761cdd in __libc_start_main () from /lib64/libc.so.6
(gdb) continue
Continuing.
^C
Program received signal SIGINT, Interrupt.
0x00007f902081de00 in __read_nocancel () from /lib64/libc.so.6
(gdb) bt
#0 0x00007f902081de00 in __read_nocancel () from /lib64/libc.so.6
#1 0x00007f9020d6a277 in _nc_wgetch () from /lib64/libncursesw.so.5
#2 0x00007f9020d7f430 in wget_wch () from /lib64/libncursesw.so.5
#3 0x00007f9020fa401f in dlg_getc () from /usr/lib64/libdialog.so.6
#4 0x00007f9020fa15a3 in ?? () from /usr/lib64/libdialog.so.6
#5 0x00007f9020fa0668 in dlg_menu () from /usr/lib64/libdialog.so.6
#6 0x00007f9020fa131c in dialog_menu () from /usr/lib64/libdialog.so.6
#7 0x0000000000403916 in ?? ()
#8 0x000000000040415c in ?? ()
#9 0x00007f9020761cdd in __libc_start_main () from /lib64/libc.so.6
有什么想法吗？现在我在 cron 中有任务可以找到旧的对话框并杀死它们。
编译最新的 dialog 解决了我的问题。
我有 1.1-20080819 对话框版本，而现在我有 1.2-20140911 问题已解决。
@ThomasDickey 感谢您的建议。
给定版本1.1-20080819 is old. For instance a related problem was fixed in 2009/02/22:
modify dlg_result_key() to map curses ERR to dialog's error exit (adapted from patch by Domagoj Pensa).
这又是对 2007/07/04 中所做更改的改进：
add a check when ERR returned from wgetch() to ensure that the input/output streams are still valid. If that happens, force ESC to be returned, quitting dialog (report by Reiner Huober).
目前，当前版本是1.2-20150225。